[Federal Register Volume 70, Number 111 (Friday, June 10, 2005)]
[Rules and Regulations]
[Pages 33998-34042]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-11480]



[[Page 33997]]

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Part III





Department of Health and Human Services





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Food and Drug Administration



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21 CFR Part 1020



Electronic Products; Performance Standard for Diagnostic X-Ray Systems 
and Their Major Components; Final Rule

  Federal Register / Vol. 70, No. 111 / Friday, June 10, 2005 / Rules 
and Regulations  

[[Page 33998]]


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DEPARTMENT OF HEALTH AND HUMAN SERVICES

Food and Drug Administration

21 CFR Part 1020

[Docket No. 2001N-0275]
RIN 0910-AC34


Electronic Products; Performance Standard for Diagnostic X-Ray 
Systems and Their Major Components

AGENCY: Food and Drug Administration, HHS.

ACTION: Final rule.

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SUMMARY: The Food and Drug Administration (FDA) is issuing a final rule 
to amend the Federal performance standard for diagnostic x-ray systems 
and their major components (the performance standard). The agency is 
taking this action to update the performance standard to account for 
changes in technology and use of radiographic and fluoroscopic x-ray 
systems and to fully utilize the International System of Units to 
describe radiation-related quantities and their units when used in the 
performance standard. For clarity and ease of understanding, FDA is 
republishing the complete contents, as amended, of three sections of 
the performance standard regulations and is amending a fourth section 
without republishing it in its entirety. This action is being taken 
under the Federal Food, Drug, and Cosmetic Act (the act), as amended by 
the Safe Medical Devices Act of 1990 (SMDA).

DATES: This rule is effective June 10, 2006.

FOR FURTHER INFORMATION CONTACT: Thomas B. Shope, Center for Devices 
and Radiological Health (HFZ-140), Food and Drug Administration, 9200 
Corporate Blvd., Rockville, MD 20850, 301-443-3314, ext. 132.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Background
II. Highlights of the Final Rule
III. Summary and Analysis of Comments and FDA's Responses
    A. General Comments
    B. Comments on Proposed Changes to Sec.  1020.30
    1. Definitions (Sec.  1020.30(b))
    2. Information to Be Provided to Users (Sec.  1020.30(h))
    3. Beam Quality--Increase in Minimum Half-Value Layer (Sec.  
1020.30(m))
    4. Aluminum Equivalent of Material Between Patient and Image 
Receptor (Sec.  1020.30(n))
    5. Modification of Certified Diagnostic X-Ray Components and 
Systems (Sec.  1020.30(q))
    C. Comments on Proposed Changes to Sec.  1020.31--Radiographic 
Equipment
    1. Field Limitation and Post Exposure Adjustment of Digital Image 
Size
    2. Policy Regarding Disabled Positive Beam Limitation Systems
    D. Comments on Proposed Changes to Sec.  1020.32--Fluoroscopic 
Equipment
    1. Testing for Attenuation By the Primary Protective Barrier
    2. Field Limitation for Fluoroscopic Systems
    3. Air Kerma Rates
    4. Minimum Source-Skin Distance
    5. Display of Cumulative Irradiation Time
    6. Audible Signal of Irradiation Time
    7. Last-Image-Hold (LIH) Feature
    8. Display of Values of Air Kerma Rate and Cumulative Air Kerma
IV. Additional Revisions of Applicability Statements and Other 
Corrections
V. Environmental Impact
VI. Paperwork Reduction Act of 1995
    A. Summary
    B. Estimate of Burden
VII. Analysis of Impacts
    A. Introduction
    B. Objective of the Rule
    C. Risk Assessment
    D. Constraints on the Impact Analysis
    E. Baseline Conditions
    F. The Amendments
    G. Benefits of the Amendments
    H. Estimation of Benefits
    I. Costs of Implementing the Regulation
    1. Costs Associated With Requirements Affecting Equipment Design
    2. Costs Associated With Additional Information for Users
    3. Costs Associated With Clarifications and Adaptations to New 
Technologies
    4. FDA Costs Associated With Compliance Activities
    5. Total Costs of the Regulation
    J. Cost-Effectiveness of the Regulation
    K. Small Business Impacts
    1. Description of Impact
    2. Analysis of Alternatives
    3. Ensuring Small Entity Participation in Rulemaking
    L. Reporting Requirements and Duplicate Rules
    M. Conclusion of the Analysis of Impacts
VIII. Federalism
IX. References

I. Background

    The SMDA (Public Law 101-629) transferred the provisions of the 
Radiation Control for Health and Safety Act of 1968 (RCHSA) (Public Law 
90-602) from title III of the Public Health Service Act (PHS Act) (42 
U.S.C. 201 et seq.) to chapter V of the act (21 U.S.C. 301 et seq.). 
Under the act, FDA administers an electronic product radiation control 
program to protect the public health and safety. As part of that 
program, FDA has authority to issue regulations prescribing radiation 
safety performance standards for electronic products, including 
diagnostic x-ray systems (sections 532 and 534 of the act (21 U.S.C. 
360ii(a) and 360kk)).
    The purpose of the performance standard for diagnostic x-ray 
systems is to improve the public health by reducing exposure to and the 
detriment associated with unnecessary ionizing radiation while assuring 
the clinical utility of the images produced.
    In order for mandatory performance standards to continue to provide 
the intended public health protection, the standards must be modified 
when appropriate to reflect the changes in technology and product 
usage. When the performance standard was originally developed, the only 
means of producing a fluoroscopic image was either a screen of 
fluorescent material or an x-ray image intensifier tube. Therefore, the 
standard was written with these two types of image receptors in mind. A 
number of technological developments have been implemented for 
radiographic and fluoroscopic x-ray systems, such as solid-state x-ray 
imaging (SSXI) and new modes of image recording (e.g., digital 
recording to computer memory or other media). These developments have 
made the application of the current standard to systems incorporating 
these new technologies cumbersome and awkward. FDA is therefore 
amending the performance standard for diagnostic x-ray systems and 
their major components in Sec. Sec.  1020.30, 1020.31, and 1020.32 (21 
CFR 1020.30, 1020.31, and 1020.32) to address the recent changes in 
technology. In addition, we are amending Sec.  1030.33(h) (21 CFR 
1030.33(h)) to reflect the change in the quantity used to describe 
radiation.
    These amendments will require that newly-manufactured x-ray systems 
include additional features that physicians may use to minimize x-ray 
exposures to patients. Advances in technology have made several of 
these new features feasible at minimal additional cost.
    In the Federal Register of August 15, 1972 (37 FR 16461), FDA 
issued a final rule for the performance standard, which became 
effective on August 1, 1974. Since then, FDA has made several 
amendments to the performance

[[Page 33999]]

standard to incorporate new technology, to clarify misinterpreted 
provisions, or to incorporate additional requirements necessary to 
provide for adequate radiation safety of diagnostic x-ray systems. 
(See, e.g., amendments published on October 7, 1974 (39 FR 36008); 
February 25, 1977 (42 FR 10983); September 2, 1977 (42 FR 44230); 
November 8, 1977 (42 FR 58167); May 22, 1979 (44 FR 29653); August 24, 
1979 (44 FR 49667); November 30, 1979 (44 FR 68822); April 25, 1980 (45 
FR 27927); August 31, 1984 (49 FR 34698); May 3, 1993 (58 FR 26386); 
May 19, 1994 (59 FR 26402); and July 2, 1999 (64 FR 35924)).
    In the Federal Register of December 11, 1997 (62 FR 65235), FDA 
issued an advance notice of proposed rulemaking (ANPRM) requesting 
comments on the proposed conceptual changes to the performance 
standard. The agency received 12 comments from State and local 
radiation control agencies, manufacturers, and a manufacturer 
organization. FDA considered these comments in developing the proposed 
amendments. In addition, the concepts embodied in the amendments were 
discussed on April 8, 1997, during a public meeting of the Technical 
Electronic Product Radiation Safety Standards Committee (TEPRSSC). 
TEPRSSC is a statutory advisory committee that FDA is required to 
consult before the agency may prescribe any electronic product 
performance standard under the act (21 U.S.C. 360kk(f)(1)(A)). The 
proposed amendments themselves were discussed in detail with the 
TEPRSSC during a public meeting held on September 23 and 24, 1998. At 
that meeting, TEPRSSC approved the content of the proposed amendments 
and concurred with their publication for public comment.
    FDA proposed the amendments for public comment in the Federal 
Register of December 10, 2002 (67 FR 76056). Interested persons were 
given until April 9, 2003, to comment on the proposal. FDA received 
comments from 12 organizations and individuals in response to the 
proposed amendments. These comments were generally supportive of the 
proposed changes to the performance standard, although some expressed 
concern about specific aspects of some of the proposed amendments.

II. Highlights of the Final Rule

    In this final rule, FDA is making a number of changes to the 
performance standard for diagnostic x-ray systems and their components, 
including the following:
     In Sec.  1020.30 of the performance standard, the final 
rule makes the following changes:
    Adds a number of new definitions to address new technologies and to 
further clarify the regulations. One notable amendment to the 
definitions is the addition of the terms air kerma and kerma to reflect 
a change in the quantity used to describe radiation emissions from 
diagnostic x-ray systems (Sec.  1020.30(b));
    Requires manufacturers to provide users (e.g., physicians) with 
certain information regarding the new features of fluoroscopic systems 
in order to better protect their patients from unnecessary x-radiation 
exposure (Sec.  1020.30(h));
    Requires additional warning label language designed to alert users 
and facility administrators to the need to properly maintain and 
calibrate their diagnostic x-ray systems (Sec.  1020.30(j)); and
    Modifies existing beam quality requirements by increasing the 
required minimum half-value layer (HVL) values for radiographic and 
fluoroscopic equipment. This increase in HVL values will bring FDA 
requirements into agreement with the performance already provided by 
systems that are compliant with corresponding international standards. 
Therefore, manufacturers currently complying with the international 
standards should not be impacted by this change (Sec.  1020.30(m)).
     In Sec.  1020.31 of the performance standard, which 
addresses radiographic x-ray equipment, the following changes are being 
made:
    A number of minor, technical corrections to sections applicable to 
mammographic x-ray systems that were made necessary by an oversight 
that occurred when this performance standard was amended in July 1999 
(Sec.  1020.31(f)(3) and (m)).
     The provisions in Sec.  1020.32 pertain to fluoroscopic 
equipment. Key changes being made to this section of the performance 
standard include the following:
    Amending the x-ray field limitation and alignment requirements to 
promote the addition of features designed to reduce the amount of 
radiation falling outside the visible area of the image receptor, 
thereby preventing unnecessary patient exposure (Sec.  1020.32(b));
    Amending the requirement concerning maximum limits on entrance air 
kerma rates (AKR) in order to clarify the circumstances under which the 
maximum limits would apply (Sec.  1020.32(d) and (e));
    Establishing a minimum source-skin distance requirement for certain 
small ``C-arm'' type fluoroscopic systems. FDA traditionally has 
granted variances from minimum source-skin distance requirements for 
small, portable C-arm systems when such systems were intended only for 
the limited use of imaging extremities. The amendment establishes the 
conditions under which variances have been granted as part of the 
standard and removes the need for manufacturers to continue to request 
variances of this type and makes explicit the requirements for these 
systems (Sec.  1020.32(g));
    Requiring the incorporation of a feature that will continuously 
display the last fluoroscopic image taken prior to termination of 
exposure (last-image-hold feature). This permits the user to 
conveniently view fluoroscopic images without continuously irradiating 
the patient (Sec.  1020.32(j)); and
    Requiring the incorporation of a feature that will display critical 
information to the fluoroscopist regarding patient irradiation, 
including the duration, rate (AKR), and amount (cumulative air kerma) 
of exposure (Sec.  1020.32(k));
     Section 1020.33 addresses computed tomography (CT) 
equipment. With regard to CT systems, the final rule makes the 
following changes:
    Amends the requirements pertaining to beam-on and shutter status 
indicators to reflect the change in quantity used to describe x-
radiation from exposure to air kerma. This modification does not alter 
the level of radiation protection provided by the existing standard 
(Sec.  1020.33(h)).

III. Summary and Analysis of Comments and FDA's Responses

A. General Comments

    (Comment 1) FDA received 12 comments on the proposed amendments to 
the performance standard, many of which addressed multiple issues. In 
general tone and content all 12 individuals or organizations that 
commented supported the need for amendments and the approach proposed 
by FDA. A number of the comments provided suggestions or critiques 
regarding specific aspects of the proposed changes or suggested 
additional changes or additions for FDA consideration that were not 
part of the FDA proposal. The specific comments and FDA's responses 
will be discussed in the following paragraphs for each section of the 
performance standard.
    Seven of the comments provided general comments that did not 
address specific proposed changes. Some of

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them addressed the impact analysis or the estimate of the potential 
benefits that would likely result from the amendments. All seven 
comments were generally supportive of the changes proposed by FDA. Two 
comments suggested that the benefits of the proposed changes would be 
greater than estimated by FDA. One comment, from a State agency, 
suggested that the patient dose reductions would be greater than 
estimated by FDA, based on the State agency's experience with programs 
that have improved the information provided to facilities regarding 
patient radiation doses. Another comment suggested that the benefit of 
any dose reduction resulting from the amendments would greatly exceed 
FDA's estimates and criticized FDA for suggesting that the risk from x-
ray radiation is much less than the comment believes it to be. Two of 
the comments complimented FDA on its analysis of the potential impact 
of the regulation.
    (Response) We acknowledge and appreciate the supportive comments. 
This rule includes important modifications to the Federal performance 
standard for diagnostic x-ray systems to address recent changes in the 
technology and usage of radiographic and fluoroscopic x-ray systems. 
These modifications will help ensure that the performance standard will 
continue to protect and improve the public health by reducing exposure 
to unnecessary ionizing radiation while assuring the continued clinical 
utility of images produced where these new technologies are in use.
    (Comment 2) Two comments questioned the need to apply several of 
the requirements to all fluoroscopic x-ray systems, noting that the 
benefit of the requirements such as for display of dose information and 
a last-image-hold feature would largely result from fluoroscopic 
equipment used for interventional procedures. At least five other 
comments explicitly supported application of the requirements to all 
fluoroscopic systems.
    (Response) FDA notes that performance requirements must be tied to 
equipment characteristics and not to the potential manner in which the 
equipment may be used. Because interventional procedures may be 
performed using many types of fluoroscopic equipment, and because the 
added costs of the requirements are not expected to be overly 
burdensome, FDA has determined that the requirements should apply to 
all fluoroscopic equipment as proposed.
    (Comment 3) Two comments supported the change in the quantity 
proposed for the description of radiation in the standard from exposure 
to air kerma. One of these comments was fairly general, while the other 
expressed specific support for the approach taken in the proposal that 
will maintain all of the various limits on radiation contained in 
different requirements of the standard at the same effective level as 
in the limits in the current standard where they were expressed using 
the quantity roentgen.
    (Response) FDA believes that the radiation limits contained in the 
existing requirements remain appropriate. Although the change from 
exposure to air kerma will result in different numerical values that 
may no longer be integer numbers or multiples of 5 or 10 as was 
previously the case, the level of radiation protection will effectively 
be the same.
    (Comment 4) FDA received comments in response to questions posed by 
the agency in the preamble of the proposed rule. FDA invited comments 
on several questions regarding approaches that could be taken to assure 
the radiation safety of fluoroscopic systems through performance 
requirements. These questions, which were not associated with specific 
proposed amendments, were intended to gather information that might 
guide FDA in considering any future modifications to the performance 
standard. Among the questions FDA presented for comment was whether 
there are any clinical situations that could require entrance AKRs 
greater than those currently permitted. FDA also invited comment on 
whether limits should be established for the entrance AKR at the 
entrance surface of the fluoroscopic image receptor and, if so, how 
these limits might be determined and established.
    FDA received three comments in response to the questions about 
entrance air kerma rates. Two comments recommended that limits should 
not be established for the entrance air kerma rate at the entrance 
surface of the fluoroscopic image receptor. A third comment suggested 
that a mode of operation that would permit momentary imaging with 
entrance air kerma rates exceeding current limits should be considered 
if limits were to be established for the entrance air kerma rate at the 
entrance to the fluoroscopic image receptor. This comment also noted 
that any consideration of limits should involve the corresponding 
fluoroscopic image quality, and suggested that this is an area for 
further consideration by FDA in collaboration with interested parties. 
However, these comments did not make specific suggestions for 
requirements or provide data or evidence regarding such requirements.
    (Response) FDA appreciates these suggestions. Although FDA has 
decided not to implement them at this time, FDA will involve interested 
parties in discussions about such requirements if modifications such as 
these are undertaken in the future.
    (Comment 5) Two comments supported the need to modify the 
performance standard to address newly-evolving technologies. Although 
both comments agreed with FDA's proposed approach, they suggested that 
any future efforts to further address new technology with additional 
performance requirements, beyond the current proposed changes, would 
benefit from additional consultations between FDA and interested or 
affected parties. One of these comments suggested that consideration of 
further requirements to address additional characteristics of digital 
detectors or solid state x-ray imaging devices would benefit from 
interactive consultations with professional and scientific 
organizations. The other comment suggested that these areas could be 
addressed through the International Electrotechnical Commission's (IEC) 
standards development process.
    (Response) FDA agrees with these suggestions and will encourage and 
facilitate such discussions should the future development of additional 
amendments be undertaken.

B. Comments on Proposed Changes to Sec.  1020.30

1. Definitions (Sec.  1020.30(b))
    As discussed in the preamble to the proposed rule, FDA proposed the 
inclusion of a number of new definitions in Sec.  1020.30(b) to address 
new technologies and to further clarify the regulations. In addition to 
the changes to definitions proposed by FDA, a number of comments 
suggested modifications of additional, existing definitions or noted 
that new definitions were needed for clarity.
    (Comment 6) One comment suggested that the definitions in the 
standard be harmonized to the extent possible with those used by the 
IEC.
    (Response) FDA declines to make this change. The definitions in the 
U.S. standard were developed and finalized before the development of 
the IEC standards for x-ray equipment. Complete adoption of the IEC 
definitions would require FDA to overhaul the entire U.S. standard to 
bring it in line with the different structure and approach used in the 
IEC standards. In addition, the U.S. standard

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reflects differences in common usage. For example, the IEC standard 
uses the term ``radioscopy'' instead of the term ``fluoroscopy'' as 
commonly used in the United States. For these reasons, FDA does not 
believe that such wholesale revisions are warranted at this time.
    (Comment 7) FDA received a comment concerning the definition of 
attenuation block that noted that the current size specified is not 
large enough to accommodate the large x-ray field sizes used in 
conjunction with some current fluoroscopic image receptors that are 
significantly larger than earlier image receptors.
    (Response) In response to this comment, FDA has modified the 
definition to indicate that an attenuation block with dimensions larger 
than currently specified is allowed. The new definition reads:
    Attenuation block means a block or stack of type 1100 aluminum 
alloy or aluminum alloy having equivalent attenuation with 
dimensions 20 centimeters or larger by 20 centimeters or larger by 
3.8 centimeters. When used, the attenuation block shall be large 
enough to intercept the entire x-ray beam.
    (Comment 8) One comment suggested the need for clarification of 
what the term C-arm fluoroscope means as used in the standard.
    (Response) FDA agrees that clarification would be useful and has 
included a new definition for this term in the final rule. The new 
definition reads:
    C-arm fluoroscope means a fluoroscopic x-ray system in which the 
image receptor and x-ray tube housing assembly are connected or 
coordinated to maintain a spatial relationship. Such a system allows 
a change in the direction of the beam axis with respect to the 
patient without moving the patient.
 Note that this definition will include some systems in which the x-ray 
tube and the fluoroscopic imaging assembly are not connected by a C-
shaped mechanical connection. The distinguishing feature of a C-arm 
fluoroscope is the capability to change the orientation of the x-ray 
beam.
    (Comment 9) In the preamble to the proposed rule, FDA noted that 
the word ``exposure'' is used in the standard with two different 
meanings. One comment suggested adding the second meaning of exposure 
to the definition for clarity.
    (Response) FDA agrees with this comment. Accordingly, the 
definition of exposure is revised to read:
    Exposure (X) means the quotient of dQ by dm, where dQ is the 
absolute value of the total charge of the ions of one sign produced 
in air when all the electrons and positrons liberated or created by 
photons in air of mass dm are completely stopped in air; thus X=dQ/
dm, in units of C/kg. Exposure is also used with a second meaning to 
refer to the process or condition during which the x-ray tube 
produces x-ray radiation.
    (Comment 10) One comment suggested that the definition of image 
intensifier be modified to add a comparison to a simple fluorescent 
screen.
    (Response) FDA has concluded that such a change is not warranted. 
However, this comment prompted further review of the definition of 
fluoroscopy. As a result of this further review, FDA believes the 
proposed definition of fluoroscopy should be modified to remove the 
description that the images are presented instantaneously to the user. 
The word ``instantaneously'' is unnecessarily restrictive and 
ambiguous. It could result in confusion in certain situations such as 
when some short but finite time is required to process digital images 
before displaying them to the user. A further clarification has been 
added to note that, whereas ``fluoroscopy'' conforms to common usage in 
the United States, it has the same meaning as ``radioscopy'' in the IEC 
standards. Therefore, the definition of fluoroscopy is changed to read:
    Fluoroscopy means a technique for generating a sequence of x-ray 
images and presenting them simultaneously and continuously as 
visible images. This term has the same meaning as the term 
`radioscopy' in the standards of the International Electrotechnical 
Commission.
    (Comment 11) One comment suggested that FDA clarify the meaning of 
the term ``C-arm gantry'' as used in the proposed definition of 
isocenter.
    (Response) FDA agrees that clarification of this term would be 
useful and has revised the proposed definition of isocenter to read:
    Isocenter means the center of the smallest sphere through which 
the beam axis passes when the equipment moves through a full range 
of rotations about its common center.
    (Comment 12) Several comments suggested that FDA clarify the 
proposed definition of mode of operation.
    (Response) FDA agrees that clarification is needed and has modified 
this definition. Mode of operation is defined for the purpose of 
assuring that adequate instructions are provided to the user on how to 
operate the fluoroscopic system. A mode of operation is intended to 
describe the state of system operation in which a set of several 
technique factors or other control settings are selected to perform a 
specific type of imaging task or procedure. Within a specific mode of 
operation, a variety of anatomical or examination-specific technique 
selections may be provided, either pre-programmed, under automatic 
control, or manually-selected.
    (Comment 13) One comment suggested that the proposed definition of 
mode of operation would allow wide variations in AKR within a given 
mode of operation and that such variations would cause conflict with 
several items in Sec.  1020.30(h). The comment suggested that FDA 
consider using the definition and information requirements of the IEC 
standard IEC 60601-2-43, ``Particular Requirements for the Safety of X-
Ray Equipment for Interventional Radiology'' (Ref. 1).
    (Response) FDA disagrees that the proposed definition will conflict 
with items of information required by Sec.  1020.30(h). It is true that 
specification of a mode of operation does not in itself determine the 
AKR produced by the mode, as variations of technique factors or other 
controls within a given mode of operation can produce wide variations 
in the amount of radiation emitted by the system. Such variation, 
however, does not conflict with Sec.  1020.30(h). Proposed Sec.  
1020.30(h)(5) would require a description of each mode of operation, 
and Sec.  1020.30(h)(6) would require information about the AKR and 
cumulative air kerma displays. These sections do not require dose data 
for each mode in the information to be provided to users under Sec.  
1020.30(h). The IEC standard IEC 60601-2-43 does require providing 
certain dose information regarding some of the operating modes for 
fluoroscopic systems intended for interventional uses, but this IEC 
requirement would not conflict with the proposed changes to the 
performance standard.
    FDA notes that the definition it is adopting for ``mode of 
operation'' differs from the definition used in paragraph 2.107 of the 
IEC standard IEC 60601-2-43. The IEC standard defines a mode of 
operation for interventional x-ray equipment as ``* * * the technical 
state defined by a configuration of several predetermined loading 
factors, technique factors or other settings for radioscopy or 
radiography, selectable simultaneously by the operation of a single 
control.'' FDA does not think it necessary to limit a mode of operation 
to system operation selected by operation of a single control. The 
definition in this final rule includes methods of system operation that 
have specific or unique features or intended purposes about which the 
user should be informed in detail. The term mode of operation in this 
rule addresses only the information that must be provided to the user 
under Sec.  1020.30(h)(5), which requires that users receive complete 
instructions regarding the operation and intended function of each mode 
of operation.

[[Page 34002]]

    FDA does not require information related to the reference AKR for 
modes of operation as does the IEC standard. FDA notes that the 
required display of AKR will directly inform users regarding actual 
entrance AKRs during use. FDA has determined that it is important that 
users receive complete descriptions in the user's manual of all the 
different modes of operation and their intended purposes or types of 
imaging procedures for which they are designed.
    The definition of mode of operation has therefore been modified to 
read:
    Mode of operation means, for fluoroscopic systems, a distinct 
method of fluoroscopy or radiography provided by the manufacturer 
and selected with a set of several technique factors or other 
control settings uniquely associated with the mode. The set of 
distinct technique factors and control settings for the mode may be 
selected by the operation of a single control. Examples of distinct 
modes of operation include normal fluoroscopy (analog or digital), 
high-level control fluoroscopy, cineradiography (analog or digital), 
digital subtraction angiography, electronic radiography using the 
fluoroscopic image receptor, and photospot recording. In a specific 
mode of operation, certain system variables affecting air kerma, 
AKR, or image quality, such as image magnification, x-ray field 
size, pulse rate, pulse duration, number of pulses, SID, or optical 
aperture, may be adjustable or may vary; their variation per se does 
not comprise a mode of operation different from the one that has 
been selected.
    (Comment 14) One comment suggested that FDA change the definition 
of a solid-state x-ray imaging device to make it less specific and 
therefore more likely to accommodate changes in technology.
    (Response) FDA agrees. The definition has been modified to read:
    Solid-state x-ray imaging device means an assembly, typically in 
a rectangular panel configuration, that intercepts x-ray photons and 
converts the photon energy into a modulated electronic signal 
representative of the x-ray image. The electronic signal is then 
used to create an image for display and/or storage.
    (Comment 15) One comment suggested that the existing definition of 
visible area needs clarification with respect to its use with solid-
state x-ray imaging devices. The comment suggested that the definition 
clarify that the visible area can include both active and inactive 
elements of the detector when inactive elements are within the outer 
borders of the overall area.
    (Response) FDA has determined that modification of this definition 
is not necessary. FDA notes that the ``area'' cited in this definition 
is the overall area defined by the external dimensions of the area over 
which photons are detected to form an image. It includes any inactive 
elements that might be located between active elements of the image 
receptor.
    (Comment 16) FDA also received comments suggesting changes to some 
of the existing definitions that were not proposed for modification in 
the proposed amendments, including the definitions for beam axis, 
cradle, pulsed mode, source-image receptor distance (SID), portable x-
ray equipment, and stationary x-ray equipment.
    (Response) FDA carefully reviewed the suggestions and has 
determined that no changes to these definitions are warranted at this 
time. However, as FDA reviewed the comments received regarding proposed 
changes to the definitions, it became apparent to the agency that 
several additional definitions would be useful to further clarify some 
of the terms used in the performance standard. Therefore, FDA has added 
new definitions for the terms air kerma rate, cumulative air kerma, and 
fluoroscopic irradiation time. These definitions are not intended to 
impose any new requirements.
    The new definitions read as follows:
     Air kerma rate (AKR) means the air kerma per unit time.
     Cumulative air kerma means the total air kerma accrued 
from the beginning of an examination or procedure and includes all 
contributions from fluoroscopic and radiographic irradiation.
     Fluoroscopic irradiation time means the cumulative 
duration during an examination or procedure of operator-applied 
continuous pressure to the device enabling x-ray tube activation in any 
fluoroscopic mode of operation.
2. Information to Be Provided to Users (Sec.  1020.30(h))
    (Comment 17) Three comments suggested an expansion of the scope of 
information required to be provided to users by manufacturers. These 
comments suggested that the manufacturer be required to provide: (1) A 
full set of system schematics to permit the user or a third party to 
troubleshoot electronic problems and perform repairs; (2) system-
specific hardware and software tools to permit a qualified individual 
to accomplish quality assurance tests without the need for service 
support; or (3) appropriate tools and instructions for their use, 
either as part of the system or as required accessories, to permit any 
``physics measurements'' needed to assure system performance.
    (Response) An expansion of existing information requirements was 
not contemplated in the proposed rule. Such requirements could have 
significant impact on manufacturers of diagnostic x-ray equipment and 
neither should be established without a full opportunity for affected 
parties to comment on specific proposals, nor should such requirements 
be established without a thorough assessment of the potential benefits 
and impacts of such requirements. Therefore, FDA is not incorporating 
the suggested requirements into the amendments at this time.
    (Comment 18) One comment supported the proposed requirement that 
manufacturers provide additional, detailed information regarding the 
variety of fluoroscopic system modes of operation. This comment 
suggested that manufacturers be required to provide data on the 
entrance AKR for each mode of operation and further suggested that such 
a requirement could be less costly than the proposed requirement for a 
display of air kerma information on fluoroscopic systems. The comment 
suggested that users could infer approximate patient doses from such 
information with a degree of accuracy comparable to that of the 
displayed air kerma information.
    (Response) FDA considered the approach described in this comment 
when developing the proposal and determined that providing the user 
with information on patient doses through data on typical entrance air 
kerma rates for each mode of operation was not practical and would not 
have the benefits associated with a real-time display of AKR and 
cumulative air kerma information. In FDA's opinion, either the entrance 
AKR is highly variable within a given mode of operation or there are so 
many different modes of operation, which would require separate AKR 
data, as to make this approach ineffective in informing physicians 
about the doses delivered to a patient in a procedure. For systems with 
a number of operating modes, it would be difficult for the user to 
remember all of the various entrance AKRs. The real-time display 
provides this information on a continuous basis for every patient, 
independent of the specific mode selected. For example, interventional 
procedures, with their associated long exposure times, may be 
undertaken on a variety of types of fluoroscopic systems. It does not 
appear feasible to distinguish the type of system that should have the 
real-time display from those for which such a display would not be 
useful.
    The real-time displays are anticipated to have dose-reduction 
benefits even in noninterventional procedures. Providing users with 
immediate information related to patient doses is expected to have an 
impact on use of

[[Page 34003]]

the equipment. In addition, the uncertainty in estimating an individual 
patient's specific radiation dose from a reference AKR provided for a 
mode of operation is expected, typically, to be much greater than the 
uncertainty in the real-time values displayed. This increased 
uncertainty is due to the wide variation in AKR possible within a given 
mode of operation because of variations in technique factors or other 
control factors, patient size and attenuation, and the specific beam 
orientations of an individual procedure.
    (Comment 19) One comment suggested that the current wording of 
Sec.  1020.30(h)(1)(i) be modified to emphasize that the adequate 
instructions required by the section be suitably written for physician 
operators.
    (Response) FDA does not believe that modification of the current 
wording is needed. The requirement for adequate instructions embodies 
the concept of being adequate for the intended audience. Since 
diagnostic x-ray systems are prescription devices, there is a presumed 
level of knowledge regarding the use of x-ray equipment on the part of 
the users.
    (Comment 20) A comment questioned the preamble statement regarding 
unique features of equipment that require adequate instructions 
regarding radiological safety procedures and the precautions needed 
because of these features. FDA noted that any mode of operation that 
yields an entrance AKR greater than 88 mGy/min should be considered a 
unique mode, and sufficient information should be provided to enable 
the user to understand the patient dose implications of using that 
mode. The comment questioned whether an 88 mGy/min threshold should be 
applied to radiographic modes and further suggested that there be a 
requirement that any fluoroscopic mode capable of delivering more than 
88 mGy/min be explicitly listed as a mode of operation and that 
standardized information regarding entrance AKR be provided for each 
such mode.
    (Response) FDA disagrees with this comment. As noted in the 
preamble of the proposed rule, data regarding the doses from specific 
modes of operation are not being required in the information for users. 
Rather, the newly-required AKR and cumulative air kerma displays will 
be relied on to provide users real-time information on air kerma at the 
reference location which can be related to patient dose. Values of the 
AKR and cumulative air kerma displayed in real-time do not necessitate 
adjustments for particular imaging technique factors or patient size as 
would standardized tabulations of AKR information printed as user 
information for each mode.
    (Comment 21) The same comment also suggested that manufacturers be 
required to provide standardized AKR data for fluoroscopic modes of 
operation as required in IEC standard IEC 60601-2-43, including 
information regarding the AKR for each available frame rate possible 
during the normal mode of operation.
    (Response) FDA did not accept this suggestion, which is also 
addressed in the discussion in the previous paragraphs about the 
definition of mode of operation. FDA notes that proposed Sec.  
1020.32(k) is being revised as described in the following paragraphs to 
clarify the conditions under which the display of AKR is required. 
Proposed Sec.  1020.30(h)(5) has been revised to require that 
information be provided to users for all modes of operation that 
produce images using the fluoroscopic image receptor regarding the 
impact of the mode selected on the resulting technique factors. This 
includes any mode that produces radiographic images from the 
fluoroscopic image receptor.
    (Comment 22) One comment suggested several changes to the 
performance standard that were not included in the proposed rule. These 
suggestions were that in several sections of the performance standard, 
where specification of the maximum kilovolts peak (kVp) or a specified 
kVp is stated, there should be a specification of the characteristics 
of the kV waveform. In particular, the comment suggested that a 
waveform having a voltage ripple of less than or equal to 10 percent be 
required. One of these sections is 1020.30(h)(2)(i), which requires the 
specification of the peak tube potential at which the aluminum 
equivalent of the minimum filtration in the beam is determined. The 
other is the requirement in Sec.  1020.30(m) for the kVp at which the 
minimum HVL values are determined. The comment addresses the 
requirement that manufacturers provide information regarding the peak 
tube potential at which the aluminum equivalent of the beam filtration 
provided by the tube housing assembly or permanently in the beam is 
determined. The comment points out the fact that the determination of 
the aluminum equivalent is also dependent on the voltage waveform as 
well as the peak tube potential.
    (Response) FDA will further consider this comment and if it 
determines that such a modification to the standard is warranted, a 
proposal will be published for public comment. Without specification of 
the waveform, uncertainty can be introduced into the specification of 
the aluminum equivalence of the filtration because this determination 
depends on the voltage waveform and the resulting energy spectrum of 
the beam. FDA notes that the IEC standard IEC 60601-1-3 (Ref. 2) that 
establishes the minimum HVL requirements for diagnostic x-ray systems 
does not specify the voltage waveform as part of the test method for 
determining the aluminum equivalence. Rather, the requirement is 
specified as a function of the selected operating x-ray tube voltage 
over the normal range of use and is therefore dependent on the waveform 
of the specific x-ray generator being tested.
    When the method for determining HVL was initially established, 
there were fewer generator designs and voltage waveforms than there are 
currently. It is correct that a complete specification of equivalent 
filtration would require a specification of the voltage waveform with 
which it was determined, as well as peak tube potential. However, there 
are no tolerances or specifications given in the standard regarding the 
accuracy with which the filtration equivalent is to be specified. FDA 
notes that one might conclude that since no requirements exist in the 
standard for the accuracy of the statement regarding filtration 
equivalent, it does not need to be so precise as to require description 
of or limitation on the waveform used. Note that a similar requirement 
exists in 1020.30(h)(4)(ii) for beam-limiting devices.
    (Comment 23) One comment strongly supported the consolidation of 
instructions for use of the various modes of operation of fluoroscopic 
systems into a single section of the user's instructions. The comment 
further suggested that the instructions be required to include a 
description of all of the controls accessible to the operator at the 
normal working position.
    (Response) FDA does not believe that such a requirement is 
necessary, as FDA expects that any user's instructions will include a 
complete description of all controls, including any controls available 
at the operator's working position.
    (Comment 24) Three comments expressed concern regarding the 
requirement in proposed Sec.  1020.30(h)(5) that manufacturers describe 
specific clinical procedures or uses for which a specific mode of 
operation is designed or intended. The concern expressed was that the 
clinical use of the fluoroscopic system should not be limited by any 
statements required of the manufacturer

[[Page 34004]]

regarding the purposes of any mode of operation.
    (Response) FDA agrees that clinical use of the system should not be 
limited to the examples provided by the manufacturer. The manner of use 
and the decision to use a particular mode of operation are medical 
decisions. In addition, the requirements of the performance standard 
apply only to manufacturers and do not impose requirements on the users 
of such systems. The requirement at Sec.  1020.30(h)(5)(ii) has been 
modified to reflect that a manufacturer's descriptions of particular 
clinical procedures exemplifying the use of specific modes of operation 
do not limit when or how any mode may be used in actual clinical 
practice.
    In addition, FDA has revised Sec.  1020.30(h)(5)(i) to further 
elaborate the type of information required to be provided to users with 
respect to the description of modes of operation. FDA believes it is 
important for users to understand the manner in which a given mode of 
operation controls the system technique factors and that this 
information should be included in the description of the mode of 
operation.
    (Comment 25) An error in the proposed rule, which was detected by 
FDA following publication, was pointed out by one of the comments. 
Proposed Sec.  1020.30(h)(6)(i) would have required a statement by the 
manufacturer of the maximum deviations of the values of AKR and 
cumulative air kerma from their displayed values.
    (Response) This requirement should have been removed from the 
proposed rule as it was replaced by the requirement in proposed Sec.  
1020.32(k)(7) specifying the maximum deviation allowed. Proposed Sec.  
1020.30(h)(6)(i) has been removed and Sec.  1020.32(k)(7) has been 
revised to be Sec.  1020.32(k)(6). This revision of Sec.  1020.32(k) is 
described in section III.D.8 of this document.
    (Comment 26) One comment suggested that, in addition to requiring 
instructions and schedules for calibrating and maintaining any 
instrumentation required for measurement or evaluation of the AKR and 
cumulative air kerma, Sec.  1020.30(h)(6)(ii) should also require 
manufacturers to provide any hardware or software tools or accessories 
necessary to accomplish such calibration or maintenance.
    (Response) FDA is not adding such a requirement to the standard at 
this time, but will consider it along with the other suggestion 
regarding information or equipment features that should be included in 
the performance standard.
3. Beam Quality--Increase in Minimum Half-Value Layer (Sec.  
1020.30(m))
    (Comment 27) One comment objected to the revision of the 
requirements for minimum half-value of the x-ray beam in Sec.  
1020.30(m)(1) on the grounds that the new minimum requirements for all 
systems should not be based on what the comment considered to be state-
of-the-art equipment. The comment suggested a set of reduced minimum 
values.
    (Response) It appears that the comment misunderstood the basis for 
the FDA proposal and the intent of the increased HVL values. Currently, 
to comply with paragraph 29.201.5 of the IEC standard IEC 60601-1-3, 
all x-ray systems other than mammographic and some dental x-ray systems 
must contain total filtration material in the x-ray beam that provides 
a quality equivalent filtration (using IEC terminology) of not less 
than 2.5 millimeters of aluminum (mm Al). Thus, all currently 
manufactured x-ray systems should be manufactured in a manner that 
assures this amount of filtration in the beam if compliance with the 
IEC standard is claimed. The proposal to increase the HVL requirements 
in the FDA standard, which must be expressed as a performance standard 
rather than as a design standard for a given thickness of filtration, 
is intended to provide HVL values that correspond to those that result 
from the use of a filtration corresponding to the 2.5 mm Al required by 
the current IEC standard. Therefore, the changes proposed for HVL will 
simply bring FDA's requirements into agreement with the performance 
provided by systems complying with the IEC standards IEC 60601-1-3 and 
IEC 60601-2-43. Manufacturers currently complying with the IEC standard 
should experience no impact from this change as all of their production 
should already meet the requirement. Therefore, the change suggested by 
the comment is not necessary.
    FDA notes that several values in table 1 in proposed Sec.  
1020.30(m)(1) are being revised in order to fully agree with existing 
and proposed IEC standards that address the minimum HVL for diagnostic 
x-ray systems. The values of HVL in table 1 in proposed Sec.  
1020.30(m)(1) for several tube voltages in the column heading ``II--
Other X-Ray Systems''are being changed. The changes will have no 
significant impact on the radiation safety provided by the amendment.
    (Comment 28) In conjunction with the proposed revision of the 
requirements for the minimum HVL of the x-ray beam, one comment 
suggested a 60 kVp lower limit for intraoral dental x-ray systems. The 
comment suggested that systems with lower kVp capabilities are not dose 
efficient.
    (Response) FDA notes that a previous amendment to the performance 
standard in 1979 increased the beam quality requirements for x-ray 
systems manufactured after December 1, 1980. The increased beam quality 
required of these systems was intended to preclude systems from 
operating below 70 kVp, while complying with the beam quality 
requirements. FDA believes that the modified requirements that became 
effective in 1980 limited the ability of dental intraoral x-ray systems 
to operate at lower voltages. FDA is not aware of information 
indicating that there are significant numbers of newly-manufactured 
systems that operate with such low voltage capability. Should FDA 
become aware that the current requirements are not effective in 
limiting the beam quality of intraoral dental x-ray systems to 
appropriate values, future consideration will be given to proposing an 
appropriate amendment.
    (Comment 29) Two comments suggested that Sec.  1020.30(m)(2) 
contain a requirement that the system provide an indication to the user 
of the amount of additional filtration that is in the beam at any time 
during system use. The comments did not express a preference for the 
location for this display, indicating that it could be at the system 
control console or at the operator's location. A third comment 
supported the addition of Sec.  1020.30(m)(2), noting the impact of the 
requirement in reducing patient dose and maintaining image quality.
    (Response) FDA agrees that there should be a requirement for a 
display of the amount of additional filtration in use because it is 
important that the operator of the system be able to easily determine 
the added filtration that is currently in use during any procedure. An 
active display of this information will assist the operator. 
Manufacturers of systems that currently do not provide such a feature 
will be required to redesign to implement the capability to select and 
add filtration.
    Accordingly, FDA has modified proposed Sec.  1020.30(m)(2) to 
require an indication of the additional filtration in the beam. FDA has 
also clarified the requirement to state that the selection or insertion 
of the additional filtration can be either at the option of the user or 
automatically accomplished as part of the selected mode of operation. 
FDA notes that automatic selection and concurrent modification of the

[[Page 34005]]

technique factors to maintain image quality is the preferred method of 
operation. Efficient manual use of additional filtration requires that 
the user make appropriate technique changes to preserve optimum image 
quality.
    FDA notes that, through an oversight, no effective date was 
proposed for the new requirement in Sec.  1020.30(m)(2). This new 
requirement was intended to become effective, along with all of the 
other new requirements, 1 year after the date of publication of the 
amendments in the Federal Register. FDA has modified proposed Sec.  
1020.30(m)(2) to reflect the effective date.
4. Aluminum Equivalent of Material Between Patient and Image Receptor 
(Sec.  1020.30(n))
    (Comment 30) One comment noted that the values given in table 2 in 
Sec.  1020.30(n) need to be revised as a result of the revision of 
Sec.  1020.30(m)(1). According to the comment, if the values of the 
maximum aluminum equivalence given in table 2 are not revised to 
reflect the increased beam quality required by Sec.  1020.30(m)(1) for 
the test voltage of 100 kVp for determining compliance with Sec.  
1020.30(n), the current requirements of table 2 in Sec.  1020.30(n) 
would in effect require that items between the patient and the image 
receptor provide less attenuation than currently required.
    (Response) The comment is correct that FDA's proposal was not 
intended to reduce the limits on the maximum allowed aluminum 
equivalence of materials between the patient and the image receptor. 
The comment is also correct that the values in table 2 in Sec.  
1020.30(n) were based on the beam qualities associated with the current 
values in table 1 in Sec.  1020.30(m)(1), reflecting a beam quality of 
2.7 mm of aluminum HVL, and not the beam quality described in the 
proposed revision of Sec.  1020.30(n), which is an HVL of 3.6 mm Al at 
100 kVp. However, the comment's reference to the values in table 2 in 
Sec.  1020.30(n) as HVL values was incorrect, although that does not 
invalidate the concern raised by the comment. Therefore, FDA is 
revising the values in table 2 in Sec.  1020.30(n) for the maximum 
aluminum equivalent of materials between the patient and image receptor 
to reflect requirements that are met by current products that comply 
with the present standard. These revised limits are consistent with the 
maximum limits used in current IEC standard IEC 60601-1-3 (Ref. 2). 
This change continues the current requirement for maximum aluminum 
equivalence, but has no impact on current products and will not require 
changes in design.
5. Modification of Certified Diagnostic X-Ray Components and Systems 
(Sec.  1020.30(q))
    (Comment 31) Two comments suggested that a party other than the 
owner be required to certify the continued compliance of any certified 
system that is modified in accordance with Sec.  1020.30(q).
    (Response) The current requirement was not proposed for change and 
no change is considered necessary by FDA. As discussed in the preamble 
to the proposed rule, the requirement in Sec.  1020.30(q)(2) states 
that the owner of an x-ray system may modify the system, provided that 
the modification does not result in a failure of the system to comply 
with an applicable requirement of the performance standard. In 
accomplishing such a modification, the owner may employ a third party 
with the requisite skills and knowledge to accomplish the modification 
in a manner that does not result in noncompliance. As the responsible 
party, the owner should assure that any modifications are accomplished 
appropriately. This can be done through contractual arrangements with 
the party performing the modifications to assure compliance is 
maintained or through any other means that satisfies the owner that 
compliance has not been compromised by the modification. Section 
1020.30(q) does not require that owners themselves perform the 
modification, but rather that owners be responsible for assuring the 
compliance of the modified system.
    (Comment 32) One comment suggested that the party performing the 
modification be required to certify and report the modification in a 
manner similar to that required of an assembler of a new x-ray system. 
Another recommended that the party performing the modification submit a 
report as required by subpart B of 21 CFR part 1002 to the owner of the 
x-ray system.
    (Response) FDA does not see a need for the reporting of such a 
modification. The reporting of the assembly of an x-ray system is 
required to provide a mechanism for the assembler of the system to 
complete the certification that the system has been assembled according 
to the manufacturer's instructions and therefore complies with the 
standard. The compliance of any modified system can be verified during 
a routine inspection by Federal or state authorities. FDA also notes 
that the contractual arrangement between the owner and a party engaged 
by the owner to perform a modification can be structured to provide the 
owner with the necessary assurances that the party performing the 
modifications is responsible to the owner for assuring the continued 
compliance of the system. FDA concludes that there is no need to 
describe these arrangements in the standard beyond the requirement that 
the owner be responsible for assuring the continued compliance of any 
modifications to its system.
    Upon reviewing the comments relating to Sec.  1020.30(q), FDA 
decided, on its own initiative, to add a phrase to Sec.  1020.30(q)(2) 
that was not described in the proposed rule. This phrase clarifies 
where the recorded information regarding an owner-initiated 
modification is to be maintained. The phrase specifies that the 
information is to be maintained with the system records.

C. Comments on Proposed Changes to Sec.  1020.31--Radiographic 
Equipment

1. Field Limitation and Post Exposure Adjustment of Digital Image Size
    (Comment 33) One comment suggested a change in the requirement for 
beam limitation on radiographic x-ray systems that was not proposed. 
This comment recommended that automatic collimation be required for 
digital radiographic systems to preclude what it referred to as 
``digital masking'' of images obtained with the x-ray beam limiting 
device (collimator) adjusted to produce an x-ray field larger than the 
sensitive area of the digital image receptor. This comment expressed a 
concern about the operation of digital radiographic systems and the 
manner in which the x-ray field size is adjusted. Because digital 
radiographic systems permit the opportunity for post-exposure image 
manipulation, the comment expressed concern that adjustment following 
image acquisition of the area imaged or ``image cropping'' might occur, 
obscuring the fact that the x-ray field was not adjusted appropriately 
and therefore not limited to the clinical area of interest.
    (Response) FDA agrees that digital image cropping in lieu of 
appropriate x-ray field limitation could be a concern for systems that 
produce digital radiographic images with a digital image receptor used 
in place of a film/screen cassette, or for fluoroscopic systems when 
used to produce a radiographic image via the fluoroscopic image 
receptor, analogous to use of a photospot camera for analog images. For 
fluoroscopy and radiography using the fluoroscopic imaging assembly, 
proposed Sec.  1020.32(b)(4) and (b)(5) require that the x-ray field 
not exceed

[[Page 34006]]

the visible area of the image receptor by more than specific 
tolerances. These requirements for the fluoroscopic imaging assembly 
are intended to prevent imaging with the x-ray field adjusted to a size 
greater than the selected visible area of the image receptor. However, 
it may not be clear how this requirement applies to radiographic images 
at the time of later storage or display.
    For radiographic images, obtained directly using a digital 
radiographic image receptor, such as a solid-state x-ray imaging 
device, or from the fluoroscopic image receptor, the comment raised the 
question of whether some control is needed to assure that x-ray fields 
are not used when they are larger than necessary for the ultimate size 
of the either stored or displayed image.
    Neither the current standard nor the proposed amendments address 
the issue of post-exposure image cropping of the original image at the 
time of image display or image storage. In the case of a radiographic 
system, including a purely digital system, the current standard 
requires that the x-ray field size not exceed the size of the image 
receptor, meaning that portion of the image receptor area that has been 
preselected during imaging such as when using a spot-film device.
    The comment addresses the concern that the x-ray field might be 
larger than necessary to capture the area of clinical interest and that 
the individual obtaining the image could ``hide'' this fact by 
electronically cropping the digital image for storage and display. 
Thus, it would not be possible for someone reviewing the image later to 
determine that the image was obtained with an x-ray field size larger 
than necessary, resulting in unnecessary patient exposure. The comment 
suggests some type of automatic collimation to prevent this 
possibility, but does not describe the automatic system envisioned. If 
electronic cropping of digital imaging is available post exposure, it 
does not appear possible to have an automatic collimation system that 
could anticipate how such cropping might be done to the exposure.
    FDA notes that the question of electronic image cropping is a 
question that requires further exploration and discussion with the 
equipment users to determine if a requirement to address this issue is 
needed. The agency will review this issue and determine what the 
current equipment design and usage practices are. If FDA determines 
that a limitation on the ability to crop digital images is warranted 
and feasible, it will be addressed in a future proposed amendment.
2. Policy Regarding Disabled Positive Beam Limitation Systems
    (Comment 34) One State radiation control agency submitted a comment 
expressing disappointment that FDA did not propose an amendment that 
would have codified its policy regarding application of the standard to 
x-ray systems that are reassembled and that contain positive beam 
limitation systems that may have previously been disabled by the owner 
of the system.
    (Response) FDA did not propose amending the standard to include 
this clarification because it is not a performance requirement and the 
standard clearly states the performance required of stationary, 
general-purpose systems and the obligations of assemblers to install 
certified components according to the manufacturer's instructions. The 
performance standard originally required that stationary, general-
purpose x-ray systems be equipped with beam limiting devices that 
provided positive beam limitation (PBL). The standard was amended in 
1993 (58 FR 26386) to remove the requirement that stationary, general-
purpose systems be equipped with a beam limiting device providing PBL 
and permitting instead beam limiting device that provides continuous 
adjustment of the x-ray field. Questions arose regarding the 
performance required of beam limiting devices that were designed and 
certified to provide PBL when assembled into x-ray systems that were no 
longer required to provide PBL.
    The standard requires, in Sec.  1020.30(d), that assemblers of 
diagnostic x-ray systems must install certified components according to 
the instructions of the component manufacturer when these certified 
components are installed in an x-ray system. Thus, the standard 
requires that, when an assembler installs a beam limiting device, 
including one designed to provide PBL, the beam limiting device must be 
installed according to the manufacturer's instructions. That is, the 
beam limiting device must be installed such that the PBL system 
functions as designed and according to the manufacturer's instructions. 
FDA clarified this issue via communications to manufacturers, State 
radiation control agencies and others that emphasized the continuing 
requirement that any certified component be installed according to the 
manufacturer's instructions. Although the installation of a beam 
limiting device providing PBL became optional for stationary general-
purpose systems, FDA noted that the requirement to install any 
certified component according to manufacturer's instructions remained. 
Thus, a PBL system, if installed, must be installed in a manner such 
that it functions as designed, even though there is no longer a 
requirement that all stationary, general-purpose x-ray systems be 
provided with PBL. FDA, therefore, has concluded that the suggested 
amendment is not appropriate for a performance standard.

D. Comments on Proposed Changes to Sec.  1020.32--Fluoroscopic 
Equipment

1. Testing for Attenuation By the Primary Protective Barrier
    (Comment 35) One comment on Sec.  1020.32(a)(2) pointed out 
differences between FDA's testing procedures for determining compliance 
with the requirements for a primary protective barrier as part of the 
fluoroscopic imaging assembly and the testing procedure described in 
paragraph 29.207.2 of IEC standard IEC 60601-1-3. The comment noted 
that the area of the attenuation block may be insufficient for some 
modern fluoroscopic image receptors that accommodate x-ray field sizes 
greater that 20 centimeters (cm) by 20 cm.
    (Response) FDA acknowledges there may be a need for a larger 
attenuation block in some circumstances and, as described previously in 
the discussion of changes to definitions in Sec.  1020.30(b), has 
modified the definition to accommodate a larger size for the 
attenuation block.
    (Comment 36) The comment also expressed concern that, because FDA 
and IEC compliance testing procedures are different, manufacturers will 
need to perform two separate tests in order to meet both standards.
    (Response) FDA notes that its performance standard does not require 
the manufacturer to determine compliance in any particular way. Section 
1020.32(a)(2) describes how FDA will measure compliance. The 
manufacturer is free to use any test method that provides assurance 
that the product complies and is free to develop a single testing 
procedure that would assure compliance with both standards. The comment 
is incorrect, therefore, in stating that the manufacturer is required 
to perform two different sets of measurements to satisfy both 
standards.
    FDA also notes that the requirements for the thickness of the 
attenuation block and the quantitation of the amount of radiation 
transmitted by the protective barrier are different in the performance 
standard and the IEC

[[Page 34007]]

standard. The thickness differences most likely arise from the 
conversion of linear dimensions in inches (as originally used in the 
standard) to centimeters. FDA considers these differences minor and 
notes that a manufacturer may develop a single test method that assures 
compliance with both requirements.
    (Comment 37) The comment also suggested that FDA adopt the complete 
wording from the IEC standard related to the attenuation of the primary 
beam by the primary protective barrier in lieu of the current FDA 
standard.
    (Response) FDA does not believe that adoption of the IEC wording 
regarding the attenuation of the primary beam by the primary protective 
barrier is necessary. Although the two standards employ different 
approaches, including different terms, definitions, and organizational 
structure, there does not appear to be a significant conflict between 
the two standards with regard to this issue.
2. Field Limitation for Fluoroscopic Systems
    (Comment 38) One comment opposed proposed Sec.  1020.32(b)(4) and 
FDA's intent to promote continuously adjustable, circular field 
limitation in all types of fluoroscopic systems. The comment expressed 
doubts about the need for such a requirement, especially for systems 
designed for extremity imaging only, and was concerned that the 
requirement would add to maintenance costs. The comment suggested that 
a stricter requirement would be effective only if States modify their 
regulations to enforce identical requirements during the useful life of 
the equipment.
    (Response) The proposal encouraged the provision of circular or 
nearly circular collimation for fluoroscopic systems having circular 
image receptors, but does not require it. The comment provided no 
information about why a collimator providing nearly circular 
collimation would be more expensive to maintain than rectangular 
collimation. If adopted, the proposed requirement in Sec.  
1020.32(b)(4) would apply to affected equipment, regardless of when 
inspected or who is performing the inspection. FDA does not understand 
the assertion made in the comment that, under State regulations, the 
under-framed fluoroscopic field would be enlarged to fill the input 
phosphor. Review of the State regulations of the party who submitted 
the comment indicates no such requirement. Rather, this State's 
regulations require that the x-ray field not exceed the visible area of 
the image receptor. There is no requirement that the field be enlarged 
to match the size of the image receptor. The State's regulations do not 
appear to prohibit an under-framed image. FDA expects that State 
regulations will be modified to conform to the Federal standard 
because, under section 542 of the act (21 U.S.C. 360ss), States may not 
impose different requirements on an aspect of performance of an 
electronic product that is addressed by the Federal standard. FDA 
acknowledges that the benefit of the requirement will not be as great 
for fluoroscopic systems intended for examination of extremities only 
as it will be for general-purpose fluoroscopic systems. Nevertheless, 
improved collimation for these systems can reduce operator exposures 
from scattered radiation and improve image quality. The proposal does 
not require circular collimation for equipment designed only for 
extremity use. Systems with rectangular collimation will meet the 
requirement of this standard. Accordingly, no change to the proposed 
requirement was made in response to this comment.
    (Comment 39) One comment from a radiology professional organization 
stated that the proposed requirements for field limitation and 
alignment of fluoroscopic systems were acceptable. Another comment 
which specifically addressed Sec.  1020.32(b)(4)(ii)(A) and 
(b)(4)(ii)(B) asserted that the clarity of these proposed requirements 
would be improved by the addition of the words ``any linear dimension 
of'' before the words ``the visible area.''
    (Response) FDA agrees with the suggestion to add these words and 
has incorporated the change into the final performance standard.
3. Air Kerma Rates
    (Comment 40) One comment suggested a change to the wording of 
proposed Sec.  1020.32(d)(2)(iii)(B). The comment suggested adding the 
phrase ``archive of the'' before the words ``image(s) after termination 
of exposure'' to clarify that the presence of a last-image-hold feature 
is not sufficient to invoke the exception to the limit on maximum 
entrance AKR.
    (Response) FDA agrees that suggested language more accurately 
reflects the intent of the proposed paragraph. The presence of the 
last-image-hold feature, without storage of the images for later 
viewing, is not sufficient for the exception to apply. The wording of 
proposed Sec.  1020.32(d)(2)(iii)(B) has been modified accordingly.
    The agency has also decided to remove the proposed requirement that 
the limitation on the maximum AKR apply when images are recorded in 
analog format with a videotape or video-disc recorder. The proposed 
limitation on maximum AKR cannot be justified solely on the basis of 
recording technology used. The display of air kerma information will 
directly inform the user of the AKRs delivered by different modes. 
Because of the different methods and mechanisms for recording 
fluoroscopic images and the differences in the amount of incident 
radiation on the image receptor required for different clinical tasks, 
there is no consensus on appropriate maximum AKRs during recording of 
fluoroscopic images. FDA has concluded that, until such a consensus is 
developed, it is not appropriate to establish such limits. Therefore, 
the list of exceptions in Sec.  1020.32(d)(2)(iii) specifying when the 
limitation on maximum AKR does not apply has been modified to remove 
the exclusion of analog recording. Thus, the limit on maximum AKR in 
the amended standard does not apply to any mode of operation involving 
recording from the fluoroscopic image receptor for fluoroscopic systems 
manufactured after the effective date of the amendments.
    (Comment 41) One comment supported what it described as the attempt 
to establish an upper limit on AKRs during both normal and high-level 
control modes of fluoroscopy.
    (Response) This comment reflects confusion regarding the proposed 
amendments and the revision of Sec.  1020.32(d) and (e). Limits already 
exist on AKRs during normal and high-level control fluoroscopy. The 
sections are being revised for clarity; the only change is to the 
applicability of the exception to the maximum AKR limit to systems 
operated in a pulsed mode as described in the following paragraphs.
    (Comment 42) One comment noted that the distinction between 
recording fluoroscopic images via analog or digital means is not a 
reasonable means of differentiating between recording methods that 
could have different patient dose implications.
    (Response) FDA agrees that this is a legitimate concern. The 
limitation on the exception to the maximum AKR limit originally 
proposed in Sec.  1020.32(d)(2)(iii)(B) would not be an effective way 
to limit AKR as there are now available digital recording products that 
could perform the function of previous analog recording devices. The 
requirements of current Sec.  1020.32(e)(2)(i) and proposed Sec.  
1020.32(d)(2)(iii)(B) were intended to prevent bypassing the limits on 
maximum entrance AKRs by the addition of image recording devices to 
fluoroscopic systems. Rather than attempting to limit entrance AKRs in

[[Page 34008]]

this manner, FDA has concluded that the display of AKR and cumulative 
air kerma will inform operators about the amount of radiation being 
delivered during fluoroscopic procedures and that limits during 
recording cannot be appropriately justified at this time. FDA has 
therefore revised proposed Sec.  1020.32(d)(2)(iii)(B) to remove the 
last sentence that would have imposed limits during recording of 
fluoroscopic images with an analog format. The standard, as amended, 
will not place any limits on AKR during the recording of images from 
the fluoroscopic image receptor. Instead, the display of AKR and 
cumulative air kerma at the reference location, as required by Sec.  
1020.32(k), will be relied on to inform the user regarding radiation 
incident on the patient during fluoroscopic procedures.
    (Comment 43) One comment noted that the value for the maximum limit 
on AKR given in proposed Sec.  1020.32(d)(2)(iii)(C) was expressed as 
180 mGy per minute, not 176 mGy per minute, which is twice the rate of 
88 mGy per minute as specified for normal fluoroscopy mode.
    (Response) FDA agrees with this comment and has revised the limit 
to be 176 mGy per minute for consistency.
    (Comment 44) One comment suggested that additional information be 
provided to permit the AKR at the reference location for the AKR 
display to be determined for the maximum permitted AKRs where the 
latter are determined at the measurement points specified in Sec.  
1020.32(d)(3). The comment also suggested that the measurement point 
for mini C-arm systems be specified at the minimum source-skin distance 
(SSD), which is, in fact, the measurement point specified in proposed 
Sec.  1020.32(d)(3)(iv).
    (Response) The requirements in Sec.  1020.32(d) address the limit 
on the maximum AKR permitted for fluoroscopic x-ray systems. There is 
no requirement that the values obtained for AKR at the compliance 
measurement points specified in Sec.  1020.32(d)(3) be provided or 
displayed to the user. The comment appears to request that some 
comparison be made available to the user regarding the AKR at the 
compliance measurement point and the reference location for the AKR 
that is displayed according to proposed Sec.  1020.32(k). Providing 
information to the user regarding the maximum AKR that could result at 
the fluoroscopic reference location could provide additional 
information to the user prior to the use of a system. However, as this 
information will be displayed in real-time to the user during the use 
of the system, FDA does not see the need to add an additional 
requirement of the type suggested.
    (Comment 45) One comment suggested that additional language be 
added to ensure that the entrance AKR limits are met at all times by 
systems that permit variation in the source-image receptor distance.
    (Response) FDA notes that the current standard already includes 
such a requirement and, like all other requirements in Sec.  1020.32, 
this requirement applies to all fluoroscopic systems unless there is a 
specific exception stated. FDA, therefore, does not believe the 
suggested addition is needed.
4. Minimum Source-Skin Distance
    (Comment 46) One comment noted the difference in limits on the 
minimum source-skin distance permitted in the FDA performance standard 
and the limits specified in IEC standard 60601-1-3. The requirements 
addressed by the comment are those for fluoroscopic systems not 
intended for special surgical applications. Since its inception in 
1974, the performance standard has required a minimum source-skin 
distance of 38 cm for stationary fluoroscopes. The IEC standard has a 
minimum of 30 cm for fluoroscopic systems that are not intended for use 
during surgery. The comment suggested a limit of 30 cm for systems 
labeled for interventional uses. It was suggested that a minimum of 38 
cm for the source-skin distance can limit the manner of clinical use of 
C-arm fluoroscopes. The comment also acknowledged the provisions in 
both the U.S. performance standard and the IEC standard for a smaller 
minimum source-skin distance of 20 cm for systems intended for surgical 
applications. The comment noted that, although interventional uses 
might be considered surgical applications, the limit of 20 cm for 
surgical systems was too short for interventional uses.
    (Response) FDA did not propose a change to the minimum source-skin 
distance. Furthermore, no other comments suggested that the current 
minimum source-skin distance should be modified. FDA will consider the 
issue further and, if it determines that the standard should be 
modified, the agency will propose the amendment at a future time.
5. Display of Cumulative Irradiation Time
    (Comment 47) Six comments expressed very different views on the 
requirement to display the cumulative irradiation time at the 
fluoroscopist's position, as proposed in Sec.  1020.32(j)(2). Two 
comments from manufacturers and one from a State suggested that such 
information was not needed at the user's working position and, in fact, 
could be confusing to the user. In contrast, comments from two medical 
professional associations whose members are users of fluoroscopy 
systems, a medical physicist, and a State agency strongly endorsed the 
proposed requirements to display the cumulative irradiation time, along 
with the AKR and cumulative air kerma, at the user's working position.
    (Response) FDA agrees with the comments from the users of 
fluoroscopic systems and, accordingly, the final standard retains this 
requirement.
    (Comment 48) One comment emphasized the importance for the user of 
the uniformity and consistency of the display of information and two 
comments suggested that FDA require that the units of measurement and 
manner of display be specified.
    (Response) In response to these comments, FDA has revised Sec.  
1020.32(h)(2) to specify the following requirements: The display must 
show the irradiation time in minutes and tenths of minutes and such 
information must be displayed continuously; updated every 6 seconds, 
displayed within 6 seconds of termination of exposure, and displayed 
until reset. In addition, as noted in the discussion of Definitions 
mentioned previously in the document, FDA has added a definition of 
``fluoroscopic irradiation time'' to Sec.  1020.30(b) to further 
clarify the meaning of this term.
6. Audible Signal of Irradiation Time
    (Comment 49) Five comments addressed the proposed requirement that 
an audible signal sound every 5 minutes during fluoroscopy to alert the 
fluoroscopist to the passage of irradiation time. Three of these 
comments supported the proposed approach of a fixed, 5-minute interval 
between audible signals. Two of the comments specifically addressed the 
question of whether the interval between audible signals should be 
selectable by the user and recommended against such an approach, 
suggesting that a variable interval could lead to confusion. One 
comment from a manufacturer's association suggested complete 
elimination of the audible signal in view of the display of the AKR and 
cumulative air kerma to the operator and the potential for the audible 
signal to be distracting to the user. However, users of fluoroscopic 
systems supported retaining the

[[Page 34009]]

requirement of an audible signal as a feature of the equipment. One 
manufacturer commented that the proposed requirement of an audible 
signal would lead to a potential conflict with the IEC standard 60601-
2-7, ``Particular Requirements For the Safety of High-Voltage 
Generators of Diagnostic X-Ray Generators,'' which contains a 
requirement for an audible signal that sounds continuously until reset. 
The manufacturer's comment also raised a question regarding the 
specification of the interval between reset of the signal and the time 
of the next audible signal.
    (Response) FDA notes the potential conflict with IEC standard 
60601-2-7, and further notes that this requirement for an audible 
warning of elapsed fluoroscopic time predates the use of fluoroscopy in 
interventional procedures, which often require much more than 5 minutes 
of irradiation time. The need to continually reset the 5-minute timer 
and the lack of information about the cumulative fluoroscopic time 
under those circumstances indicate that the current IEC requirement 
should also be revised. FDA will work with the appropriate IEC 
committee responsible for the maintenance of IEC 60601-2-7 to encourage 
that it be revised to be consistent with the FDA proposal.
    (Comment 50) One comment suggested that the audible signal should 
be required to be reset manually because a signal of 1-second duration 
would likely be ignored.
    (Response) In view of the additional requirement for a display of 
air kerma information during a procedure, FDA does not think that a 
manual reset of the audible signal is needed or that such a requirement 
would add significantly to the safety of these systems. The users of 
fluoroscopic systems will have both the display of air kerma 
information and the periodically recurring audible signal to remind 
them of the passage of fluoroscopic irradiation time. Nevertheless, the 
standard should not prohibit a manual reset if the user desires such a 
feature. Therefore, Sec.  1020.32(j)(2) has been modified to permit, at 
the option of the manufacturer, the signal to be automatically 
terminated after 1 second or to continue sounding until manually reset. 
Manufacturers may provide both options for user selection if they wish.
7. Last-Image-Hold (LIH) Feature
    (Comment 51) Six comments supported the proposed requirement for 
the LIH feature on fluoroscopic systems. One of these comments 
questioned whether the LIH feature was necessary for small, extremity-
only fluoroscopic systems, in view of their low radiation output.
    (Response) FDA believes that, even for the small, extremity-only 
fluoroscopic systems, the LIH feature can reduce exposure to the 
patient and operator. Many of the current extremity-only systems, which 
are digital systems, already provide the LIH feature. FDA has 
determined that this requirement should apply to all fluoroscopic 
systems.
    (Comment 52) In response to the proposed requirement that images 
that are the result of the LIH display be clearly labeled as LIH 
images, two comments stated that there are other conditions during 
which confusion might exist regarding whether a displayed image is the 
result of concurrent fluoroscopic irradiation or is a display of a 
stored image. This could be a concern with systems with more than one 
image-display device. A similar concern expressed in the comments was 
that, when systems may display stored images, there may be no clear 
indication of when the fluoroscopic x-ray tube is activated. These 
comments suggested that the standard include additional requirements, 
not contained in the proposal, for a visible indication of when 
fluoroscopic irradiation is initiated and when irradiation is 
occurring. In addition, the comments suggested that the replay of 
stored images also be accompanied by a clear indication that the image 
is a replay of a stored image and not a live fluoroscopic image.
    (Response) FDA agrees it is important that the fluoroscopic system 
provide a clear indication of when x-rays are being produced. FDA notes 
that Sec.  1020.31(j) requires radiographic systems provide a visual 
``beam-on'' indicator whenever x-rays are produced. Such a requirement 
was not included in the performance standard applicable to fluoroscopic 
systems in the past because the production of the fluoroscopic image 
was previously a direct indication of the production of x-rays. 
However, with the introduction of LIH features and the serial replay of 
stored images, the display of an image on the fluoroscopic display is 
not necessarily an indication of x-ray production.
    FDA also agrees it is important that users be able to easily 
distinguish between display of a previously recorded image(s) and live-
time image. It could be a safety issue if a recorded image were 
mistaken for a ``live'' image (or vice versa). However, FDA needs to 
further consider whether the requirements suggested by the comments 
should be added to the performance standard.
    The relevant IEC standard 60601-2-7, ``Particular Requirements for 
the Safety of High-Voltage Generators of Diagnostic X-Ray Generators'' 
(Ref. 3) (see 29.2.102 Indication of Operational States, (b) Loading 
state) requires a yellow light on the control panel of the high voltage 
generator that indicates the loading state and that there be a means 
for connecting a remote indication of the loading state in continuous 
mode. This IEC standard also requires that there be a means of 
connecting an audible signaling device to indicate the instant of 
termination of loading (radiation exposure). However, these IEC 
requirements do not address the comment's concern that there be a 
requirement for a visual signal visible from anywhere in the room.
    The adequacy of the approach taken in the IEC standard is open to 
question if, in fact, there is a need for an indication of x-ray 
production during fluoroscopy at the user's position. One could ask if 
it is sufficient for systems to provide only the means for connecting a 
signal device that would be visible in the procedure room or if means 
for actually producing such a signal should be required as part of the 
system. If only the means for connection is provided, State or local 
authorities would have to require that it be used.
    The cost of adding such a display would also have to be considered, 
although FDA expects that the cost would be minor because the change 
would only require adding an indicator if the ``means for connection'' 
required by the IEC standard is already incorporated in the design. 
Manufacturers are encouraged to provide such indicators, and FDA will 
urge the development of an appropriate requirement in an IEC standard. 
In addition, FDA will consider whether such a feature should be 
included in any future amendments to the performance standard that FDA 
may develop.
8. Display of Values of Air Kerma Rate and Cumulative Air Kerma
    (Comment 53) Eight comments addressed the proposed requirement for 
the display of AKR and cumulative air kerma at the fluoroscopist's 
working position. None of these comments opposed the proposed 
requirement. One of the comments supported the concept, but questioned 
whether it is necessary to impose the requirement on small, extremity-
only fluoroscopes. One professional association specifically suggested 
that the requirement should apply to all fluoroscopic systems.

[[Page 34010]]

    (Response) FDA notes that even small, extremity-only systems can be 
used for extended surgical or interventional procedures and that the 
radiation output of some of these systems currently is significantly 
larger than the output from early versions of these types of systems. 
For these reasons, FDA has concluded that the requirement for air kerma 
display is appropriate for all fluoroscopic systems.
    (Comment 54) Four of the comments raised questions or made 
suggestions regarding the technical details and specifics of how the 
air kerma information should be described or displayed. One of the 
comments referenced the IEC standard 60601-2-43 and the manner of air 
kerma display required by that standard, but it incorrectly cited the 
requirements of that standard.
    (Response) In response to these comments, FDA has modified proposed 
Sec.  1020.32(k) to require display of the AKR at the fluoroscopist's 
working position when the x-ray tube is activated and the number of 
images produced is greater than six images per second. Furthermore, the 
value displayed is required to be updated at least once every second. 
The value of the cumulative air kerma will be required to be displayed 
either within 5 seconds of termination of an exposure, or it can be 
displayed continuously and updated at least once every second. The 
displayed values of AKR and cumulative air kerma must be clearly 
distinguishable from each other. The details of the specific display 
means are left to the manufacturer, except that the AKR must be 
displayed in units of mGy/min and the cumulative air kerma in mGy.
    (Comment 55) A comment from a radiology society suggested that the 
cumulative air kerma be displayed continuously at the operator's 
position at all times while fluoroscopy is used.
    (Response) This comment, from an organization representing users of 
fluoroscopic systems, indicates that these users desire a simultaneous 
display of both AKR and cumulative air kerma. FDA originally had 
envisioned a single display that would alternate between AKR and 
cumulative air kerma, depending on the state of the x-ray generator. 
However, this physician group indicates a preference for continuous 
update and display of the cumulative air kerma. FDA agrees that such a 
display is feasible and not likely to add significant costs to meeting 
the requirement.
    There is a potential advantage to displaying the cumulative air 
kerma only at the termination of exposure. This would provide an 
incentive to stop or interrupt the exposure to learn or view the 
cumulative exposure and thereby perhaps minimize exposure time. 
However, during most fluoroscopic procedures, the exposure is 
continually interrupted and thus the cumulative air kerma would often 
be displayed.
    After reviewing the comments received from the radiology society 
and others regarding the proposed requirement for the display of AKR 
and cumulative air kerma at the fluoroscopist's working position, FDA 
has determined that the method of display of cumulative air kerma can 
be left to the manufacturer. Either a continuous display of cumulative 
air kerma or a display following termination of exposure will provide 
the user with the necessary information.
    (Comment 56) One comment suggested that a statement be added to 
explain that the information displayed would represent the air kerma 
measured without scatter.
    (Response) FDA notes that this information was contained in the 
proposed requirement and is in revised Sec.  1020.32(k)(4).
    (Comment 57) One comment suggested that an alternative requirement 
was needed for the description of the reference location for 
fluoroscopic systems that have variable source-image receptor distance.
    (Response) FDA notes that the reference location is specified with 
respect to the table or the isocenter for a C-arm system and that, 
under Sec.  1020.32(k)(4)(ii), a manufacturer may describe an alternate 
reference location if appropriate. Therefore, FDA has concluded that 
the addition suggested by this comment is not needed.
    (Comment 58) One comment recommended that manufacturers be 
permitted to adjust or change the reference location for AKR and 
cumulative air kerma to a point specified by the clinical user of the 
system.
    (Response) This comment appears to suggest that some clinical users 
might wish to have the air kerma display indicate the air kerma at 
locations other than the location identified by the manufacturer in the 
initial design of the system. Users might desire this alternative if 
they consider some other point to be more representative of the dose to 
the patient. FDA notes that the air kerma at any other location can be 
obtained by the use of a multiplicative factor that is the square of 
the ratio of distance from the source to the reference location to the 
distance from the source to the new location. Such a factor can be 
easily calculated. Also, it is permissible for the owner of an x-ray 
system to modify (or cause to be modified) the x-ray system as long as 
the modification does not cause the system to fail to comply with the 
performance standard. Therefore, an owner could request that a system 
be modified to display the air kerma at a point different from that 
originally specified by the manufacturer, under Sec.  1020.30(q), 
provided the user instructions for that specific system are also 
appropriately modified to indicate the location of the new reference 
location to which the air kerma display is referenced. FDA would 
encourage that, for any system so modified, the modification be clearly 
posted or labeled so that all users are aware of the modification. Such 
a modification would be possible only if the manufacturer's design of 
the air kerma display system provides a means by which the calibration 
of the air kerma display could be adjusted by a factor to provide the 
requested display. FDA does not believe that it is necessary to require 
that all systems have such a capability.
    (Comment 59) Four comments expressed concern about the tolerance of 
25 percent for the deviation of the displayed values of AKR 
and cumulative air kerma from the actual values. Several of these 
comments asserted that the accuracy of the corresponding display 
requirement in IEC standard 60601-2-43 is 50 percent. They 
also pointed out that accuracy required of ionization-chamber-based 
dose-area-product meters specified by IEC standard IEC 60580 (Ref. 4) 
is 25 percent, and that other sources of error would 
combine with the basic uncertainties of a measuring instrument such as 
a dose-area-product meter to determine the air kerma at the reference 
location.
    (Response) FDA agrees that the standard should not require accuracy 
greater than is technically feasible. FDA discussed this tolerance with 
the TEPRSSC advisory committee during a public meeting and members of 
the committee expressed the opinion that the display of dose 
information should be as accurate as possible to provide a meaningful 
indication of the patient dose. These members suggested that an 
accuracy of better than 50 percent should be possible. 
After considering factors that could contribute to the uncertainty of 
the display of AKR and cumulative air kerma, and the importance of 
having as accurate an indication as technically feasible, FDA has 
concluded that a tolerance of 35 percent is appropriate. 
Accordingly,

[[Page 34011]]

proposed Sec.  1020.32(k)(7) has been revised as Sec.  1020.32(k)(6) 
and specifies a maximum uncertainty of 35 percent and a 
range of AKRs and cumulative air kerma over which this accuracy is to 
be met. Manufacturers will need to provide a schedule of maintenance 
sufficient to keep the air kerma display values within these 
tolerances.
    Also, in conjunction with considering the accuracy of the dose 
display, FDA noted a need to better describe the conditions under which 
compliance would be determined. Therefore, FDA has also included in 
Sec.  1020.32(k)(6) a specification that compliance with the accuracy 
requirement shall be determined with measurements having an irradiation 
time greater than three seconds. This condition is sufficient to allow 
for any minimum response times associated with measuring instruments.

IV. Additional Revisions of Applicability Statements and Other 
Corrections

    In section II.B of the proposed rule (62 FR 76056 at 76059), FDA 
described the need to modify the applicability statements in Sec. Sec.  
1020.31 and 1020.32 to clearly distinguish between radiographic and 
fluoroscopic imaging and to identify the type of equipment to which 
each section applies. This clarification was needed in conjunction with 
modifying the performance standard to address the new types of image 
receptors that have been introduced for fluoroscopy and radiography. As 
part of this clarification, definitions of radiography and fluoroscopy 
were also proposed.
    Although no comments were received on the proposed modifications to 
the applicability statements for Sec. Sec.  1020.31 and 1020.32, FDA 
has concluded that additional modifications of the applicability 
statements for both sections are necessary for clarity. These changes, 
which are described in the following paragraphs, are not substantive 
changes to the wording of both sections as contained in the proposed 
rule.
    The proposed rule contained a proposed Sec.  1020.30(a)(1)(i)(F) 
that added image receptors that are electrically powered or connected 
to the x-ray system, to the list of components to which the performance 
standard applies. This addition was proposed because FDA determined 
that it was necessary to include new solid-state x-ray imaging devices, 
which are being used for both radiography and fluoroscopy, in the list 
of components subject to the requirements of the performance standard.
    FDA inadvertently failed to discuss the addition of proposed Sec.  
1020.30(a)(1)(i)(F) in the preamble to the proposed rule. However, the 
application of the performance standard to the new types of image 
receptors was extensively discussed in sections II.B and II.C of the 
preamble of the proposed rule. Thus, FDA believes that its intention to 
apply the standard to these types of x-ray system components was made 
clear. No comments were received concerning this addition to Sec.  
1020.30(a); therefore, FDA has retained this proposed paragraph in the 
final rule.
    The application of solid-state x-ray imaging devices as the image 
receptors for both radiographic and fluoroscopic x-ray systems requires 
additional clarification in the performance standard regarding the 
specific requirements that apply to these components and systems 
containing them. Previously, the requirements of Sec.  1020.31 for 
radiographic systems were understood to apply to systems when x-ray 
film was used to obtain static radiographic images. The requirements of 
Sec.  1020.32 applied to fluoroscopic x-ray systems, including when the 
fluoroscopic image receptor, primarily the x-ray image intensifier 
tube, was used to record images such as during cineradiography or when 
photospot images were made. With the introduction of solid-state x-ray 
imaging devices, we now have the situation where image receptors with 
the same or very similar technology may be used in both radiographic 
and fluoroscopic x-ray systems. The solid-state x-ray imaging device 
used for fluoroscopy may also produce digital radiographic images that 
are essentially equivalent to images produced by solid-state x-ray 
imaging devices used as the image receptor in digital radiographic x-
ray systems. Such similarities can raise questions about when the 
requirements of Sec. Sec.  1020.31 or 1020.32 apply to a system using a 
solid-state x-ray imaging device to produce digital images.
    To date, this question has not received very much, if any, 
discussion in the radiology community. Contrary to the situation 
involving x-ray film and intensifying screens in an imaging cassette, 
the introduction of solid-state x-ray imaging devices, which are 
integral parts of the electronic x-ray system, raises questions as to 
what are appropriate performance requirements for these systems. FDA 
notes that there has been no consensus developed about how requirements 
such as x-ray system linearity, reproducibility, and x-ray field 
indication and alignment may need to be modified to appropriately 
assure the radiation safety performance of systems using a solid-state 
x-ray imaging device. FDA did not specifically raise these issues in 
the preamble to the proposed rule.
    As discussed previously in section III.A of this document (comment 
5), two of the organizations commenting on the proposed rule suggested 
that additional action may be needed to determine appropriate 
performance requirements for solid-state x-ray imaging devices. FDA 
agrees that further investigation and development of consensus on 
appropriate requirements for systems using solid-state x-ray imaging 
devices is needed and will pursue further discussions and interactions 
with the radiology community to better define what these requirements 
should be. However, in the meantime, clarification is needed regarding 
how the requirements of the current standard apply to systems using new 
types of x-ray image receptors. FDA has modified the introductory 
applicability statements of Sec. Sec.  1020.31 and 1020.32 to clarify 
how these requirements apply to such systems.
    In the proposed rule, the applicability statements of Sec. Sec.  
1020.31 and 1020.32 were revised to replace the reference to the x-ray 
image intensifier tube with a reference to the fluoroscopic image 
receptor.
    In this final rule, the applicability statements have been further 
revised to use the new definitions of radiography and fluoroscopy and 
to indicate that, when images are recorded using the fluoroscopic image 
receptor, the requirements of Sec.  1020.32, not Sec.  1020.31, will 
apply. Thus, if an image receptor is used for fluoroscopic imaging, the 
requirements of Sec.  1020.32 apply even when radiographic images are 
produced using the fluoroscopic image receptor. When the image receptor 
``irrespective of whether it is film-based, computed radiographic, or 
solid-state x-ray imaging digital technology'' is used only for 
radiographic imaging, the requirements of Sec.  1020.31 will apply. FDA 
notes that, if new combination radiographic and fluoroscopic system 
designs are developed that use the same image receptor for both 
fluoroscopic and all conventional radiographic images, the modified 
applicability statements would apply only the requirements of Sec.  
1020.32 to these types of systems. FDA recognizes that this particular 
application of requirements may not be the optimum approach or the most 
appropriate control for systems using new types of image receptors. 
However, until a consensus is developed regarding a different approach 
or different requirements, FDA has

[[Page 34012]]

concluded that this approach to applying the requirements of Sec. Sec.  
1020.31 and 1020.32 is appropriate. FDA will initiate efforts to 
develop a consensus in the radiology community regarding the 
appropriate requirements that should be applied to systems using solid-
state x-ray imaging devices and, if warranted, propose future revisions 
to the performance standard established by this final rule.
    FDA also notes that a typographical error regarding the statement 
of effective date in the introductory paragraph of Sec.  1020.31 has 
been corrected to read November 29, 1984, rather than November 28, 
1984. This date was originally established as November 29, 1984 in the 
final rule published in the Federal Register of August 31, 1984 (49 FR 
34698) but was incorrectly printed as November 28, 1984, in the 
revision of the standard published on May 3, 1993 (58 FR 26386).
    In addition, there was a typographical error in the text of 
proposed Sec.  1020.32(k)(5)(ii), which was intended to describe the 
alternate location for the reference location that manufacturers might 
choose to designate. This text has been corrected, so that Sec.  
1020.32(k)(4)(ii) now reads as intended, ``Alternatively, the reference 
location shall be at a point specified by the manufacturer to represent 
the location of the intersection of the x-ray beam with the patient's 
skin.''

V. Environmental Impact

    The agency has determined under 21 CFR 25.30(i) and 25.34(c) that 
this action is of a type that does not individually or cumulatively 
have a significant effect on the human environment. Therefore, neither 
an environmental assessment nor an environmental impact statement is 
required.

VI. Paperwork Reduction Act of 1995

A. Summary

    This final rule contains information collection provisions that are 
subject to review by the Office of Management and Budget (OMB) under 
the Paperwork Reduction Act of 1995 (44 U.S.C. 3501-3502). The title, 
description, and respondent description of the information collection 
provisions are shown in the following paragraphs with an estimate of 
the annual reporting burden. Included in the estimate is the time for 
reviewing instructions, searching existing data sources, gathering and 
maintaining the data needed, and completing and reviewing each 
collection of information.
    FDA received no comments related to the information collection 
requirements or the estimate of burden in response to the proposed 
rule. FDA, therefore, concludes that readers of the proposed rule 
recognized the necessity of the information to be collected, did not 
disagree with FDA's estimate of the burden, and had no suggestions of 
alternate approaches to accomplishing the goals of the proposal.

Performance Standard for Diagnostic X-Ray Systems and Their Major 
Components (21 CFR 1020.30 and 1020.32 Amended)

    Description: FDA is amending the performance standard for 
diagnostic x-ray systems by establishing, among other things, 
requirements for several new equipment features on all new fluoroscopic 
x-ray systems. In the current performance standard, Sec.  1020.30(h) 
requires that manufacturers provide to purchasers of x-ray equipment, 
and to others upon request, manuals or instruction sheets that contain 
technical and safety information. This required information is 
necessary for all purchasers (users of the equipment) to have in order 
to safely operate the equipment. Section 1020.30(h) currently describes 
the information that must be provided.
    The rule established by this document will add to Sec.  1020.30 
paragraphs (h)(5) and (h)(6) describing additional information that 
must be included in these manuals or instructions. In addition, Sec.  
1020.32(j)(4) specifies additional descriptive information to be 
included in the user manuals for fluoroscopic x-ray systems required by 
Sec.  1020.30(h). This additional information contains descriptions of 
features of the x-ray equipment required by the amendments and 
information determined to be appropriate and necessary for safe 
operation of the equipment.
    Description of Respondents: Manufacturers of fluoroscopic x-ray 
systems that introduce fluoroscopic x-ray systems into commerce 
following the effective date of these amendments. FDA estimates the 
burden of this collection of information as follows:

    Table 1.--Estimated Average Annual Reporting Burden for the First
                                 Year\1\
------------------------------------------------------------------------
                                   Annual
                       No. of     Frequency    Total      Hours    Total
  21 CFR Section    Respondents      per       Annual      per     Hours
                                 Respondent  Responses  Response
------------------------------------------------------------------------
1020.30(h)(5) and         20          10         200       180    36,000
 (h)(6) and
 1020.32(j)(4)
------------------------------------------------------------------------
\1\ There are no capital costs or operating and maintenance costs
  associated with this collection of information.


 Table 2.--Estimated Average Annual Reporting Burden for the Second and
                            Following Year\1\
------------------------------------------------------------------------
                                   Annual
                       No. of     Frequency    Total      Hours    Total
  21 CFR Section    Respondents      per       Annual      per     Hours
                                 Respondent  Responses  Response
------------------------------------------------------------------------
1020.30(h)(5) and         20           5         100       180    18,000
 (h)(6) and
 1020.32(j)(4)
------------------------------------------------------------------------
\1\ There are no capital costs or operating and maintenance costs
  associated with this collection of information.

B. Estimate of Burden

    As described in the assessment of the cost impact of the amendment 
(Ref. 5), it is estimated that there are about 20 manufacturers of 
fluoroscopic x-ray systems who market in the United States. Each of 
these manufacturers is estimated to market about 10 distinct models of 
fluoroscopic x-ray systems. Immediately following the effective date of 
the amendments, for each model of fluoroscopic x-ray system that 
manufacturers continue to market, each manufacturer will have to 
supplement the user instructions to include the additional information 
required by the amendments.

[[Page 34013]]

    Manufacturers already develop, produce, and provide x-ray system 
user manuals or instructions containing the information necessary to 
operate the systems, as well as the specific information required to be 
provided by the existing standard in Sec.  1020.30(h). Therefore, it is 
assumed that no significant additional capital, operating, or 
maintenance costs will be incurred by the manufacturers in connection 
with the provision of the newly required information. The manufacturers 
already have procedures and methods for developing and producing the 
user's manuals, and the additional information required by the 
amendments is expected to only add a few printed pages to these already 
extensive manuals or documents.
    The burden that will be imposed on manufacturers by the new 
requirements for information in the user's manuals will be the effort 
required to develop, draft, review, and approve the new information. 
The information or data to be contained within the new user 
instructions will already be available to the manufacturers from their 
design, testing, validation, or other product development documents. 
The burden will consist of gathering the relevant information from 
these documents and preparing the additional instructions from this 
information.
    It is estimated that about 3 weeks of professional staff time (120 
hours) will be required to gather the required information for a single 
model of an x-ray system. It is estimated that an additional 6 weeks 
(240 hours) of professional staff time will be required to draft, edit, 
design, layout, review, and approve the new portions of the user's 
manual or information required by the amendments. Hence, FDA estimates 
a total of 360 hours to prepare the new user information that will be 
required for each model.
    For a given manufacturer, FDA anticipates that every distinct model 
of fluoroscopic system will not require a separate development of this 
additional information. Because it is thought highly likely that 
several models of fluoroscopic x-ray systems from a given manufacturer 
will share common design aspects, it is anticipated that similar means 
for meeting the requirement for display of exposure time, AKR, and 
cumulative air kerma and the requirement for the last-image-hold 
feature will exist on multiple models of a single manufacturer's 
products. Such common design aspects for multiple models will reduce 
the burden on manufacturers to develop new user information. Hence, the 
average time required to prepare new user information for all of a 
manufacturer's models will be correspondingly reduced. FDA expects that 
the average burden will be reduced from 360 hours to about 180 hours 
per model, under the assumption that each set of user information for a 
given equipment feature design will be applicable to at least two 
different models of a manufacturer's fluoroscopic systems. Under this 
assumption, the total estimated time for preparing the new user 
information that will be required is 36,000 hours, as shown in table 1 
in the preamble of this document.
    In each succeeding year the burden will be less, as the reporting 
requirement will apply only to the new models developed and introduced 
by the manufacturers in that specific year. FDA assumes that every 2 
years each manufacturer will replace each of its models with a newer 
model requiring new user information. The multiple system applicability 
of this information is accounted for by also assuming that each new 
model only requires 180 hours of effort to develop the required 
information. These assumptions result in an estimated burden of 18,000 
hours for each of the years following the initial year of applicability 
of the amendments, as shown in table 2 of this document. The 
information collection burden of the current performance standard at 
Sec. Sec.  1020.30 and 1020.32 is approved and reported under an 
existing information collection clearance (OMB control number 0190-
0025).
    The information collection requirements in this final rule have 
been approved under OMB control number 0910-0564. This approval expires 
December 31, 2006. An agency may not conduct or sponsor, and a person 
is not required to respond to, a collection of information unless it 
displays a currently valid OMB control number.

VII. Analysis of Impacts

A. Introduction

    FDA has examined the impacts of this final rule under Executive 
Order 12866 and the Regulatory Flexibility Act (5 U.S.C. 601-612), and 
the Unfunded Mandates Reform Act of 1995 (UMRA) (Public Law 104-4) . 
Executive Order 12866 directs agencies to assess all costs and benefits 
of available regulatory alternatives and, when regulation is necessary, 
to select regulatory approaches that maximize net benefits (including 
potential economic, environmental, public health and safety, and other 
advantages; distributive impacts; and equity). The agency believes that 
this final rule is consistent with the regulatory philosophy and 
principles identified in the Executive order. In addition, the final 
rule is a significant regulatory action as defined by Executive Order 
12866 and, therefore, is subject to review.
    The Regulatory Flexibility Act requires agencies to analyze 
regulatory options that would minimize any significant impact on small 
entities. An analysis of available information suggests that costs to 
small entities are likely to be significant, as described in the 
following analysis. FDA believes that this regulation will likely have 
a significant impact on a substantial number of small entities, and it 
conducted an initial regulatory flexibility analysis (IRFA) to ensure 
that any such impacts were assessed and to alert any potentially 
impacted entities of the opportunity to submit comments. No comments 
were received regarding the impact on small entities, and the IRFA 
became the final regulatory flexibility analysis without further 
revision (see section VII.J of this document).
    Section 202(a) of the UMRA requires that agencies prepare a written 
statement, which includes an assessment of anticipated costs and 
benefits, before proposing any rule that includes any Federal mandate 
that may result in an expenditure by State, local, and tribal 
governments, in the aggregate, or by the private sector, of $100 
million (adjusted annually for inflation) in any one year. The current 
threshold after adjustment for inflation is $115 million, using the 
most current (2003) Implicit Price Deflator for the Gross Domestic 
Product. FDA does not expect this final rule to result in any 1-year 
expenditure that would meet or exceed this amount.
    The agency has conducted analyses of the final rule, including a 
consideration of alternatives, and has determined that the final rule 
is consistent with the principles set forth in the Executive order and 
in these statutes. The costs and benefits of the rule have been 
assessed in two separate analyses that are described in this section of 
the document and that were made available for review at the Division of 
Dockets Management (HFA-305), Food and Drug Administration, 5630 
Fishers Lane, rm. 1061, Rockville, MD 20852. As reviewed in the 
following paragraphs, these analyses have an estimated upper limit to 
the annual cost of $30.8 million during the first 10 years after the 
effective date of the amendments using a 7-percent annual discount rate 
and $30.1 million using a 3-percent annual discount rate. The analysis 
of benefits projects an average annual amortized pecuniary savings in 
the first 10 years after the effective date of at least $320

[[Page 34014]]

million, with an estimated 90 percent confidence interval spanning a 
range between $88.3 million and $1.160 billion using a 7-percent annual 
discount rate. The same analysis of benefits using a 3-percent annual 
discount rate resulted in annualized benefits of $715 million, with a 
90-percent confidence interval of between $197.3 million and $2.593 
billion. Table 2a of this document shows the annualized costs, 
benefits, and net benefits of the final regulation. FDA believes this 
analysis of impacts complies with Executive Order 12866 and OMB 
Circular A-4, and that the rule is a significant regulatory action as 
defined by the Executive order. Because of the preliminary nature of 
the initial cost and benefit analyses and estimates, FDA requested 
comments on any aspect of their methodologies, assumptions, and 
projections in the proposed rule. The only comments received on any 
aspect of these analyses were two comments that suggested, for two 
different reasons, that FDA had underestimated the benefits that will 
result from the amendments. FDA considered these comments and 
determined, due to the inherent uncertainty in the benefits cited, that 
revision of the estimated benefits analysis is not warranted.

              Table 2a.--Summary of Annualized Costs, Benefits, and Net Benefits of the Final Rule
                                            (in millions of dollars)
----------------------------------------------------------------------------------------------------------------
                                                     Annualized        Range of Annualized      Net Annualized
       Discount Rate          Annualized Costs        Benefits               Benefits          Benefits (Modal)
----------------------------------------------------------------------------------------------------------------
3% Annual discount rate                   $30.1              $715.6  $197.4 to $2,592.8                   $685.5
----------------------------------------------------------------------------------------------------------------
7% Annual discount rate                   $30.8              $320.3  $88.4 to $1,160.5                    $289.5
----------------------------------------------------------------------------------------------------------------

B. Objective of the Rule

    The primary objective of the rule is to improve the public health 
by reducing exposure to and detriment associated with unnecessary 
ionizing radiation from diagnostic x-ray systems, while maintaining the 
diagnostic quality of the images. The rule will meet this objective by 
requiring features on newly manufactured x-ray systems that physicians 
may use to minimize unnecessary or unnecessarily large doses of 
radiation that could result in adverse health effects to patients and 
health care personnel. Such adverse effects from x-ray exposure can 
include acute skin injury and an increased potential for cancer or 
genetic damage. The secondary objectives of this rule are to bring the 
performance standard up to date with recent and emerging technological 
advances in the design of fluoroscopic and radiographic x-ray systems 
and to assure appropriate radiation safety for these designs. The 
amendments will also align the performance standard with performance 
requirements in current international standards that were developed 
after the original publication of the performance standard in 1972. In 
several instances, the international standards contain more stringent 
requirements on aspects of system performance than the current U.S. 
performance standard. The changes will ensure that the different safety 
standards are harmonized to the extent that systems meeting one 
standard will not be in conflict with the other. Such harmonization of 
standards lessens the regulatory burdens on manufacturers desiring to 
market systems in the global market.
    The amendments will require particular x-ray equipment features 
reducing unnecessary radiation exposure. FDA believes the amendments 
are necessary because the private market may not ensure that these 
equipment features will be adopted without a government mandate for 
such features. Purchasers in health care organizations may have 
insufficient incentive to demand the more expensive x-ray equipment 
that will be required by these new amendments because benefits accrue 
mainly to patients and health care providers many years in the future. 
Patients may not demand this equipment because they lack information 
and knowledge about long-term radiation risk and about the highly 
technical nature of x-ray equipment. Hence, FDA believes these 
amendments are necessary to realize the net benefits described in the 
following analysis.

C. Risk Assessment

    The risks to health that are addressed by these amendments are the 
adverse effects of exposure to ionizing radiation that can result from 
procedures utilizing diagnostic x-ray equipment. These adverse effects 
are well-known and have been extensively studied and documented. They 
are generally categorized into two types-- ``deterministic'' and 
``stochastic.'' Deterministic effects are those that occur with 
certainty in days or weeks or months following irradiation whose 
cumulative dose exceeds a threshold characteristic of the effect. Above 
the threshold, the severity of the resulting injury increases as the 
radiation dose increases. Examples of such effects are the development 
of cataracts in the lens of the eye and skin ``burns.'' Skin is the 
tissue that often receives the highest dose from external radiation 
sources such as diagnostic or therapeutic x-ray exposure. Depending on 
the magnitude of the dose, skin injuries from radiation can range in 
severity from reddening of the skin and hair loss to more serious burn-
like effects including localized tissue death that may require skin 
grafts for treatment or may result in permanent impairment. Stochastic 
effects are those that do not occur with certainty, but if they appear, 
they generally appear as leukemia or cancer one or several decades 
after the radiation exposure. The probability of the effect occurring 
is proportional to the magnitude of the radiation dose in the tissue.
    The primary risk associated with radiation is the possibility of 
patients developing cancer years after exposure, and the magnitude of 
this cancer risk is generally regarded to increase with increasing 
radiation dose. Consistent with the conservative approach to risk 
assessment described by the National Council on Radiation Protection 
and Measurements (Ref. 6), we assume a linear relationship between 
cancer risk and dose. The slope of this relationship depends on age at 
exposure and on gender. Our benefits analysis presented in section 
VII.H of this document is based on linear interpolations of cancer 
mortality risk per whole-body equivalent dose derived from table 4-3 of 
the fifth report of the Committee on the Biological Effects of Ionizing 
Radiations (BEIR) of the National Research Council (Ref. 7). (This 
report is commonly known as ``BEIR V'' and henceforth will be 
abbreviated that way in this document.) For reasons detailed in section 
VII.H of this document, in the estimations of cancer mortality risk 
these interpolated values are reduced by

[[Page 34015]]

a dose-rate effectiveness factor (DREF) of 2 for solid cancers (Ref. 
8). The values used in our analysis are represented in the following 
graph of the excess lifetime probability of death per sievert of whole-
body equivalent dose (figure 1 of this document). Equivalent dose is 
determined from the average radiant energy absorbed per mass of tissue 
or organ exposed, where this average is multiplied by a dimensionless 
radiation weighting factor whose magnitude accounts for the detrimental 
biological effectiveness of the type of radiation; the value of the 
radiation weighting factor is unity for x rays emitted by the equipment 
covered in these regulations (Ref. 13). In the International System of 
Units, the unit of measurement of equivalent dose is joule per kilogram 
(J/kg) and is given the special name ``sievert'' (Sv) (Ref. 7). 
``Whole-body'' means that all of the organs and tissues of the body 
receive the same dose.
BILLING CODE 4160-01-S

[[Page 34016]]

[GRAPHIC] [TIFF OMITTED] TR10JN05.000

BILLING CODE 4160-01-C


[[Page 34017]]


    Based on Science Panel Report No. 9 (Ref. 8) of the Committee on 
Interagency Radiation Research and Policy (CIRRPC) of the Office of 
Science Technology and Policy of the Executive Office of the President, 
FDA underscores the overarching uncertainty in these projections with 
the following statement:
    The estimations of radiation-associated cancer deaths were derived 
from linear extrapolation of nominal risk estimates for lifetime total 
cancer mortality from doses of 0.1 Sv. Other methods of extrapolation 
to the low-dose region could yield higher or lower numerical estimates 
of cancer deaths. At this time studies of human populations exposed at 
low doses are inadequate to demonstrate the actual level of risk. There 
is scientific uncertainty about cancer risk in the low-dose region 
below the range of epidemiologic observation, and the possibility of no 
risk cannot be excluded.
    We project that the equipment features that will be required by 
three of the amendments will promote the bulk of radiation dose 
reduction and hence cancer risk reduction: (1) Displays of irradiation 
time, rate, and air kerma values; (2) more filtration of lower-energy 
x-rays; and (3) improved geometrical efficiency of the x-ray field 
achieved through tighter collimation. We assume that the display 
amendment will reduce dose on the order of 16 percent. This assumed 
value is one-half of a 32-percent dose reduction observed for several 
x-ray modalities in the United Kingdom (UK) between 1985 and 1995. We 
assume that one-half of the UK dose reduction was due to technology 
improvements alone, whereas the other half stemmed from the quality 
assurance use of reference dose levels and patient dose evaluation. The 
16-percent dose reduction that we project for the display amendment 
thus presumes facility implementation of a quality assurance program 
making use of the displayed values. This analysis and other 
assumptions--6 percent dose reduction for the filtration amendment, 1 
to 3 percent dose reduction for the collimation amendment--are detailed 
in Ref. 9. We invited comment on these assumptions in the proposed rule 
and received no objections to this approach. One comment suggested, 
based on a State's experience, that greater dose reductions would 
result from facilitating quality assurance programs by the requirement 
for air kerma display. Until recently, the principal radiation 
detriment for patients undergoing x-ray procedures was the risk of 
inducing cancer and, to a lesser extent, heritable genetic 
malformations. Since 1992, however, approximately 80 reports of serious 
radiation-induced skin injury associated with fluoroscopically-guided 
interventional therapeutic procedures have been published in the 
medical literature or reported to FDA. Many of these injuries involved 
significant morbidity for the affected patients. FDA's experience with 
reports of such adverse events leads the agency to believe that the 
number of these injuries is very likely underreported, given the total 
number of interventional procedures currently performed. Additionally, 
there is the lack of any clearly understood requirement or incentive 
for health care facilities to report such injuries. With the advance of 
fluoroscopic technology and the proliferating use of interventional 
procedures by practitioners not traditionally specializing in the 
field, and therefore not completely familiar with dose-sparing 
techniques, FDA expects an increasing risk of radiation burns that 
warrants the changes to the x-ray equipment performance standard 
obtained through the amendments.

D. Constraints on the Impact Analysis

    It is FDA's opinion that the amendments will offer public health 
benefits that warrant their costs. However, the agency had difficulty 
accessing pertinent information from stakeholders to help quantify the 
impact of the proposal and alternatives. In view of the limited 
information available with which to develop estimates of the costs and 
benefits, FDA solicited comments, data, and opinions about whether the 
potential health benefits of the amendments would justify their costs. 
FDA received only the two limited comments cited previously on this 
question and, therefore, has reached a final affirmative determination 
as to the appropriateness of the amendments based on the earlier 
analyses.
    The principal costs associated with the amendments will be the 
increased costs to produce equipment that will have the features 
required by the amendments. FDA has made an estimate of potential cost. 
The cost estimate is based on a number of assumptions designed to 
assure that the potential cost is not underestimated. FDA anticipates 
that the actual costs of these amendments may be significantly less 
than the upper-limit estimate developed. Manufacturers of diagnostic x-
ray systems were urged to provide detailed comments on the anticipated 
costs of these amendments that would enable refinement of these cost 
estimates. No additional information was received on this topic during 
the comment period.
    The benefits that are expected to result from these amendments are 
reductions in acute skin injuries and radiation-induced cancers. These 
benefits will result from two types of changes to the performance 
standard that should reduce patient dose and associated radiation 
detriment without compromising image quality.
    The first type of change involves several new equipment features 
that will directly affect the intensity or size of the x-ray field. 
These are the requirements addressing x-ray beam quality, x-ray field 
limitation, limits on maximum radiation exposure rate, and the minimum 
source-skin distance for mini C-arm fluoroscopic systems. Almost all of 
the changes that directly affect x-ray field size or intensity will 
bring the performance standard requirements into agreement with 
existing international voluntary standards. To the extent that these 
requirements are included in voluntary standards that have a growing 
influence in the international marketplace, the radiological community 
has already recognized their benefit and appropriateness. Moreover, 
harmonization within a single international framework will eliminate 
the need for manufacturers to produce more than one line of products 
for a single global marketplace.
    The second type of change that will be required by these amendments 
involves the information to be provided by the manufacturer or directly 
by the system itself that may be utilized by the operator to more 
efficiently use the x-ray system and thereby reduce patient dose. These 
new features are widely supported and anticipated by many knowledgeable 
users of fluoroscopic systems. Similar requirements were recently 
included in a new international voluntary standard.
    There is a third type of change being made to the standard. These 
changes will not have a direct benefit in terms of a reduction in 
radiation dose. Rather, they clarify the applicability of the standard, 
clarify definitions, and facilitate the application of the standard to 
new technology and x-ray system designs.

E. Baseline Conditions

    The cost of the amendments to the x-ray equipment performance 
standard will be borne primarily by manufacturers of fluoroscopic 
systems. The cost for one of the nine amendments will also affect 
manufacturers of radiographic equipment and is discussed in detail in 
Ref. 5. Therefore, this discussion will focus primarily on fluoroscopy 
(i.e., the

[[Page 34018]]

process of obtaining dynamic, real-time images of patient anatomy).
    X-ray imaging is used in medicine to obtain diagnostic information 
on patient anatomy and disease processes or to visualize the delivery 
of therapeutic interventions. X-ray imaging almost always involves a 
tradeoff between the quality of the images needed to do the imaging 
task and the magnitude of the radiation exposure required to produce 
the image. Difficult imaging tasks may require increased radiation 
exposure to produce the images unless some significant technological 
change provides the needed image quality. Therefore, it is important 
that users of x-ray systems have information regarding the radiation 
exposures required for the images that are being produced in order to 
make the appropriate risk-benefit decisions.
    Equipment meeting the new standards in the amendments will provide 
image quality and diagnostic information identical to equipment meeting 
current standards. Therefore, the clinical usefulness of the images 
provided will not change. The amendments will not affect the delivery 
of x-ray imaging services because the reasons for performing 
procedures, the number of patients having procedures, and the manner in 
which procedures are scheduled and conducted would not be changed as a 
result of the amendments. In addition, nothing in these amendments will 
adversely affect the clinical information or results obtained from 
these procedures. These amendments will result in x-ray systems having 
features that automatically provide for more efficient use of radiation 
or features that provide the physicians using the equipment with 
immediate information related to patient dose, thus enabling more 
informed and efficient use of radiation. These amendments will provide 
physicians using fluoroscopic equipment with the means to actively 
monitor the amount of radiation incident on patients and minimize 
unnecessary exposure or avoid doses that could result in radiation 
injury.
    Estimates of the annual numbers of certain fluoroscopic procedures 
performed in the United States during the years 1996 or 1997 were 
developed, as described in Ref. 9, using data from several sources. 
These numbers of specific procedures were used in the estimates of 
benefit from the amendments. To keep the estimations relatively simple 
and conservative, no attempt was made to project the future growth in 
the numbers of procedures suggested by some of the literature (Ref. 9, 
note 27, and Ref. 25). FDA estimates that over 3 million 
fluoroscopically guided interventional procedures are performed each 
year in the United States. These procedures are described as 
``interventional procedures'' because they accomplish some form of 
therapy for patients, often as an alternative to more invasive and 
risky surgical procedures. Interventional procedures may result in 
patient radiation doses in some patients that approach or exceed the 
threshold doses known to cause adverse health effects. The high doses 
occur because physicians utilize the fluoroscopic images throughout the 
entire procedure, and such procedures often require exposure times 
significantly longer than conventional diagnostic procedures to guide 
the therapy.
    FDA records indicate that about 12,000 medical diagnostic x-ray 
systems are installed in the United States each year. Of these, about 
4,200 are fluoroscopic system installations. The amendments will apply 
only to those new systems manufactured after the effective date, 
therefore affecting the 4,200 new fluoroscopic systems installed 
annually and a small fraction of current models of radiographic systems 
that do not meet the standard for x-ray beam quality.
    In modeling the x-ray equipment market in the United States for the 
purpose of developing estimates of the cost of these amendments, FDA 
estimates that there are approximately a total of 40 manufacturers of 
diagnostic x-ray systems in the United States and half of these (20) 
market fluoroscopic systems and radiographic systems. It is assumed 
that manufacturers of radiographic systems typically market 20 models 
of radiographic systems, while manufacturers of fluoroscopic systems 
market 10 different models of fluoroscopic systems. These estimates 
were developed by FDA in 2000. These estimates have not been updated 
since publication of the proposed rule as the size of the radiographic 
and fluoroscopic x-ray equipment is not expected to have changed 
significantly in the period since 2000 and in view of the uncertainty 
in the original estimates.

F. The Amendments

    The changes to the regulations may be considered as nine 
significant amendments to the current performance standard for 
diagnostic x-ray systems and other minor supporting changes to the 
standard. The nine principal amendments may be grouped into three major 
impact areas: (1) Amendments requiring changes to equipment design and 
performance that would facilitate more efficient use of radiation and 
provide means for reducing patient exposure, (2) amendments improving 
the use of fluoroscopic systems through enhanced information to users, 
and (3) amendments facilitating the application of the standard to new 
features and technologies associated with fluoroscopic systems.
    Amendments requiring equipment changes include the following: 
Changes in x-ray beam quality; provision of a means to add additional 
filtration; changes in the x-ray field limitation requirements; 
provision of displays of values of irradiation time, AKR, and 
cumulative air kerma; the display of the last fluoroscopic image 
acquired last-image-hold feature; specification of the minimum source-
skin distance for mini C-arm systems; and changes to the requirement 
concerning maximum limits on entrance AKR. Amendments that would result 
in improved information for users are those requiring additional 
information to be provided in user instruction manuals. Amendments 
facilitating the application of the standard to new technologies 
include the recognition of SSIX devices, revisions of the applicability 
sections, and establishment of additional definitions.

G. Benefits of the Amendments

    The amendments will benefit patients by enabling physicians to 
reduce fluoroscopic radiation doses and associated detriment and, 
hence, to use the radiation more efficiently to achieve medical 
objectives. The health benefits of lowering doses are reductions in the 
potential for radiation induced cancers and in the numbers of skin 
burns associated with higher levels of x-ray exposure during 
fluoroscopically-guided therapeutic procedures. FDA believes that the 
amendments will not degrade the quality of fluoroscopic images produced 
while reducing the radiation doses.
    There is widespread agreement in the radiological community that 
radiation doses to patients and staff should be kept ``as low as 
reasonably achievable'' (ALARA) as a general principle of radiation 
protection. The introduction of an increasing variety of new, 
fluoroscopically-guided interventional procedures, as alternatives to 
more invasive surgical procedures or as totally new therapies, and the 
use of a variety of new devices and therapies that are used with 
fluoroscopic guidance are resulting in significant increases in the 
number of fluoroscopically-guided interventional procedures with long 
irradiation times. Thus, the growing number of patients that are 
potentially at risk for acute and

[[Page 34019]]

long-term radiation injury makes it important to provide fluoroscopic 
systems with features that will assist in reducing the radiation to 
patients while continuing to accomplish the medical objectives of the 
needed procedures.
    The amendments will require that fluoroscopic x-ray systems provide 
equipment features that directly enable the user to reduce radiation 
doses and maintain them ALARA. Furthermore, the amendments will require 
provision of information to the user of the equipment in the form of 
additional information in the user's manual or instructions to enable 
improved use in a manner that minimizes patient exposures and, by 
extension, occupational exposures to medical staff.
    There also is widespread agreement that radiation exposures during 
fluoroscopy are not optimized. For example, data from the 1991 
Nationwide Evaluation of X-Ray Trends (NEXT) surveys of fluoroscopic x-
ray systems used for upper gastrointestinal tract examinations (upper 
GI exam) indicate that the mean entrance AKR is typically 5 cGy/min for 
an adult patient (Ref. 10). Properly maintained and adjusted 
fluoroscopic systems are expected to be able to perform the imaging 
tasks associated with the upper GI exam with an entrance AKR of 2 cGy/
min or less (Ref. 11). The NEXT survey data indicate significant room 
for improvement in this aspect of fluoroscopic system performance. The 
total patient dose could be significantly reduced were the entrance AKR 
lowered to what is currently reasonably achievable, and the features 
required by the amendments will facilitate this reduction.
    The new, required features of last-image-hold and real-time display 
of entrance AKR and cumulative entrance air kerma values are intended 
to provide fluoroscopists with means to better limit the patient 
radiation exposure. The last-image-hold feature will permit 
decisionmaking regarding the procedure underway while visualizing the 
anatomy without continuing to expose the patient. The air kerma- and 
AKR-value displays will provide real-time feedback to the 
fluoroscopists and are anticipated to result in improved fluoroscopist 
performance to limit radiation dose based on the immediate availability 
of information regarding that dose. Realization of the potential dose 
reduction benefits will require fluoroscopists to take advantage of 
these new features and optimize the way they use fluoroscopic systems.
    The potential impact of the change in the beam quality requirement, 
which will apply to most radiographic and all fluoroscopic systems, can 
be seen from the data on beam quality obtained from FDA's Compliance 
Testing Program for the current standard. Between January 1, 1996, and 
December 31, 2000, FDA conducted 4,832 tests of beam quality, that is, 
measurement of the HVL of the beam for newly-installed x-ray systems. 
Of these tests, only 15 systems did not meet the current HVL or beam 
quality requirement. If the requirements for HVL contained in these 
amendments had been used as the criteria for compliance, only 698 
systems or 14.4 percent of the systems tested would have been found not 
to have complied. This result suggests that, at a minimum, 
approximately 15 percent of recently installed medical x-ray systems 
would have their beam quality improved and patient exposures reduced 
were the new requirement in place and applicable to them.
    Numerous examples are available in the literature that illustrate 
the potential reduction in patient dose, while preserving image 
quality, that can result from increased x-ray beam filtration. 
Reference 12 demonstrates that the addition of 1.5 to 2.0 mm Al as 
additional filtration, which is the change required to enable systems 
that just meet the current requirement to meet the new HVL requirement, 
will result in about a 30-percent reduction in entrance air kerma and 
about a 15 percent reduction in the integral dose for the fluoroscopic 
examination modeled in the paper at 80 kVp tube potential. Reduction in 
entrance skin dose (entrance air kerma) is relevant to reducing the 
risk of deterministic injuries to the skin, while a reduction in the 
integral dose is directly related to a reduction in the risk of 
stochastic effects such as cancer induction. Other authors have 
described dose reductions of a similar magnitude from increasing 
filtration for radiographic systems.
    The requirements in these amendments implement many of the 
suggestions and recommendations developed by members of the 
radiological community at the 1992 Workshop on Fluoroscopy sponsored by 
the American College of Radiology and FDA (Ref. 11). The 
recommendations from this workshop stressed the need to provide users 
of fluoroscopy with improved features enabling more informed use of 
this increasingly complex equipment. In addition, three radiological 
professional organizations indicated their opinions to FDA that 
radiologists would use the new features to better manage patient 
radiation exposure.

H. Estimation of Benefits

    Projected benefits are quantified in table 3 of this document in 
terms of: (1) Collective dose savings, (2) numbers of lives spared 
premature death associated with radiation-induced cancer, (3) 
collective years of life spared premature death, (4) numbers of reports 
of fluoroscopic skin burns precluded, and (5) pecuniary estimates 
associated with the preceding four items. The estimates represent 
average annual benefits projected to ramp up during a 10-year interval 
in which new fluoroscopic systems conforming to the new rules are 
phased into use in the United States. (FDA assumes that 10 years after 
the effective date of the new rules all fluoroscopic systems then in 
use will conform to those rules and that associated recurring benefits 
will continue to accrue at constant rates.) Annual pecuniary estimates 
that are averaged over the 10-year ramp-up interval and that are 
associated with prevention of cancer incidence, preclusion of premature 
mortality, and obviation of cancer treatment are based on the projected 
numbers of lives spared premature death. These pecuniary estimates are 
valued in current dollars using a 7-percent and, separately, using a 3-
percent discount rate covering the identical 10-year evaluation period 
used in the cost analysis. (See section VII.I of this document.) Life 
benefits would be realized 20 years following exposure (after a period 
of 10 years of cancer latency followed by a period of 10 years of 
survival).

                          Table 3.--Projections of Annual Benefits in the United States
for display, collimation, and filtration rules applied to percutaneous transluminal coronary angioplasty (PTCA),
 cardiac catheterization with coronary arteriography or angiography (CA), and upper gastrointestinal fluoroscopy
                                                (UGI) procedures
----------------------------------------------------------------------------------------------------------------
                                                                                                       95th
                                                                     5th Percentile      Mode       Percentile
----------------------------------------------------------------------------------------------------------------
Average Annual Dose and Life Savings in the First 10 Years After     ..............  ...........  ..............
 Effective Date of Rule
----------------------------------------------------------------------------------------------------------------

[[Page 34020]]

 
  Collective dose savings (person-sievert)                                    3,202        7,231          16,330
----------------------------------------------------------------------------------------------------------------
  Number of lives spared premature death from cancer                             62          223             808
----------------------------------------------------------------------------------------------------------------
  Years of life spared premature death from cancer                            1,131        4,094          14,818
----------------------------------------------------------------------------------------------------------------
  Number of reported skin burns precluded                                       0.5          1.1             2.4
----------------------------------------------------------------------------------------------------------------
Average Annual Amortized Pecuniary Savings in the First 10 Years
 After Effective Date of Rule                                                      7% Discount Rate
----------------------------------------------------------------------------------------------------------------
  Prevention of premature death from cancer ($ millions)                      78.61       285.03        1,032.75
----------------------------------------------------------------------------------------------------------------
  Obviation of cancer treatment ($ millions)                                   9.71        35.21          127.56
----------------------------------------------------------------------------------------------------------------
  Obviation of radiation burn treatment and loss precluded ($                  0.03         0.07            0.16
   millions)\1\
----------------------------------------------------------------------------------------------------------------
  Total ($ millions)                                                          88.35       320.31        1,160.00
----------------------------------------------------------------------------------------------------------------
Average Annual Amortized Pecuniary Savings in the First 10 Years
 After Effective Date of Rule                                                      3% Discount Rate
----------------------------------------------------------------------------------------------------------------
  Prevention of premature death from cancer ($ millions)                     178.99       649.02        2,351.60
----------------------------------------------------------------------------------------------------------------
  Obviation of cancer treatment ($ millions)                                  18.34        66.52          241.01
----------------------------------------------------------------------------------------------------------------
  Obviation of radiation burn treatment and loss precluded ($                  0.03         0.07            0.16
   millions)\1\
----------------------------------------------------------------------------------------------------------------
  Total ($ millions)                                                         197.36       715.61        2,592.77
----------------------------------------------------------------------------------------------------------------
\1\ There is no amortization for savings associated with obviation of radiation burn treatment and loss because
  the interval for latency, presentation, and treatment of skin injury generally occurs within a year of
  radiation exposure.

    Columns in table 3 of this document labeled ``Mode,'' ``5th 
Percentile,'' and ``95th Percentile'' categorize the results of a 
sensitivity analysis performed to account for uncertainties in the 
principal variables used to compute the data contained in the rows of 
table 3. The columns correspond to the expected (mode) and extremum 
values of 90-percent confidence intervals associated with the estimated 
benefits. Estimation of these uncertainties is discussed following 
descriptions of the row categories in table 3.
    Collective dose savings (quantified in units of person-Sv) are the 
estimated reductions in radiation dose to the U.S. population projected 
to result following implementation of the amended regulations. 
Collective dose savings are evaluated in terms of the number of persons 
receiving a procedure (Ref. 9, notes 26 and 29, and Ref. 24) multiplied 
by the associated effective dose reduction (quantified in units of Sv) 
per procedure (Ref. 9, notes 28 and 42). The unit ``person-Sv'' is a 
product of the number of persons receiving a procedure and the number 
of Sv per procedure, where Sv is the unit of measurement of effective 
dose as well as equivalent dose, defined previously. Effective dose is 
the weighted sum of equivalent doses in all of the organs; it 
represents a level of radiation detriment equal to that for whole-body 
irradiation (Ref. 13), and we use it as an approximation of whole-body 
equivalent dose. Estimates of effective dose reduction from current 
levels that will result from the amendments are 16 percent for the air-
kerma rate and cumulative air-kerma display requirement, 6 percent for 
the requirement for increased minimum x-ray filtration, and 1 to 3 
percent for the requirement that would improve collimation of the x-ray 
field (Ref. 9, notes 9 through 13 and 18 through 25, and Refs. 12 and 
15 through 23).
    The number of lives spared premature death is the number of 
statistical deaths projected to be avoided as a result of the 
collective dose savings. It is essentially the product of the estimated 
collective dose savings described in the preceding paragraph and the 
radiation-associated mortality risk per Sv, represented in figure 1 of 
this document, summed for each gender over all ages at exposure. As 
illustrated in the Ref. 9 slide entitled ``Annual Life Benefit 
Projections in the U.S.,'' age and gender dependences are incorporated 
into the estimation of the number of lives spared premature death as 
well as into the estimation of collective dose savings and years of 
life spared premature death from cancer.
    The years of life spared premature death from cancer is a 
projection evaluated as the product of the number of lives spared 
premature death from cancer and the difference between the actuarial 
number of years of life remaining and the 20-year combined interval of 
cancer latency and survival.
    The number of skin burns precluded is projected as the percentage 
dose reduction multiplied by the number of skin burns reported to FDA 
annually, which averages approximately 8.6 reports. It is assumed that 
the fraction of skin doses exceeding the threshold for skin injury 
would be reduced in proportion to the effective-dose reduction 
(approximately 25 percent) projected for procedures of PTCA and CA and 
that therefore the number of skin burns would be reduced in the same 
proportion.
    Estimates of average annual amortized pecuniary savings in the 
first 10 years after the effective date of the rule are evaluated as 
the respective products of two factors: (1) The projected numbers of 
lives spared premature death from cancer (with which obviation of 
cancer treatment is also associated) and (2) the monetary savings per 
single case associated with either prevention of premature death from 
cancer or obviation of cancer treatment. Pecuniary savings associated 
with obviation of radiation burn treatment and loss are evaluated 
simply as the product of the

[[Page 34021]]

projected number of reported skin burns precluded and the estimated 
pecuniary savings associated with each case of radiation burn treatment 
and loss precluded; although the savings associated with radiation 
burns are averaged over the first 10 years after the effective date of 
the rule, they are not amortized because the interval for latency, 
presentation, and treatment of skin injury generally occurs within a 
year of radiation exposure.
    Based on an economic model of society's willingness to pay (WTP) a 
premium for high-risk jobs, FDA associates a value of $5 million for 
each statistical death avoided (Ref. 9, notes 54 through 56 and Refs. 
26 through 28).
    Savings of $25,000 for preclusion of each cancer treatment are 
estimated as follows: According to data of the U.S. National Cancer 
Institute (Ref. 9, note 59, and Ref. 29), 75 percent of all cancers are 
either stage 1 or 2 at the time of presentation. Per Ref. 9, note 60 
(Ref. 30), these cancers have annual treatment costs of $23,000 to 
$28,000. In situ cancers are less expensive, and stage 3 and 4 cancers 
cost $50,000 to $60,000 annually to treat. (Also see Ref. 9, note 61, 
and Ref. 31.) For the FDA analysis, the annual treatment cost is 
estimated to be that associated with the modal stage and was estimated 
to be $25,000.
    Savings of $5,000 for precluding each case of cancer's 
psychological impact are estimated as follows: Psychological impact of 
dread, anxiety, or depression has long been noted in cancer treatment 
research (e.g., see Ref. 9, notes 63 through 65, and Refs. 32 through 
34). This literature indicates that symptoms associated with mental 
well-being contribute as much as 8 percent to one's overall sense of 
health. Of the sense of psychological well-being, depression scales 
have shown that worries about personal health account for approximately 
one sixth of the 8 percent contribution, where other contributors 
include factors associated with family, finances, work, relationships, 
etc. Therefore, worries and concerns about personal health contribute 
approximately 1.3 percent to one's sense of personal well-being. 
Another way to put it is that society's WTP to avoid such worries is 
approximately 1.3 percent of overall health costs. The WTP for overall 
health is derived from the estimated annual WTP of $5 million to avoid 
a statistical death (Ref. 9, notes 54 through 56, and Refs. 26 through 
28). This value was derived from blue-collar males of about 30 years of 
age whose life expectancy is 41.3 years (adjusted for future expected 
bed and nonbed disability per Ref. 9, notes 66 and 67, and Refs. 35 and 
36). Amortization of $5 million across 41.3 years at a discount rate of 
7 percent implies a WTP of $373,000 per quality adjusted life-year 
(QALY). 1.3 percent of this QALY is approximately $5,000 per year for 
society's WTP to avoid the sense of psychological dread associated with 
concerns about personal health generated by cancer treatments.
    Savings of $67,600 for each case of radiation burn treatment and 
loss precluded are estimated as follows: Survey data on radiation burns 
indicate an average medical treatment cost of $23,000 and an average 
work-loss cost of $20,700 (Ref. 9, note 69, and Ref. 37). Costs of pain 
and suffering are estimated from an index of the quality of well-being, 
where 1.0000 indicates perfect health, 0.0000 death (Ref. 9 notes 63, 
66, and 70, and Refs. 32, 35, and 38). Relative functionality is first 
based on mobility (ranging from driving a car without help to being in 
a special care unit), social activity (ranging from working to needing 
help with self-care), and physical activity (ranging from walking 
without problems to staying in bed). Each state has been assigned a 
relative wellness and is adjusted according to the cause of the state 
(e.g., bedridden with a stomach ache versus bedridden with a broken 
leg). For the purpose of this analysis, FDA assigns two functional 
states to radiation burns: (1) Two weeks of serious debilitation 
(relative wellness value 0.3599) and (2) four weeks of functional 
distress with some activity (relative wellness value 0.5108). An annual 
amortized average value of $373,000 for the societal WTP for a QALY 
equals about $7,200 per week for a quality adjusted life week, which 
corresponds to the base 1.0000 in the well-being index. The estimate of 
the expected WTP to avoid a radiation burn is [2 x $7,200 x (1.0000 - 
0.3599)] + [4 x $7,200 x (1.0000 - 0.5108)] = $23,200. Adding this 
value to medical treatment and work-loss costs results in a cost per 
burn of $67,600.
    For the most part, these projections are based on a benefits 
analysis (Ref. 9, available at http://www.fda.gov/cdrh/radhlth/scifor01f.pdf or http://www.fda.gov/cdrh/radhlth/021501_xray.html) 
whose domain is intended to be representative but not exhaustive of 
prospective savings. To keep the analysis finite and manageable, it is 
limited to the three amendments (see sections II.E, II.F, and II.K of 
the proposed rule) that would most reduce radiation dose in several of 
the most common fluoroscopic procedures. The procedures considered are 
those of PTCA, CA, and UGI. There are other very highly-utilized 
fluoroscopic procedures, for example, the barium enema examination, 
whose dose savings might be of comparable magnitude to those of UGI, 
that are not included at all in this analysis. The three amendments 
considered would require new fluoroscopic x-ray systems to: (1) Display 
the rate, time, and cumulative total of radiation emission; (2) 
collimate the x-ray beam more efficiently; and (3) filter out more of 
the low energy x-ray photons from the x-ray beam. New requirements for 
the source-skin distance for small C-arm fluoroscopes (see section II.J 
of the proposed rule) and for provision of the last-image-hold feature 
on all fluoroscopic systems (see section II.L of the proposed rule) 
will also directly reduce dose, but their dose reductions are expected 
to be much smaller than those associated with the preceding changes. 
The remaining amendments can be characterized as clarifications of the 
applicability of the standard, changes in definitions, corrections of 
errors, and other changes that contribute generally to the 
effectiveness of implementation of the standard.
    Most of the assumptions, rationales, and data sources underlying 
the benefit projections are explicitly detailed in Ref. 9 and its 
notes. That analysis, however, is incomplete insofar as it refers only 
to a single set of point estimates employing the BEIR V mortality risk 
estimates, which presume a dose-rate effectiveness factor (DREF) equal 
to unity; the DREF is defined as ``a factor by which the effect caused 
by a specific dose of radiation changes at low as compared to high dose 
rates'' (Ref. 7). For the sensitivity analysis whose results are 
tabulated in table 3 of this document, several additional assumptions 
are invoked. Among the most important of the underpinnings of the 
analysis are the projected percentage dose reductions corresponding to 
the three amendments considered and the dependence on the risk 
estimates for cancer mortality from BEIR V (Ref. 7). For the former, 
FDA assumes a relative uncertainty of a factor of 2 (lower or higher) 
to represent the range in projected dose reductions consistent with a 
range of confidence of about 90 percent in the findings and assumptions 
(Ref. 9).
    With respect to the dependence on the BEIR V estimates, FDA follows 
two recommendations of the Office of Science and Technology Policy 
(OSTP) CIRRPC Science Panel Report No. 9 (Ref. 8) that represent the 
Federal consensus position for radiation risk benefit evaluation: 
First, we apply a value of 2 as the DREF in the projections of numbers 
of solid, non-leukemia cancers. Adopting a DREF value of 2 in

[[Page 34022]]

the analysis nearly halves the Ref. 9 modal point projections of the 
numbers of lives and years of life spared premature death from cancer. 
A DREF value of 2 implies that diagnostic or interventional fluoroscopy 
is a relatively low dose-rate modality. There are ambiguous assessments 
of that proposition: Although BEIR V (Ref. 7, pp. 171 and 220) 
considers most medical x-ray exposures to correspond to high-dose rates 
(for which the DREF is assumed to equal 1 for solid cancers), 
International Commission on Radiological Protection (ICRP) Publication 
73 (Ref. 13, p. 6) states just as unequivocally that risk factors 
reduced by a DREF larger than 1 (i.e., for low dose-rate modalities) 
``are appropriate for all diagnostic doses and to most of the doses in 
tissues remote from the target tissues in radiotherapy.'' Recognizing 
these contrary views of the detrimental biological effectiveness 
associated with the rates of delivery of fluoroscopic radiation, we 
assume a factor of 2 uncertainty in the DREF to span a 90-percent range 
of confidence and incorporate that uncertainty into the sensitivity 
analysis. The second recommendation that FDA adopts from CIRPPC Panel 
Report No. 9 (Ref. 8) is the interpretation that a factor of 2 relative 
uncertainty represents the BEIR V Committee's estimation of the 90-
percent confidence interval for mortality risk estimates (Ref. 7). The 
latter value also agrees with that in the recent review of the United 
Nations Scientific Committee on the Effects of Atomic Radiation in the 
``UNSCEAR 2000 Report'' (Ref. 14).
    All of the contributions of relative uncertainty appropriate for 
the projections of collective dose savings, lives and years of life 
spared premature death associated with radiation-induced cancer, 
numbers of reports of fluoroscopic skin burns precluded, and associated 
pecuniary estimates are summed in quadrature. For the projected 
collective dose savings, the root quadrature sum yields an overall 
estimated relative uncertainty of a factor of 2.3 lower and higher than 
the modal point estimates of the projected savings. These values 
represent, respectively, the 5th and 95th percentile points of a 90 
percent confidence interval. For the projected number of lives and 
years of life spared premature death, the overall estimated relative 
uncertainty is a factor of 3.6 lower and higher spanning a 90 percent 
confidence interval. Hence, these factors account for the principal 
sources of uncertainty in the projected dose reductions, in DREF, and 
in the mortality risk estimates. Applied to the sensitivity analysis, 
these relative factors of uncertainty comprise the bounds of 
variability within which the true values of table 3 quantities reside, 
at a 90-percent confidence level and under the modeling assumptions and 
discount rates indicated in preceding paragraphs of this document.

I. Costs of Implementing the Regulation

    Costs to manufacturers of fluoroscopic and radiographic systems 
will increase due to these proposals. FDA will also experience costs 
for increased compliance activities. Some costs represent one-time 
expenditures to develop new designs or manufacturing processes to 
incorporate the regulatory changes. Other costs are the ongoing costs 
of providing improved equipment performance and features with each 
installed unit. FDA developed unit cost estimates for each required 
activity and multiplied the respective unit cost by the relevant 
variables in the affected industry segment. One-time costs are 
amortized over the estimated useful life of a fluoroscopy system (10 
years) using a 7-percent discount rate. This allows costs to be 
analyzed as average annualized costs as well as first-year 
expenditures. FDA developed these cost estimates based on its 
experience with the industry and its knowledge regarding design and 
manufacturing practices of the industry. Initially, gross, upper-bound 
estimates were selected to ensure that expected costs were adequately 
addressed. The initial assumptions and estimates were posted on FDA's 
Web site and circulated to the affected industry for comment in July 
2000. FDA received no comments on these initial, upper-bound estimates 
and therefore believes that they were generally in line with industry 
expectations. Since then, in order to refine the estimates to provide a 
more accurate representation of the upper-bound costs of the 
amendments, FDA reexamined its estimating assumptions and reduced some 
unit cost figures based on the expectation that future economies of 
scale would reduce the expense of some required features. This section 
presents a brief discussion of the cost estimates. A detailed 
description of this analysis is given in Ref. 5.
    FDA has no information, indication, or economic presumption on 
whether costs estimated to be borne by manufacturers would be passed on 
to purchasers. The cost analysis therefore is limited to those parties 
who would be directly affected by the adoption of the amendments, 
namely, manufacturers and FDA itself. In the proposed rule, FDA 
requested information on the costs that would be imposed by these new 
requirements that would aid in refining the cost estimates. FDA 
received no comments or additional information on these costs.
1. Costs Associated With Requirements Affecting Equipment Design
    The agency estimates that approximately one-half (20) of the 
manufacturers of x-ray systems will have to make design and 
manufacturing changes to comply with the revised beam quality 
requirements. It is estimated that a total of 200 x-ray models will be 
affected, with a one-time cost of at most $20,000 per model. These 
numbers result in an estimated first year expenditure of $4.0 million 
to redesign systems to meet the new beam quality requirement.
    It will be necessary for manufacturers of fluoroscopic systems 
equipped with x-ray tubes with high heat capacity to redesign some 
systems to provide a means to add additional beam filtration. FDA 
estimates a design cost of $50,000 per model. A total of 100 models are 
likely to be affected for a one-time cost of $5.0 million to 
fluoroscopic system manufacturers. In addition, each system will cost 
more to manufacture because of the increased costs for components to 
provide the added feature. The increased cost of this added feature is 
estimated at $1,000 per fluoroscopic system. A total of 650 
fluoroscopic systems are estimated to be installed annually with high 
heat capacity x-ray tubes, resulting in a total of $0.65 million in 
increased annual costs.
    Modification of x-ray systems to meet the revised requirement for 
field limitation will entail either changes in installation and 
adjustment procedures or redesign of systems. Each fluoroscopic system 
will need either modification in the adjustment procedure for the 
collimators (for which new installation and adjustment procedures will 
be developed at an estimated one-time cost of $20,000 per model) or 
collimators will need to be redesigned at an estimated cost of $50,000 
per model. FDA has assumed that half of all fluoroscopic x-ray system 
models (5 models each for 20 manufacturers) will need modifications to 
meet the new requirement, while the remainder will either meet the new 
requirement or could meet it through very minor modifications in the 
collimator adjustment procedure. For those system models not meeting 
the new requirement, it is assumed that a redesign of the collimator 
system is required at a cost of about $50,000 per model, leading to an 
upper-bound estimate of the total redesign cost of $5.0 million (20 
manufacturers x 5

[[Page 34023]]

models x $50,000). All stationary fluoroscopic systems will most likely 
need redesigned collimators that will add an estimated additional 
$2,000 per new system due to increased complexity of the collimator. An 
annual industry cost increase of $5.0 million accounts for all 2,500 
annual installations of systems with these more expensive collimators.
    The modification of the requirement limiting the maximum entrance 
AKR and removal of the exception to the limit during recording of 
images will only affect the adjustment of newly-installed systems 
having such recording capability. This requirement is not expected to 
impose significant costs.
    FDA is requiring that all fluoroscopic systems include displays of 
irradiation time, AKR, and cumulative air kerma to assist operators in 
keeping track of patient exposures and avoiding overexposures. Each 
model of fluoroscopic system will need to be redesigned (at a maximum 
estimated cost of $50,000 per model) for an estimated one-time cost of 
$10.0 million (200 models x $50,000). Accessory or add-on equipment for 
existing fluoroscopic systems that provide similar information are 
currently available for an additional cost of over $10,000 per system. 
However, FDA expects the average manufacturing cost of including such a 
feature as an integral feature of a fluoroscopic system to be less than 
$4,000 per system, due to achievable economies of scale and integration 
with other system computer capabilities. This assumption produces an 
annual cost increase of $16.8 million (4,200 annual installations x 
$4,000).
    The amendments will require that all newly-manufactured 
fluoroscopic systems be provided with LIH capability. FDA expects that 
10 fluoroscopic system manufacturers will need to redesign their 
systems to include this technology at a maximum cost of $100,000 per 
manufacturer. Total one-time design costs will equal $1.0 million for 
the industry (10 manufacturers x $100,000). It is estimated that about 
half of the new systems installed will already be equipped with this 
feature. Thus, about half of the newly-installed systems that currently 
do not provide this feature will need it. FDA estimates that the cost 
will be an additional $2,000 for each system required to have this 
feature. Thus, annual costs will increase by $4.2 million (2,100 annual 
systems x $2,000).
    The clarification of the requirement for minimum source-skin 
distance for small C-arm systems is anticipated to require redesign of 
several of these systems. As there are only three manufacturers of 
these systems, and the redesign costs are estimated to be no more than 
$50,000 per system, the total one-time cost for this change will be 
$0.2 million. The average annualized cost of this change will be 
negligible.
    In summary, total industry costs for compliance with the amendments 
in the area of equipment design include onetime costs of $25.2 million. 
This total equals an average annualized cost (7-percent discount rate 
over 10 years) of $3.6 million. The average annualized cost using a 3-
percent discount rate over 10 years equals $3.0 million. In addition, 
annual recurring costs for new equipment features associated with these 
provisions are expected to equal $26.7 million.
2. Costs Associated With Additional Information for Users
    The amendments will require that additional information be provided 
in the user instructions regarding fluoroscopic systems. FDA has 
estimated that each model of fluoroscopic system will need a revised 
and augmented instruction manual at a cost of less than $5,000 per 
model. This is equal to a maximum one-time cost of $1.0 million (200 
models of fluoroscopic systems x $5,000) and implies maximum average 
annualized costs of $0.14 million (7-percent discount rate) or $0.12 
million (3-percent discount rate). In addition, each newly-installed 
system will include an improved instruction manual. FDA estimates a 
cost of $20 per manual for printing and distribution of the required 
additional information. Each of the 4,200 installed fluoroscopy systems 
will include a revised manual for an annual cost of approximately $0.1 
million.
    Related to the requirements for additional information is the 
change of the quantity used to describe the radiation produced by the 
x-ray system. Because the change to use of the quantity air kerma does 
not require any changes or actions on the part of manufacturers or 
users, there is no significant cost associated with it.
3. Costs Associated With Clarifications and Adaptations to New 
Technologies
    The new definitions and clarifications of applicability for the 
performance standard do not pose any significant new or additional 
costs on manufacturers.
4. FDA Costs Associated With Compliance Activities
    FDA costs will increase due to the increased compliance activities 
that will result from these regulations. In addition, FDA will 
experience implementation costs in developing and publicizing the new 
requirements. FDA has estimated that approximately five full-time 
equivalent employees (FTEs) will be required to implement the 
regulations and conduct training of field inspectors. Using the current 
estimate of $117,000 per FTE, the one-time cost of implementation to 
FDA is approximately $0.6 million. Amortizing this cost over a 10-year 
evaluation period using 7- and 3-percent discount rates results in 
average annualized costs of about $0.1 million. Ongoing costs of annual 
compliance activities are expected to require about three FTEs, or a 
little more than $0.3 million per year.
5. Total Costs of the Regulation
    The estimated costs of the amendments identified as having any 
significant cost impact are summarized in table 4 of this document. The 
costs are identified as nonrecurring costs that must be met initially 
or as annual costs associated with continued production of systems 
meeting the requirements or additional annual enforcement of the 
amendments. The total annualized cost of the regulations (averaged over 
10 years using a 7-percent discount rate) equals $30.8 million, of 
which $30.4 million will be borne by manufacturers. The annualized 
estimate of $30.8 million represents amortization of first year costs 
of $53.8 million and expenditures from years 2 through 10 of $27 
million annually. If costs are amortized using a 3-percent discount 
rate, annualized costs equal $30.1 million. The sections listed in the 
left-hand column of table 4 of this document refer to sections of the 
proposed rule.

                                    Table 4.--Summary of Costs of Amendments
----------------------------------------------------------------------------------------------------------------
 Section of the Proposed   Nonrecurring Costs                            Annual Costs to
Rule Preamble Describing   to Manufacturers ($   Nonrecurring Costs     Manufacturers ($     Annual Costs to FDA
      the Amendment             millions)        to FDA ($ millions)        millions)           ($ millions)
----------------------------------------------------------------------------------------------------------------
II.A                            none                     0.0059             none                  none
----------------------------------------------------------------------------------------------------------------

[[Page 34024]]

 
II.B                            none                     0.0324             none                  none
----------------------------------------------------------------------------------------------------------------
II.D                               1.0                none                     0.084                 0.0117
----------------------------------------------------------------------------------------------------------------
II.E                               9.0                   0.0117                0.650              none
----------------------------------------------------------------------------------------------------------------
II.F                               5.0                   0.0468                5.0                none
----------------------------------------------------------------------------------------------------------------
II.G, II.H, and II.I            none                  none                  none                  none
----------------------------------------------------------------------------------------------------------------
II.J                               0.150                 0.0234             none                  none
----------------------------------------------------------------------------------------------------------------
II.K                              10.0                   0.4680               16.8                   0.2340
----------------------------------------------------------------------------------------------------------------
II.L                               1.0                   0.0234                4.2                none
----------------------------------------------------------------------------------------------------------------
Total                             26.150                 0.6026               26.734                 0.2457
----------------------------------------------------------------------------------------------------------------

    Therefore, during the first 10 years after the effective date of 
the amendments, using a 7-percent discount rate, the average annual 
cost is estimated to be $30.8 million, compared to projected average 
annual benefits of $320 million, within a range estimated between $88 
million and $1.2 billion. A comparison of costs and benefits using a 3-
percent discount rate results in annualized costs of $30.1 million and 
average annual benefits of about $716 million, within an expected range 
of $197 million to $2.6 billion.

J. Cost-Effectiveness of the Regulation

    We evaluated the cost-effectiveness of the final regulation using 
the cost per incidence of cancer avoided due to lower exposure over the 
10-year evaluation period. The annual numbers of future-avoided cancers 
due to reduced radiation doses are compared to the present values of 
the costs for the evaluation period. We used projections of the annual 
number of cancer cases that would be avoided due to the final 
regulation. The cases that would be avoided because of exposure 
reductions during the first year (as improved systems are installed) 
are assumed to present themselves after a 10-year latency period. We 
expect the overall exposure reduction attributable to this final 
regulation to increase by 10 percent each year as currently installed 
x-ray systems are replaced by systems meeting the new performance 
standards. The most likely estimate for reductions in the number of 
premature cancers resulting from reduced unnecessary exposures during 
the first compliant year is 66 fewer incidents of cancer. By the 10th 
year, the exposure reductions are expected to preclude 664 annual 
cancers according to the modal dose-response relationship. Table 5 of 
this document shows the annual decrease in cancer incidence expected 
for the modal relationship, as well as for the low and high range of 
estimated reductions.

    Table 5.--Expected Annual Reductions in Cancer Incidences by Year
                    (Modal, Low, and High Estimates)
------------------------------------------------------------------------
                                           Low Range        High Range
   Compliance Year     Modal  Estimate      Estimate         Estimate
------------------------------------------------------------------------
1                      66               18               241
------------------------------------------------------------------------
2                      133              37               482
------------------------------------------------------------------------
3                      199              55               722
------------------------------------------------------------------------
4                      266              73               963
------------------------------------------------------------------------
5                      332              92               1,204
------------------------------------------------------------------------
6                      399              110              1,445
------------------------------------------------------------------------
7                      465              128              1,686
------------------------------------------------------------------------
8                      532              147              1,926
------------------------------------------------------------------------
9                      598              165              2,167
------------------------------------------------------------------------
10                     664              183              2,408
------------------------------------------------------------------------

    Although the reductions in cancers would continue beyond the 
evaluation period, we have analyzed only through the 10th year.
    While the dose reduction attributable to the final regulation 
during the first year is expected to avoid 66 future cancers, those 
cancers have an assumed latency of 10 years and would not be discovered 
until the 11th year. Therefore, while reduced exposures during year 1 
are expected to avoid 66 cancers, those avoided cancers would not have 
occurred until year 11. Each year's expected number of future avoided 
cancers is discounted to arrive at an equivalent number of avoided 
cancers during the first year. The present equivalent number of annual 
cancers avoided are estimated using both 7- and 3-percent annual 
discount rates. These equivalent numbers are shown in table 6 of this 
document.

         Table 6.--Expected Equivalent Number of Cancers Avoided Discounted to Year 1 Due to Regulation
----------------------------------------------------------------------------------------------------------------
    Annual Discount Rate            Modal Estimate               Low Estimate                High Estimate
----------------------------------------------------------------------------------------------------------------
3 Percent                                          2,217                         612                       8,034
----------------------------------------------------------------------------------------------------------------
7 Percent                                          1,173                         324                       4,252
----------------------------------------------------------------------------------------------------------------


[[Page 34025]]

    The present value of the regulatory costs, when divided by the 
equivalent number of avoided cancers, will result in the expected cost 
per cancer avoided. Annualized costs using a 3-percent discount rate 
equaled $30.1 million and result in a present value of $256.8 million 
for the evaluation period. Using a 7-percent annual discount rate, 
annualized costs of $30.8 million result in a present value of $216.3 
million. The cost per avoided cancer is shown in table 7 of this 
document.

            Table 7.--Regulatory Cost-Effectiveness per Incidence of Cancer Avoided Due to Regulation
----------------------------------------------------------------------------------------------------------------
    Annual Discount Rate            Modal Estimate               Low Estimate                High Estimate
----------------------------------------------------------------------------------------------------------------
3 Percent                                       $115,800                    $419,600                     $32,000
----------------------------------------------------------------------------------------------------------------
7 Percent                                       $184,400                    $667,600                     $50,900
----------------------------------------------------------------------------------------------------------------

    The cost-effectiveness of the final regulation using a 7-percent 
discount rate has a modal value of $184,400 within an estimated range 
of between $50,900 and $667,600 per cancer avoided. If a 3-percent 
annual discount rate is used, the regulation will cost an estimated 
$115,800 per avoided cancer within an estimated range of $32,000 to 
$419,600.

K. Small Business Impacts

    FDA believes that it is likely that the rule will have a 
significant impact on a substantial number of small entities and has 
conducted an IRFA. This analysis was designed to assess the impact of 
the rule on small entities and alert any impacted entities of the 
expected impact.
1. Description of Impact
    The objective of the regulation is to reduce the likelihood of 
adverse events due to unnecessary exposure to radiation during 
diagnostic x-ray procedures, primarily fluoroscopic procedures. The 
amendments will accomplish this by requiring performance features on 
all fluoroscopic x-ray systems that will protect patients and 
healthcare personnel while maintaining image quality.
    Manufacturers of diagnostic x-ray systems, including fluoroscopy 
equipment, are grouped within the North American Industry 
Classification System (NAICS) industry code 334517 (Irradiation 
Apparatus Manufacturers)\1\. The Small Business Administration (SBA) 
classifies as ``small'' any entity with 500 or fewer employees within 
this industry. Relatively small numbers of employees typify firms 
within this NAICS code group. About one-half of the establishments 
within this industry employ fewer than 20 workers, and companies have 
an average of 1.2 establishments per company. The manufacturers are 
relatively specialized, with about 84 percent of company sales coming 
from within the affected industry. In addition, 97 percent of all 
shipments of irradiation equipment originate by manufacturers 
classified within this industry.
---------------------------------------------------------------------------

    \1\ NAICS has replaced the Standard Industrial Classification 
(SIC) codes. NAICS Industry Group 334517 (Irradiation Apparatus) 
coincides with SIC Group 3844 (X-Ray Apparatus and Tubing).
---------------------------------------------------------------------------

    The Manufacturing Industry Series report on Irradiation Apparatus 
Manufacturing for NAICS code 334517 from the 1997 Economic Census 
indicates 136 companies having 154 establishments for this industry in 
the United States. This report also indicates that only 15 of these 
establishments have 250 or more employees, with only 5 establishments 
having more than 500 employees. Therefore, this industry sector is 
predominately composed of firms meeting the SBA description of a 
``small entity.'' Of the total value of shipments of $3,797,837,000 for 
this industry, 73 percent are from the 15 establishments with 250 or 
more employees. Thus, for the purposes of the IRFA, most of the 
diagnostic x-ray equipment manufacturing firms that will be affected by 
these amendments are small entities.
    The impact of the amendments will be similar on manufacturers of 
diagnostic x-ray systems, whether or not they are small entities. This 
impact is the increased costs to design and manufacture x-ray systems 
that meet the new requirements. For those manufacturers that produce 
smaller numbers of systems per year, the impact of the cost of system 
redesign to meet the new requirements will result in a greater per unit 
cost impact than for manufacturers with a high volume of unit sales 
over which the development costs may be spread. This may have a 
disproportionate impact on the very small firms with a low volume of 
sales.
    FDA considered whether there were approaches that could be taken to 
mitigate this impact on the firms producing the smaller numbers of 
systems. FDA, however, identified no feasible way to do this and also 
accomplish the needed public health protection. The radiation safety-
related requirements are appropriate for any x-ray system, independent 
of the circumstances of the manufacturer. FDA considers it appropriate 
for any firm producing x-ray systems to provide the level of radiation 
protection that will be afforded by the revised standard. Patients 
receiving x-ray examinations or procedures warrant the same degree of 
radiation safety regardless of the circumstances of the manufacturer of 
the equipment.
2. Analysis of Alternatives
    FDA examined and rejected several alternatives to proposing 
amendments to the performance standard. One alternative was to take no 
actions to modify the standard. This option was rejected because it 
would not permit clarification of the manner in which the standard 
should be applied to the technological changes occurring with 
fluoroscopic x-ray system design and function. This option was also 
rejected as failing to meet the public expectation that the federal 
performance standard assures adequate radiation-safety performance and 
features for radiographic and fluoroscopic x-ray systems. The changes 
that have occurred since the standard was developed in the early 1970s 
necessitate modification of the standard to reflect current technology 
and to recognize the increased radiation hazards posed by new 
fluoroscopic techniques and procedures.
    The alternative of no action to amend the performance standard was 
also rejected because that alternative would continue the current 
situation in which the U.S. standard has some performance requirements 
that differ from those in several of the standards established by the 
IEC for diagnostic x-ray systems. Several IEC radiation-safety 
performance requirements are slightly more stringent than those of the 
U.S. standard, which has not, to date, reflected a number of changes in 
x-ray system technology recognized by the IEC standards. The proposed 
amendments will harmonize the U.S. performance standard with several of

[[Page 34026]]

the requirements of the IEC standards where differences currently 
exist. Such harmonization will reduce the necessity for manufacturers 
to comply with different requirements for products marketed in the 
United States versus internationally where the IEC standards are used. 
The no-action alternative would continue these discrepancies between 
the U.S. and IEC standards.
    FDA considered various alternatives for each amendment that would 
require new equipment features or, potentially, system redesign. The 
assessment of the cost of each proposed amendment (listed in the first 
column of table 4 of this document) included consideration of 
alternatives to the specific amendment (Ref. 5). For amendments 
requiring equipment changes, consideration was given to the following 
factors: (1) The options or choices for specific limits or tolerances 
when such are imposed; (2) whether the amendment requirement should be 
limited to certain types of equipment or applied to all types of 
radiographic or fluoroscopic systems; (3) the need, where possible, to 
align the U.S. standard with the IEC standards and remove conflicts 
among the standards; and (4) whether the requirement could contribute 
to improved, safer use of the equipment. FDA concluded that the 
amendments are needed to obtain the radiation dose-reduction features 
necessary to facilitate safer use of fluoroscopy.
    One alternative considered would be to implement only certain of 
the proposed amendments and omit others, as a way of reducing the 
overall costs of the amendments. FDA rejected this approach as 
inappropriate for two reasons. First, it would not result in the 
desired harmonization between the U.S. and international standards, one 
of the main goals of these amendments. Furthermore, implementing only a 
portion of the separate amendments would not result in the anticipated 
public health benefits that will result from providing users with the 
full range of additional system-performance information and dose-
reduction features.
    In the notice of proposed rulemaking (67 FR 76056, December 10, 
2002) FDA requested comments on alternatives to these amendments that 
would accomplish the needed public health protection and, in 
particular, any alternatives that could mitigate the impact on small 
businesses. No responses to this request were received.
    A portion of the unnecessary radiation exposure resulting from 
current fluoroscopic practices might be addressed through the 
establishment of controls on the qualifications and training of 
physicians permitted to use fluoroscopic systems. Contrary to the 
current situation, such requirements could help assure that all 
physicians using fluoroscopy were adequately trained regarding 
radiation-safety practices, proper fluoroscopic system use, and methods 
for maintaining patient doses as low as reasonably achievable. Under 
current law FDA does not have the authority to establish such 
requirements. To be effective, such a program would have to be 
established by States or medical professional societies or 
certification bodies. While recognizing that encouragement of such 
activities by FDA is worthwhile, reliance on such encouragement alone 
will not result in the needed performance improvement of fluoroscopic 
x-ray systems.
3. Ensuring Small Entity Participation in Rulemaking
    FDA believes it is possible that the new regulations could have a 
significant impact on small entities. The impact will occur due to 
increased design and production costs for fluoroscopy systems. FDA 
solicited comment on the nature of this impact and whether there are 
reasonable alternatives that might accomplish the intended public 
health goals.
    The proposed regulations were available on the Internet at http://www.fda.gov for review by all interested parties. FDA communicated the 
proposed regulatory changes to the x-ray equipment manufacturers' 
organization as well as to parties that had previously indicated an 
interest in amendments to the diagnostic x-ray equipment performance 
standard. The proposed amendments were also brought to the attention of 
relevant medical professional societies and organizations whose members 
are likely to use fluoroscopic x-ray systems.

L. Reporting Requirements and Duplicate Rules

    FDA has concluded that the rule imposes new reporting and other 
compliance requirements on small businesses. In addition, FDA has 
identified no relevant Federal rules that may duplicate, overlap, or 
conflict with the rule.

M. Conclusion of the Analysis of Impacts

    FDA has examined the impacts of the amendments to the performance 
standard. Based on this evaluation, an upper-bound estimate has been 
made for average annualized costs amounting to $30.8 million, of which 
$30.4 million will be borne by the manufacturers of this equipment. FDA 
believes that the reductions in acute and long-term radiation injuries 
to patients that will be facilitated by the amendments will appreciably 
outweigh the upper-bound costs estimated for compliance with the rules. 
Finally, FDA has concluded that it is likely that this proposal will 
have a significant impact on a substantial number of small entities. 
FDA solicited comment on all aspects of this analysis and all 
assumptions used. As noted previously in this document, only two 
comments were received that directly addressed the analyses and these 
suggested, qualitatively, that FDA had underestimated either the amount 
of dose reduction that will result or the benefit of such dose 
reduction. These comments, however, do not provide a basis for revising 
the estimates of costs and benefits.

VIII. Federalism

    This final rule has been reviewed under Executive Order 13132, 
Federalism. This Executive order requires that agencies issuing 
regulations that have federalism implications follow certain 
fundamental federalism principles and provide a federalism impact 
statement that: (1) Demonstrates the agency consulted with appropriate 
State and local officials before developing the final rule, (2) 
summarizes State concerns, (3) provides the agency's position 
supporting the need for regulation, and (4) describes the extent to 
which the concerns of State and local officials have been met. 
Regulations have federalism implications whenever they have a 
substantial direct effect on the States, on the relationship between 
the National Government and the States, or on the distribution of power 
and responsibilities among various levels of government.
    The Executive order indicates that, where National standards are 
required by Federal statutes, agencies shall consult with appropriate 
State and local officials in developing those standards. It also 
directs agencies to consult with State and local officials, to the 
extent practicable and permitted by law, before issuing any regulation 
with federalism implications that preempts State law.
    In enacting the provisions of the RCHSA (which were later 
transferred from the PHS Act to the act by the SMDA), Congress 
recognized that separate State standards alone were insufficient to 
achieve the type of consistent and comprehensive protection that was 
needed. For this reason, Congress established a National radiation 
control program and

[[Page 34027]]

authorized FDA (by delegation of authority from the Secretary of the 
Department of Health and Human Services) to develop and administer 
Federal performance standards for radiation-emitting electronic 
products to more effectively protect the public health and safety (21 
U.S.C. 360hh-360ss). To ensure that State standards would not be 
inconsistent with Federal performance standards for electronic 
products, Congress included explicit preemption language in the act. 
Section 542 of the act states the following:
    Whenever any standard prescribed pursuant to section 534 with 
respect to an aspect of performance of an electronic product is in 
effect, no State or political subdivision of a State shall have any 
authority either to establish, or to continue in effect, any 
standard which is applicable to the same aspect of performance of 
such product and which is not identical to the Federal standard. 
Nothing in this subchapter shall be construed to prevent the Federal 
Government or the government of any State or political subdivision 
thereof from establishing a requirement with respect to emission of 
radiation from electronic products procured for its own use if such 
requirement imposes a more restrictive standard than that required 
to comply with the otherwise applicable Federal standard (21 U.S.C. 
360ss).
    Although States may not establish a performance standard for an 
aspect of performance of an electronic product that is not identical to 
the Federal standard, State and local governments do have authority to 
regulate the use of radiation-emitting electronic products, including 
diagnostic x-ray systems. Under this division of responsibility, the 
Federal performance standards assure that electronic products 
introduced into commerce possess the necessary radiation safety 
features. State and local governments, in turn, may prescribe who will 
be permitted to purchase or use such products. They may also establish 
requirements for facilities using these products in order to assure the 
safe function and operation of the products over their useful life. 
This division of authority and responsibility has ensured the safe use 
of diagnostic x-ray systems since the Federal performance standard was 
established in 1972.
    FDA has reached out to the States and actively sought their input 
throughout the entire process of developing this rule. In December 
1997, FDA issued an ANPRM and invited interested parties to express 
opinions regarding the need for amendments to the existing performance 
standard for diagnostic x-ray products. With the assistance of the 
Conference of Radiation Control Program Directors (CRCPD), a 
professional association whose membership includes the directors of 
State radiation control agencies, the ANPRM was brought to the 
attention of all of the State agencies responsible for radiation 
control. In response to the ANPRM, FDA received 12 comments, including 
comments from three States, one local radiation control agency, and 
comments from the CRCPD. In addition, beginning as early as April 1997, 
FDA provided opportunities for comment and discussion about the 
development of this rule at public meetings of FDA's TEPRSSC committee. 
In fact, the TEPRSSC's membership during this period included 
representatives of several State or local radiation control programs. 
Information regarding the proposed amendments was also posted on the 
agency's Internet Web site, and FDA informed the CRCPD of these 
postings.
    The States also had several opportunities to participate in the 
development of this final rule during various CRCPD meetings at which 
FDA representatives were in attendance. These meetings include: The May 
1998 and April 2001 National meetings, during which FDA made 
presentations; the May 2000 National meeting, which provided an 
opportunity for discussion about the amendments during the a special 
interest session at that meeting; and the May 2004 National meeting, 
during which FDA provided an update on the amendments. FDA also 
discussed the proposed amendments at two FDA regional meetings with 
State radiation control officials held in July and August of 2002.
    Finally, the States had an additional opportunity to participate in 
the rulemaking process by submitting comments on the proposed rule. FDA 
specifically directed a mailing of the proposed rule to State health 
officials in order to encourage them to submit comments.
    We received no comments from State or local officials regarding the 
federalism section of the proposed rule. The two states that commented 
on the proposed rule were generally supportive of the rule. The 
comments from these States have already been addressed previously in 
section III of this document. (See comments 1, 34, and 47.)
    FDA believes that this final rule is consistent with the federalism 
principles expressed in Executive Order 13132. The rule only preempts 
State law to the extent required by statute and only on the limited 
aspects of performance of fluoroscopic and radiographic x-ray systems 
covered by this rule. In addition, FDA is not aware of any existing 
State or local requirements that will be displaced by this rule. The 
purpose of this final rule is to amend the Federal performance standard 
to account for changes in technology and use of fluoroscopic and 
radiographic x-ray systems. FDA believes these amendments are vital to 
ensuring the kind of consistent and effective radiation control 
protection Congress envisioned when it enacted the radiation control 
provisions of the act.

IX. References

    The following references have been placed on public display in the 
Division of Dockets Management (see the fourth paragraph of section 
VII.A of this document) and may be seen by interested persons between 9 
a.m. and 4 p.m., Monday through Friday. (FDA has verified the Web site 
addresses, but FDA is not responsible for any subsequent changes to the 
Web sites after this document publishes in the Federal Register.)
    1. International Standard, International Electrotechnical 
Commission (IEC) 60601-2-43, ``Medical Electrical Equipment--Part 2-
43: Particular Requirements for the Safety of X-Ray Equipment for 
Interventional Procedures,'' edition 1, 2000.
    2. International Standard, International Electrotechnical 
Commission (IEC) 60601-1-3, ``Medical Electrical Equipment--Part 1: 
General Requirements for Safety. 3. Collateral Standard: General 
Requirements for Radiation Protection in Diagnostic X-Ray 
Equipment,'' 1994.
    3. International Standard, International Electrotechnical 
Commission (IEC) 60601-2-7, ``Medical Electrical Equipment-Part 2-7: 
Particular Requirements for the Safety of High-Voltage Generators of 
Diagnostic X-Ray Generators,'' 2d edition, 1998.
    4. International Standard, International Electrotechnical 
Commission (IEC) 60580, ``Medical Electrical Equipment-Dose Area 
Product Meters,'' 2d edition, 2000.
    5. ``Assessment of the Impact of the Proposed Amendments to the 
Performance Standard for Diagnostic X-Ray Equipment Addressing 
Fluoroscopic X-Ray Systems,'' Food and Drug Administration, pp. 1-
28. Also available at http://www.fda.gov/cdrh/radhealth/fluoro/amendxrad.pdf, November 15, 2000.
    6. National Council on Radiation Protection and Measurements, 
``Evaluation of the Linear-Nonthreshold Dose-Response Model for 
Ionizing Radiation,'' NCRP Report 136, Bethesda, MD, June 2001.
    7. Upton, A.C. et al., ``Health Effects of Exposure to Low 
Levels of Ionizing Radiation: BEIR V,'' Committee on the Biological 
Effects of Ionizing Radiations, Board on Radiation Effects Research, 
Commission on Life Sciences, National Research Council, National 
Academy of Science, National Academy Press, Washington, DC, 1990.
    8. Rosenstein, M. et al., Committee on Interagency Radiation 
Research and Policy

[[Page 34028]]

Coordination Science Panel Report No. 9, ``Use of BIER V and UNSCEAR 
1988 in Radiation Risk Assessment, Lifetime Total Cancer Mortality 
Risk Estimates at Low Doses and Low Dose Rates for Low-LET 
Radiation,'' (ORAU 92/F-64), OSTP, EOP, Washington, DC, December 
1992.
    9. Stern, S.H. et al., ``Estimated Benefits of Proposed 
Amendments to the FDA Radiation-Safety Standard for Diagnostic X-Ray 
Equipment.'' (Poster presented at the 2001 FDA Science Forum, 
Washington, DC, February 15-16, 2001.) Also available at http://www.fda.gov/cdrh/radhlth/021501_xray.html.
    10. Suleiman, O.H. et al., ``Nationwide Survey of Fluoroscopy: 
Radiation Dose and Image Quality,'' Radiology, vol. 203, pp. 471-
476, 1997.
    11. Proceedings of the ACR/FDA Workshop on Fluoroscopy, 
``Strategies for Improvement in Performance, Radiation Safety and 
Control,'' Dulles Hyatt Hotel, Washington, DC, October 16 and 17, 
1992, American College of Radiology, Merrifield, VA, 1993.
    12. Gagne, R.M., P.W. Quinn, and R.J. Jennings, ``Comparison of 
Beam-Hardening and K-Edge Filters for Imaging Barium and Iodine 
During Fluoroscopy,'' Medical Physics, vol. 21, pp. 107-121, 1994.
    13. Zuur, C. and F. Mettler, ``Radiological Protection and 
Safety in Medicine,'' Annals of the ICRP, ICRP Publication 73, vol. 
26, No. 2, Pergamon Press, Oxford, UK, 1996.
    14. ``Sources and Effects of Ionizing Radiation,'' United 
Nations Scientific Committee on the Effects of Atomic Radiation, 
UNSCEAR 2000 Report to the General Assembly, with Scientific 
Annexes, New York: United Nations, 2000.
    15. Rogers A.T. et al., ``The Use of a Dose-Area Product Network 
to Facilitate the Establishment of Dose Reference Levels,'' European 
Radiation Protection, Education and Training (ERPET), ERPET Course 
for Medical Physicists on Establishment of Reference Levels in 
Diagnostic Radiology, Passau, Germany, September 13-15, 1999, 
Proceedings, EC Directorate General Science, Research and 
Development Doc. RTD/0034/20, (BfS-ISH, Oberscheissheim, July 2000), 
pp. 255-260.
    16. Shrimpton, P.C. et al., A National Survey of Doses to 
Patients Undergoing a Selection of Routine X-Ray Examinations in 
English Hospitals, NRPB-R200, National Radiological Protection 
Board, Chilton, UK, September 1986.
    17. Hart, D. et al., Doses to Patients from Medical X-Ray 
Examinations in the UK--1995 Review, NRPB-R289, National 
Radiological Protection Board, Chilton, UK, July 1996.
    18. Kaczmarek, R., Nationwide Evaluation of X-Ray Trends Summary 
of 1996 Fluoroscopy Survey, (unpublished draft, November 2000).
    19. Laitano, R.F. et al., Energy Distributions and Air Kerma 
Rates of ISO and BIPM Reference Filtered X-Radiations, Comitato 
Nazionale per la Ricerca e per lo Sviluppo dell'Energia Nucleare e 
delle Energie Alternative, p. 29, December 1990.
    20. Suleiman, O.H., Development of a Method to Calculate Organ 
Doses for the Upper Gastrointestinal Fluoroscopic Examination, Ph.D. 
dissertation, Johns Hopkins University School of Hygiene and Public 
Health, Baltimore, MD, 1989.
    21. Rosenstein, M. et al., Handbook of Selected Tissue Doses for 
the Upper Gastrointestinal Fluoroscopic Examination, HHS Publication 
FDA 92-8282, U.S. Department of Health and Human Services, Public 
Health Service, Food and Drug Administration, Center for Devices and 
Radiological Health, Rockville, MD, June 1992.
    22. Geleijns, J. et al., ``A Comparison of Patient Dose for 
Examinations of the Upper Gastrointestinal Tract at 11 Conventional 
and Digital Units in The Netherlands,'' The British Journal of 
Radiology, vol. 71, pp. 745-753, July 1998.
    23. Stern, S.H. et al., Handbook of Selected Tissue Doses for 
Fluoroscopic and Cineangiographic Examination of the Coronary 
Arteries (in SI Units), HHS Publication FDA 95-8289, U.S. Department 
of Health and Human Services, Public Health Service, Food and Drug 
Administration, Center for Devices and Radiological Health, 
Rockville, MD, September 1995.
    24. Nationwide Inpatient Sample Release 6 for 1997, compiled by 
HCUPnet, Healthcare Cost and Utilization Project, Agency for 
Healthcare Research and Quality, Rockville, MD, http://www.ahrq.gov/data/hcup/, August 2000.
    25. Peterson, E.D. et al., ``Evolving Trends in Interventional 
Device Use and Outcomes: Results from the National Cardiovascular 
Network Database,'' American Heart Journal, vol. 139, no. 2, pp. 
198-207, February 2000.
    26. Viscusi, K., Fatal Tradeoffs: Public and Private 
Responsibilities for Risk, Oxford University Press, 1992.
    27. Fisher, A. et al., ``The Value of Reducing Risks of Death: A 
Note on New Evidence,'' The Journal of Policy Analysis and 
Management, vol. 8, no. 1, pp. 88-100, 1989.
    28. Mudarri, D., Costs and Benefits of Smoking Restrictions: An 
Assessment of the Smoke-Free Environment Act of 1993, Environmental 
Protection Agency, 1994.
    29. U.S. National Cancer Institute, Surveillance, Epidemiology, 
and End Results (SEER) Cancer Statistics Review (1973-1994), Annual, 
pp. 123-143, 1997.
    30. Legoretta, A. et al., ``Cost of Breast Cancer Treatment,'' 
Archives of Internal Medicine, vol. 156, pp. 2197-2201, 1996.
    31. Brown, M. and L. Fintor, ``The Economic Burden of Cancer,'' 
Cancer Prevention and Control, edited by P. Greenwald et al., Marcel 
Dekker Inc., 1995.
    32. Kaplan, R. et al., ``Health Status: Types of Validity and 
the Index of Well-Being,'' Health Service Research, winter issue, 
pp. 478-507, 1976.
    33. Radloff, L., ``The CES-D Scale: A Self-Report Depression 
Scale for Research in the General Population,'' The Journal of 
Applied Psychological Measurement, vol. 1, no. 3, pp. 385-401, 1977.
    34. Shrout, P., ``Scaling of Stressful Life Events,'' Stressful 
Life Events and Their Contexts, ed. by B.S. Dowrenwend and B.P. 
Dowenrend, Rutgers University Press, 1984.
    35. Chen, M. et al., ``Social Indicators for Health Planning and 
Policy Analysis,'' Policy Sciences, vol. 6, pp. 71-89, 1975.
    36. U.S. National Center for Health Statistics, Expectation of 
Life and Expected Death by Race, Sex, and Age, Vital Statistics of 
the United States, 1995.
    37. U.S. Consumer Product Safety Commission, Estimating the Cost 
to Society of Consumer Product Injuries, CPSC-C-95-1164, National 
Public Services Research Institute, January 1998.
    38. Kaplan, R. and J. Bush, ``Health-Related Quality of Life 
Measurement for Evaluation Research and Policy Analysis,'' Health 
Psychology, vol. 1, no. 1, pp. 61-80, 1982.

List of Subjects in 21 CFR Part 1020

    Electronic products, Medical devices, Radiation protection, 
Reporting and recordkeeping requirements, Television, X-rays.

0
Therefore, under the Federal Food, Drug, and Cosmetic Act, and under 
authority delegated to the Commissioner of Food and Drugs, 21 CFR part 
1020 is amended as follows:

PART 1020--PERFORMANCE STANDARDS FOR IONIZING RADIATION EMITTING 
PRODUCTS

0
1. The authority citation for 21 CFR part 1020 continues to read as 
follows:

    Authority: 21 U.S.C. 351, 352, 360e-360j, 360gg-360ss, 371, 381.

0
2. Revise Sec.  1020.30 to read as follows:


Sec.  1020.30  Diagnostic x-ray systems and their major components.

    (a) Applicability. (1) The provisions of this section are 
applicable to:
    (i) The following components of diagnostic x-ray systems:
    (A) Tube housing assemblies, x-ray controls, x-ray high-voltage 
generators, x-ray tables, cradles, film changers, vertical cassette 
holders mounted in a fixed location and cassette holders with front 
panels, and beam-limiting devices manufactured after August 1, 1974.
    (B) Fluoroscopic imaging assemblies manufactured after August 1, 
1974, and before April 26, 1977, or after June 10, 2006.
    (C) Spot-film devices and image intensifiers manufactured after 
April 26, 1977.
    (D) Cephalometric devices manufactured after February 25, 1978.
    (E) Image receptor support devices for mammographic x-ray systems 
manufactured after September 5, 1978.
    (F) Image receptors that are electrically powered or connected with 
the x-ray system manufactured on or after June 10, 2006.
    (G) Fluoroscopic air kerma display devices manufactured on or after 
June 10, 2006.
    (ii) Diagnostic x-ray systems, except computed tomography x-ray 
systems, incorporating one or more of such

[[Page 34029]]

components; however, such x-ray systems shall be required to comply 
only with those provisions of this section and Sec. Sec.  1020.31 and 
1020.32, which relate to the components certified in accordance with 
paragraph (c) of this section and installed into the systems.
    (iii) Computed tomography (CT) x-ray systems manufactured before 
November 29, 1984.
    (iv) CT gantries manufactured after September 3, 1985.
    (2) The following provisions of this section and Sec.  1020.33 are 
applicable to CT x-ray systems manufactured or remanufactured on or 
after November 29, 1984:
    (i) Section 1020.30(a);
    (ii) Section 1020.30(b) ``Technique factors'';
    (iii) Section 1020.30(b) ``CT,'' ``Dose,'' ``Scan,'' ``Scan time,'' 
and ``Tomogram'';
    (iv) Section 1020.30(h)(3)(vi) through (h)(3)(viii);
    (v) Section 1020.30(n);
    (vi) Section 1020.33(a) and (b);
    (vii) Section 1020.33(c)(1) as it affects Sec.  1020.33(c)(2); and
    (viii) Section 1020.33(c)(2).
    (3) The provisions of this section and Sec.  1020.33 in its 
entirety, including those provisions in paragraph (a)(2) of this 
section, are applicable to CT x-ray systems manufactured or 
remanufactured on or after September 3, 1985. The date of manufacture 
of the CT system is the date of manufacture of the CT gantry.
    (b) Definitions. As used in this section and Sec. Sec.  1020.31, 
1020.32, and 1020.33, the following definitions apply:
    Accessible surface means the external surface of the enclosure or 
housing provided by the manufacturer.
    Accessory component means:
    (1) A component used with diagnostic x-ray systems, such as a 
cradle or film changer, that is not necessary for the compliance of the 
system with applicable provisions of this subchapter but which requires 
an initial determination of compatibility with the system; or
    (2) A component necessary for compliance of the system with 
applicable provisions of this subchapter but which may be interchanged 
with similar compatible components without affecting the system's 
compliance, such as one of a set of interchangeable beam-limiting 
devices; or
    (3) A component compatible with all x-ray systems with which it may 
be used and that does not require compatibility or installation 
instructions, such as a tabletop cassette holder.
    Air kerma means kerma in air (see definition of Kerma).
    Air kerma rate (AKR) means the air kerma per unit time.
    Aluminum equivalent means the thickness of aluminum (type 1100 
alloy)\1\ affording the same attenuation, under specified conditions, 
as the material in question.
---------------------------------------------------------------------------

    \1\ The nominal chemical composition of type 1100 aluminum alloy 
is 99.00 percent minimum aluminum, 0.12 percent copper, as given in 
``Aluminum Standards and Data'' (1969). Copies may be obtained from 
The Aluminum Association, New York, NY.
---------------------------------------------------------------------------

    Articulated joint means a joint between two separate sections of a 
tabletop which joint provides the capacity for one of the sections to 
pivot on the line segment along which the sections join.
    Assembler means any person engaged in the business of assembling, 
replacing, or installing one or more components into a diagnostic x-ray 
system or subsystem. The term includes the owner of an x-ray system or 
his or her employee or agent who assembles components into an x-ray 
system that is subsequently used to provide professional or commercial 
services.
    Attenuation block means a block or stack of type 1100 aluminum 
alloy, or aluminum alloy having equivalent attenuation, with dimensions 
20 centimeters (cm) or larger by 20 cm or larger by 3.8 cm, that is 
large enough to intercept the entire x-ray beam.
    Automatic exposure control (AEC) means a device which automatically 
controls one or more technique factors in order to obtain at a 
preselected location(s) a required quantity of radiation.
    Automatic exposure rate control (AERC) means a device which 
automatically controls one or more technique factors in order to obtain 
at a preselected location(s) a required quantity of radiation per unit 
time.
    Beam axis means a line from the source through the centers of the 
x-ray fields.
    Beam-limiting device means a device which provides a means to 
restrict the dimensions of the x-ray field.
    C-arm fluoroscope means a fluoroscopic x-ray system in which the 
image receptor and the x-ray tube housing assembly are connected or 
coordinated to maintain a spatial relationship. Such a system allows a 
change in the direction of the beam axis with respect to the patient 
without moving the patient.
    Cantilevered tabletop means a tabletop designed such that the 
unsupported portion can be extended at least 100 cm beyond the support.
    Cassette holder means a device, other than a spot-film device, that 
supports and/or fixes the position of an x-ray film cassette during an 
x-ray exposure.
    Cephalometric device means a device intended for the radiographic 
visualization and measurement of the dimensions of the human head.
    Coefficient of variation means the ratio of the standard deviation 
to the mean value of a population of observations. It is estimated 
using the following equation:
[GRAPHIC] [TIFF OMITTED] TR10JN05.001


where:
s = Estimated standard deviation of the population.
X = Mean value of observations in sample.
Xi = ith observation sampled.
n = Number of observations sampled.
    Computed tomography (CT) means the production of a tomogram by the 
acquisition and computer processing of x-ray transmission data.
    Control panel means that part of the x-ray control upon which are 
mounted the switches, knobs, pushbuttons, and other hardware necessary 
for manually setting the technique factors.
    Cooling curve means the graphical relationship between heat units 
stored and cooling time.
    Cradle means:
    (1) A removable device which supports and may restrain a patient 
above an x-ray table; or

[[Page 34030]]

    (2) A device;
    (i) Whose patient support structure is interposed between the 
patient and the image receptor during normal use;
    (ii) Which is equipped with means for patient restraint; and
    (iii) Which is capable of rotation about its long (longitudinal) 
axis.
    CT gantry means tube housing assemblies, beam-limiting devices, 
detectors, and the supporting structures, frames, and covers which hold 
and/or enclose these components.
    Cumulative air kerma means the total air kerma accrued from the 
beginning of an examination or procedure and includes all contributions 
from fluoroscopic and radiographic irradiation.
    Diagnostic source assembly means the tube housing assembly with a 
beam-limiting device attached.
    Diagnostic x-ray system means an x-ray system designed for 
irradiation of any part of the human body for the purpose of diagnosis 
or visualization.
    Dose means the absorbed dose as defined by the International 
Commission on Radiation Units and Measurements. The absorbed dose, D, 
is the quotient of de by dm, where de is the mean energy imparted to 
matter of mass dm; thus D=de/dm, in units of J/kg, where the special 
name for the unit of absorbed dose is gray (Gy).
    Equipment means x-ray equipment.
    Exposure (X) means the quotient of dQ by dm where dQ is the 
absolute value of the total charge of the ions of one sign produced in 
air when all the electrons and positrons liberated or created by 
photons in air of mass dm are completely stopped in air; thus X=dQ/dm, 
in units of C/kg. A second meaning of exposure is the process or 
condition during which the x-ray tube produces x-ray radiation.
    Field emission equipment means equipment which uses an x-ray tube 
in which electron emission from the cathode is due solely to action of 
an electric field.
    Fluoroscopic air kerma display device means a device, subsystem, or 
component that provides the display of AKR and cumulative air kerma 
required by Sec.  1020.32(k). It includes radiation detectors, if any, 
electronic and computer components, associated software, and data 
displays.
    Fluoroscopic imaging assembly means a subsystem in which x-ray 
photons produce a set of fluoroscopic images or radiographic images 
recorded from the fluoroscopic image receptor. It includes the image 
receptor(s), electrical interlocks, if any, and structural material 
providing linkage between the image receptor and diagnostic source 
assembly.
    Fluoroscopic irradiation time means the cumulative duration during 
an examination or procedure of operator-applied continuous pressure to 
the device, enabling x-ray tube activation in any fluoroscopic mode of 
operation.
    Fluoroscopy means a technique for generating x-ray images and 
presenting them simultaneously and continuously as visible images. This 
term has the same meaning as the term ``radioscopy'' in the standards 
of the International Electrotechnical Commission.
    General purpose radiographic x-ray system means any radiographic x-
ray system which, by design, is not limited to radiographic examination 
of specific anatomical regions.
    Half-value layer (HVL) means the thickness of specified material 
which attenuates the beam of radiation to an extent such that the AKR 
is reduced to one-half of its original value. In this definition the 
contribution of all scattered radiation, other than any which might be 
present initially in the beam concerned, is deemed to be excluded.
    Image intensifier means a device, installed in its housing, which 
instantaneously converts an x-ray pattern into a corresponding light 
image of higher energy density.
    Image receptor means any device, such as a fluorescent screen, 
radiographic film, x-ray image intensifier tube, solid-state detector, 
or gaseous detector, which transforms incident x-ray photons either 
into a visible image or into another form which can be made into a 
visible image by further transformations. In those cases where means 
are provided to preselect a portion of the image receptor, the term 
``image receptor'' shall mean the preselected portion of the device.
    Image receptor support device means, for mammography x-ray systems, 
that part of the system designed to support the image receptor during a 
mammographic examination and to provide a primary protective barrier.
    Isocenter means the center of the smallest sphere through which the 
beam axis passes when the equipment moves through a full range of 
rotations about its common center.
    Kerma means the quantity as defined by the International Commission 
on Radiation Units and Measurements. The kerma, K, is the quotient of 
dEtr by dm, where dEtr is the sum of the initial 
kinetic energies of all the charged particles liberated by uncharged 
particles in a mass dm of material; thus K=dEtr/dm, in units 
of J/kg, where the special name for the unit of kerma is gray (Gy). 
When the material is air, the quantity is referred to as ``air kerma.''
    Last-image-hold (LIH) radiograph means an image obtained either by 
retaining one or more fluoroscopic images, which may be temporally 
integrated, at the end of a fluoroscopic exposure or by initiating a 
separate and distinct radiographic exposure automatically and 
immediately in conjunction with termination of the fluoroscopic 
exposure.
    Lateral fluoroscope means the x-ray tube and image receptor 
combination in a biplane system dedicated to the lateral projection. It 
consists of the lateral x-ray tube housing assembly and the lateral 
image receptor that are fixed in position relative to the table with 
the x-ray beam axis parallel to the plane of the table.
    Leakage radiation means radiation emanating from the diagnostic 
source assembly except for:
    (1) The useful beam; and
    (2) Radiation produced when the exposure switch or timer is not 
activated.
    Leakage technique factors means the technique factors associated 
with the diagnostic source assembly which are used in measuring leakage 
radiation. They are defined as follows:
    (1) For diagnostic source assemblies intended for capacitor energy 
storage equipment, the maximum-rated peak tube potential and the 
maximum-rated number of exposures in an hour for operation at the 
maximum-rated peak tube potential with the quantity of charge per 
exposure being 10 millicoulombs (or 10 mAs) or the minimum obtainable 
from the unit, whichever is larger;
    (2) For diagnostic source assemblies intended for field emission 
equipment rated for pulsed operation, the maximum-rated peak tube 
potential and the maximum-rated number of x-ray pulses in an hour for 
operation at the maximum-rated peak tube potential; and
    (3) For all other diagnostic source assemblies, the maximum-rated 
peak tube potential and the maximum-rated continuous tube current for 
the maximum-rated peak tube potential.
    Light field means that area of the intersection of the light beam 
from the beam-limiting device and one of the set of planes parallel to 
and including the plane of the image receptor, whose perimeter is the 
locus of points at which the illuminance is one-fourth of the maximum 
in the intersection.
    Line-voltage regulation means the difference between the no-load 
and the load line potentials expressed as a

[[Page 34031]]

percent of the load line potential; that is,
Percent line-voltage regulation = 100(Vn - 
Vi)/Vi
where:
Vn = No-load line potential and
Vi = Load line potential.
    Maximum line current means the root mean square current in the 
supply line of an x-ray machine operating at its maximum rating.
    Mode of operation means, for fluoroscopic systems, a distinct 
method of fluoroscopy or radiography provided by the manufacturer and 
selected with a set of several technique factors or other control 
settings uniquely associated with the mode. The set of distinct 
technique factors and control settings for the mode may be selected by 
the operation of a single control. Examples of distinct modes of 
operation include normal fluoroscopy (analog or digital), high-level 
control fluoroscopy, cineradiography (analog or digital), digital 
subtraction angiography, electronic radiography using the fluoroscopic 
image receptor, and photospot recording. In a specific mode of 
operation, certain system variables affecting air kerma, AKR, or image 
quality, such as image magnification, x-ray field size, pulse rate, 
pulse duration, number of pulses, source-image receptor distance (SID), 
or optical aperture, may be adjustable or may vary; their variation per 
se does not comprise a mode of operation different from the one that 
has been selected.
    Movable tabletop means a tabletop which, when assembled for use, is 
capable of movement with respect to its supporting structure within the 
plane of the tabletop.
    Non-image-intensified fluoroscopy means fluoroscopy using only a 
fluorescent screen.
    Peak tube potential means the maximum value of the potential 
difference across the x-ray tube during an exposure.
    Primary protective barrier means the material, excluding filters, 
placed in the useful beam to reduce the radiation exposure for 
protection purposes.
    Pulsed mode means operation of the x-ray system such that the x-ray 
tube current is pulsed by the x-ray control to produce one or more 
exposure intervals of duration less than one-half second.
    Quick change x-ray tube means an x-ray tube designed for use in its 
associated tube housing such that:
    (1) The tube cannot be inserted in its housing in a manner that 
would result in noncompliance of the system with the requirements of 
paragraphs (k) and (m) of this section;
    (2) The focal spot position will not cause noncompliance with the 
provisions of this section or Sec.  1020.31 or 1020.32;
    (3) The shielding within the tube housing cannot be displaced; and
    (4) Any removal and subsequent replacement of a beam-limiting 
device during reloading of the tube in the tube housing will not result 
in noncompliance of the x-ray system with the applicable field 
limitation and alignment requirements of Sec. Sec.  1020.31 and 
1020.32.
    Radiation therapy simulation system means a radiographic or 
fluoroscopic x-ray system intended for localizing the volume to be 
exposed during radiation therapy and confirming the position and size 
of the therapeutic irradiation field.
    Radiography means a technique for generating and recording an x-ray 
pattern for the purpose of providing the user with an image(s) after 
termination of the exposure.
    Rated line voltage means the range of potentials, in volts, of the 
supply line specified by the manufacturer at which the x-ray machine is 
designed to operate.
    Rated output current means the maximum allowable load current of 
the x-ray high-voltage generator.
    Rated output voltage means the allowable peak potential, in volts, 
at the output terminals of the x-ray high-voltage generator.
    Rating means the operating limits specified by the manufacturer.
    Recording means producing a retrievable form of an image resulting 
from x-ray photons.
    Scan means the complete process of collecting x-ray transmission 
data for the production of a tomogram. Data may be collected 
simultaneously during a single scan for the production of one or more 
tomograms.
    Scan time means the period of time between the beginning and end of 
x-ray transmission data accumulation for a single scan.
    Solid state x-ray imaging device means an assembly, typically in a 
rectangular panel configuration, that intercepts x-ray photons and 
converts the photon energy into a modulated electronic signal 
representative of the x-ray intensity over the area of the imaging 
device. The electronic signal is then used to create an image for 
display and/or storage.
    Source means the focal spot of the x-ray tube.
    Source-image receptor distance (SID) means the distance from the 
source to the center of the input surface of the image receptor.
    Source-skin distance (SSD) means the distance from the source to 
the center of the entrant x-ray field in the plane tangent to the 
patient skin surface.
    Spot-film device means a device intended to transport and/or 
position a radiographic image receptor between the x-ray source and 
fluoroscopic image receptor. It includes a device intended to hold a 
cassette over the input end of the fluoroscopic image receptor for the 
purpose of producing a radiograph.
    Stationary tabletop means a tabletop which, when assembled for use, 
is incapable of movement with respect to its supporting structure 
within the plane of the tabletop.
    Technique factors means the following conditions of operation:
    (1) For capacitor energy storage equipment, peak tube potential in 
kilovolts (kV) and quantity of charge in milliampere-seconds (mAs);
    (2) For field emission equipment rated for pulsed operation, peak 
tube potential in kV and number of x-ray pulses;
    (3) For CT equipment designed for pulsed operation, peak tube 
potential in kV, scan time in seconds, and either tube current in 
milliamperes (mA), x-ray pulse width in seconds, and the number of x-
ray pulses per scan, or the product of the tube current, x-ray pulse 
width, and the number of x-ray pulses in mAs;
    (4) For CT equipment not designed for pulsed operation, peak tube 
potential in kV, and either tube current in mA and scan time in 
seconds, or the product of tube current and exposure time in mAs and 
the scan time when the scan time and exposure time are equivalent; and
    (5) For all other equipment, peak tube potential in kV, and either 
tube current in mA and exposure time in seconds, or the product of tube 
current and exposure time in mAs.
    Tomogram means the depiction of the x-ray attenuation properties of 
a section through a body.
    Tube means an x-ray tube, unless otherwise specified.
    Tube housing assembly means the tube housing with tube installed. 
It includes high-voltage and/or filament transformers and other 
appropriate elements when they are contained within the tube housing.
    Tube rating chart means the set of curves which specify the rated 
limits of operation of the tube in terms of the technique factors.
    Useful beam means the radiation which passes through the tube 
housing port and the aperture of the beam-limiting device when the 
exposure switch or timer is activated.
    Variable-aperture beam-limiting device means a beam-limiting device 
which has the capacity for stepless

[[Page 34032]]

adjustment of the x-ray field size at a given SID.
    Visible area means the portion of the input surface of the image 
receptor over which incident x-ray photons are producing a visible 
image.
    X-ray control means a device which controls input power to the x-
ray high-voltage generator and/or the x-ray tube. It includes equipment 
such as timers, phototimers, automatic brightness stabilizers, and 
similar devices, which control the technique factors of an x-ray 
exposure.
    X-ray equipment means an x-ray system, subsystem, or component 
thereof. Types of x-ray equipment are as follows:
    (1) Mobile x-ray equipment means x-ray equipment mounted on a 
permanent base with wheels and/or casters for moving while completely 
assembled;
    (2) Portable x-ray equipment means x-ray equipment designed to be 
hand-carried; and
    (3) Stationary x-ray equipment means x-ray equipment which is 
installed in a fixed location.
    X-ray field means that area of the intersection of the useful beam 
and any one of the set of planes parallel to and including the plane of 
the image receptor, whose perimeter is the locus of points at which the 
AKR is one-fourth of the maximum in the intersection.
    X-ray high-voltage generator means a device which transforms 
electrical energy from the potential supplied by the x-ray control to 
the tube operating potential. The device may also include means for 
transforming alternating current to direct current, filament 
transformers for the x-ray tube(s), high-voltage switches, electrical 
protective devices, and other appropriate elements.
    X-ray subsystem means any combination of two or more components of 
an x-ray system for which there are requirements specified in this 
section and Sec. Sec.  1020.31 and 1020.32.
    X-ray system means an assemblage of components for the controlled 
production of x-rays. It includes minimally an x-ray high-voltage 
generator, an x-ray control, a tube housing assembly, a beam-limiting 
device, and the necessary supporting structures. Additional components 
which function with the system are considered integral parts of the 
system.
    X-ray table means a patient support device with its patient support 
structure (tabletop) interposed between the patient and the image 
receptor during radiography and/or fluoroscopy. This includes, but is 
not limited to, any stretcher equipped with a radiolucent panel and any 
table equipped with a cassette tray (or bucky), cassette tunnel, 
fluoroscopic image receptor, or spot-film device beneath the tabletop.
    X-ray tube means any electron tube which is designed for the 
conversion of electrical energy into x-ray energy.
    (c) Manufacturers' responsibility. Manufacturers of products 
subject to Sec. Sec.  1020.30 through 1020.33 shall certify that each 
of their products meet all applicable requirements when installed into 
a diagnostic x-ray system according to instructions. This certification 
shall be made under the format specified in Sec.  1010.2 of this 
chapter. Manufacturers may certify a combination of two or more 
components if they obtain prior authorization in writing from the 
Director of the Office of Compliance of the Center for Devices and 
Radiological Health (CDRH). Manufacturers shall not be held responsible 
for noncompliance of their products if that noncompliance is due solely 
to the improper installation or assembly of that product by another 
person; however, manufacturers are responsible for providing assembly 
instructions adequate to assure compliance of their components with the 
applicable provisions of Sec. Sec.  1020.30 through 1020.33.
    (d) Assemblers' responsibility. An assembler who installs one or 
more components certified as required by paragraph (c) of this section 
shall install certified components that are of the type required by 
Sec.  1020.31, 1020.32, or 1020.33 and shall assemble, install, adjust, 
and test the certified components according to the instructions of 
their respective manufacturers. Assemblers shall not be liable for 
noncompliance of a certified component if the assembly of that 
component was according to the component manufacturer's instruction.
    (1) Reports of assembly. All assemblers who install certified 
components shall file a report of assembly, except as specified in 
paragraph (d)(2) of this section. The report will be construed as the 
assembler's certification and identification under Sec. Sec.  1010.2 
and 1010.3 of this chapter. The assembler shall affirm in the report 
that the manufacturer's instructions were followed in the assembly or 
that the certified components as assembled into the system meet all 
applicable requirements of Sec. Sec.  1020.30 through 1020.33. All 
assembler reports must be on a form prescribed by the Director, CDRH. 
Completed reports must be submitted to the Director, the purchaser, 
and, where applicable, to the State agency responsible for radiation 
protection within 15 days following completion of the assembly.
    (2) Exceptions to reporting requirements. Reports of assembly need 
not be submitted for any of the following:
    (i) Reloaded or replacement tube housing assemblies that are 
reinstalled in or newly assembled into an existing x-ray system;
    (ii) Certified accessory components that have been identified as 
such to CDRH in the report required under Sec.  1002.10 of this 
chapter;
    (iii) Repaired components, whether or not removed from the system 
and reinstalled during the course of repair, provided the original 
installation into the system was reported; or
    (iv)(A) Components installed temporarily in an x-ray system in 
place of components removed temporarily for repair, provided the 
temporarily installed component is identified by a tag or label bearing 
the following information:
Temporarily Installed Component
This certified component has been assembled, installed, adjusted, 
and tested by me according to the instructions provided by the 
manufacturer.
Signature
Company Name
Street Address, P.O. Box
City, State, Zip Code
Date of Installation
    (B) The replacement of the temporarily installed component by a 
component other than the component originally removed for repair shall 
be reported as specified in paragraph (d)(1) of this section.
    (e) Identification of x-ray components. In addition to the 
identification requirements specified in Sec.  1010.3 of this chapter, 
manufacturers of components subject to this section and Sec. Sec.  
1020.31, 1020.32, and 1020.33, except high-voltage generators contained 
within tube housings and beam-limiting devices that are integral parts 
of tube housings, shall permanently inscribe or affix thereon the model 
number and serial number of the product so that they are legible and 
accessible to view. The word ``model'' or ``type'' shall appear as part 
of the manufacturer's required identification of certified x-ray 
components. Where the certification of a system or subsystem, 
consisting of two or more components, has been authorized under 
paragraph (c) of this section, a single inscription, tag, or label 
bearing the model number and serial number may be used to identify the 
product.
    (1) Tube housing assemblies. In a similar manner, manufacturers of 
tube housing assemblies shall also inscribe or affix thereon the name 
of the manufacturer, model number, and serial

[[Page 34033]]

number of the x-ray tube which the tube housing assembly incorporates.
    (2) Replacement of tubes. Except as specified in paragraph (e)(3) 
of this section, the replacement of an x-ray tube in a previously 
manufactured tube housing assembly certified under paragraph (c) of 
this section constitutes manufacture of a new tube housing assembly, 
and the manufacturer is subject to the provisions of paragraph (e)(1) 
of this section. The manufacturer shall remove, cover, or deface any 
previously affixed inscriptions, tags, or labels that are no longer 
applicable.
    (3) Quick-change x-ray tubes. The requirements of paragraph (e)(2) 
of this section shall not apply to tube housing assemblies designed and 
designated by their original manufacturer to contain quick change x-ray 
tubes. The manufacturer of quick-change x-ray tubes shall include with 
each replacement tube a label with the tube manufacturer's name, the 
model, and serial number of the x-ray tube. The manufacturer of the 
tube shall instruct the assembler who installs the new tube to attach 
the label to the tube housing assembly and to remove, cover, or deface 
the previously affixed inscriptions, tags, or labels that are described 
by the tube manufacturer as no longer applicable.
    (f) [Reserved]
    (g) Information to be provided to assemblers. Manufacturers of 
components listed in paragraph (a)(1) of this section shall provide to 
assemblers subject to paragraph (d) of this section and, upon request, 
to others at a cost not to exceed the cost of publication and 
distribution, instructions for assembly, installation, adjustment, and 
testing of such components adequate to assure that the products will 
comply with applicable provisions of this section and Sec. Sec.  
1020.31, 1020.32, and 1020.33, when assembled, installed, adjusted, and 
tested as directed. Such instructions shall include specifications of 
other components compatible with that to be installed when compliance 
of the system or subsystem depends on their compatibility. Such 
specifications may describe pertinent physical characteristics of the 
components and/or may list by manufacturer model number the components 
which are compatible. For x-ray controls and generators manufactured 
after May 3, 1994, manufacturers shall provide:
    (1) A statement of the rated line voltage and the range of line-
voltage regulation for operation at maximum line current;
    (2) A statement of the maximum line current of the x-ray system 
based on the maximum input voltage and current characteristics of the 
tube housing assembly compatible with rated output voltage and rated 
output current characteristics of the x-ray control and associated 
high-voltage generator. If the rated input voltage and current 
characteristics of the tube housing assembly are not known by the 
manufacturer of the x-ray control and associated high-voltage 
generator, the manufacturer shall provide information necessary to 
allow the assembler to determine the maximum line current for the 
particular tube housing assembly(ies);
    (3) A statement of the technique factors that constitute the 
maximum line current condition described in paragraph (g)(2) of this 
section.
    (h) Information to be provided to users. Manufacturers of x-ray 
equipment shall provide to purchasers and, upon request, to others at a 
cost not to exceed the cost of publication and distribution, manuals or 
instruction sheets which shall include the following technical and 
safety information:
    (1) All x-ray equipment. For x-ray equipment to which this section 
and Sec. Sec.  1020.31, 1020.32, and 1020.33 are applicable, there 
shall be provided:
    (i) Adequate instructions concerning any radiological safety 
procedures and precautions which may be necessary because of unique 
features of the equipment; and
    (ii) A schedule of the maintenance necessary to keep the equipment 
in compliance with this section and Sec. Sec.  1020.31, 1020.32, and 
1020.33.
    (2) Tube housing assemblies. For each tube housing assembly, there 
shall be provided:
    (i) Statements of the leakage technique factors for all 
combinations of tube housing assemblies and beam-limiting devices for 
which the tube housing assembly manufacturer states compatibility, the 
minimum filtration permanently in the useful beam expressed as 
millimeters (mm) of aluminum equivalent, and the peak tube potential at 
which the aluminum equivalent was obtained;
    (ii) Cooling curves for the anode and tube housing; and
    (iii) Tube rating charts. If the tube is designed to operate from 
different types of x-ray high-voltage generators (such as single-phase 
self rectified, single-phase half-wave rectified, single-phase full-
wave rectified, 3-phase 6-pulse, 3-phase 12-pulse, constant potential, 
capacitor energy storage) or under modes of operation such as alternate 
focal spot sizes or speeds of anode rotation which affect its rating, 
specific identification of the difference in ratings shall be noted.
    (3) X-ray controls and generators. For the x-ray control and 
associated x-ray high-voltage generator, there shall be provided:
    (i) A statement of the rated line voltage and the range of line-
voltage regulation for operation at maximum line current;
    (ii) A statement of the maximum line current of the x-ray system 
based on the maximum input voltage and output current characteristics 
of the tube housing assembly compatible with rated output voltage and 
rated current characteristics of the x-ray control and associated high-
voltage generator. If the rated input voltage and current 
characteristics of the tube housing assembly are not known by the 
manufacturer of the x-ray control and associated high-voltage 
generator, the manufacturer shall provide necessary information to 
allow the purchaser to determine the maximum line current for his 
particular tube housing assembly(ies);
    (iii) A statement of the technique factors that constitute the 
maximum line current condition described in paragraph (h)(3)(ii) of 
this section;
    (iv) In the case of battery-powered generators, a specification of 
the minimum state of charge necessary for proper operation;
    (v) Generator rating and duty cycle;
    (vi) A statement of the maximum deviation from the preindication 
given by labeled technique factor control settings or indicators during 
any radiographic or CT exposure where the equipment is connected to a 
power supply as described in accordance with this paragraph. In the 
case of fixed technique factors, the maximum deviation from the nominal 
fixed value of each factor shall be stated;
    (vii) A statement of the maximum deviation from the continuous 
indication of x-ray tube potential and current during any fluoroscopic 
exposure when the equipment is connected to a power supply as described 
in accordance with this paragraph; and
    (viii) A statement describing the measurement criteria for all 
technique factors used in paragraphs (h)(3)(iii), (h)(3)(vi), and 
(h)(3)(vii) of this section; for example, the beginning and endpoints 
of exposure time measured with respect to a certain percentage of the 
voltage waveform.
    (4) Beam-limiting device. For each variable-aperture beam-limiting 
device, there shall be provided;
    (i) Leakage technique factors for all combinations of tube housing 
assemblies and beam-limiting devices

[[Page 34034]]

for which the beam-limiting device manufacturer states compatibility; 
and
    (ii) A statement including the minimum aluminum equivalent of that 
part of the device through which the useful beam passes and including 
the x-ray tube potential at which the aluminum equivalent was obtained. 
When two or more filters are provided as part of the device, the 
statement shall include the aluminum equivalent of each filter.
    (5) Imaging system information. For x-ray systems manufactured on 
or after June 10, 2006, that produce images using the fluoroscopic 
image receptor, the following information shall be provided in a 
separate, single section of the user's instruction manual or in a 
separate manual devoted to this information:
    (i) For each mode of operation, a description of the mode and 
detailed instructions on how the mode is engaged and disengaged. The 
description of the mode shall identify those technique factors and 
system controls that are fixed or automatically adjusted by selection 
of the mode of operation, including the manner in which the automatic 
adjustment is controlled. This information shall include how the 
operator can recognize which mode of operation has been selected prior 
to initiation of x-ray production.
    (ii) For each mode of operation, a descriptive example(s) of any 
specific clinical procedure(s) or imaging task(s) for which the mode is 
recommended or designed and how each mode should be used. Such 
recommendations do not preclude other clinical uses.
    (6) Displays of values of AKR and cumulative air kerma. For 
fluoroscopic x-ray systems manufactured on or after June 10, 2006, the 
following shall be provided:
    (i) A schedule of maintenance for any system instrumentation 
associated with the display of air kerma information necessary to 
maintain the displays of AKR and cumulative air kerma within the limits 
of allowed uncertainty specified by Sec.  1020.32(k)(6) and, if the 
capability for user calibration of the display is provided, adequate 
instructions for such calibration;
    (ii) Identification of the distances along the beam axis:
    (A) From the focal spot to the isocenter, and
    (B) From the focal spot to the reference location to which 
displayed values of AKR and cumulative air kerma refer according to 
Sec.  1020.32(k)(4);
    (iii) A rationale for specification of a reference irradiation 
location alternative to 15 cm from the isocenter toward the x-ray 
source along the beam axis when such alternative specification is made 
according to Sec.  1020.32(k)(4)(ii).
    (i) [Reserved]
    (j) Warning label. The control panel containing the main power 
switch shall bear the warning statement, legible and accessible to 
view:
    ``Warning: This x-ray unit may be dangerous to patient and 
operator unless safe exposure factors, operating instructions and 
maintenance schedules are observed.''
    (k) Leakage radiation from the diagnostic source assembly. The 
leakage radiation from the diagnostic source assembly measured at a 
distance of 1 meter in any direction from the source shall not exceed 
0.88 milligray (mGy) air kerma (vice 100 milliroentgen (mR) exposure) 
in 1 hour when the x-ray tube is operated at the leakage technique 
factors. If the maximum rated peak tube potential of the tube housing 
assembly is greater than the maximum rated peak tube potential for the 
diagnostic source assembly, positive means shall be provided to limit 
the maximum x-ray tube potential to that of the diagnostic source 
assembly. Compliance shall be determined by measurements averaged over 
an area of 100 square cm with no linear dimension greater than 20 cm.
    (l) Radiation from components other than the diagnostic source 
assembly. The radiation emitted by a component other than the 
diagnostic source assembly shall not exceed an air kerma of 18 microGy 
(vice 2 mR exposure) in 1 hour at 5 cm from any accessible surface of 
the component when it is operated in an assembled x-ray system under 
any conditions for which it was designed. Compliance shall be 
determined by measurements averaged over an area of 100 square cm with 
no linear dimension greater than 20 cm.
    (m) Beam quality--(1) Half-value layer (HVL). The HVL of the useful 
beam for a given x-ray tube potential shall not be less than the 
appropriate value shown in table 1 in paragraph (m)(1) of this section 
under the heading ``Specified Dental Systems,'' for any dental x-ray 
system designed for use with intraoral image receptors and manufactured 
after December 1, 1980; under the heading ``I--Other X-Ray Systems,'' 
for any dental x-ray system designed for use with intraoral image 
receptors and manufactured before December 1, 1980, and all other x-ray 
systems subject to this section and manufactured before June 10, 2006; 
and under the heading ``II--Other X-Ray Systems,'' for all x-ray 
systems, except dental x-ray systems designed for use with intraoral 
image receptors, subject to this section and manufactured on or after 
June 10, 2006. If it is necessary to determine such HVL at an x-ray 
tube potential which is not listed in table 1 in paragraph (m)(1) of 
this section, linear interpolation or extrapolation may be made. 
Positive means\2\ shall be provided to ensure that at least the minimum 
filtration needed to achieve the above beam quality requirements is in 
the useful beam during each exposure. Table 1 follows:
---------------------------------------------------------------------------

    \2\ In the case of a system, which is to be operated with more 
than one thickness of filtration, this requirement can be met by a 
filter interlocked with the kilovoltage selector which will prevent 
x-ray emissions if the minimum required filtration is not in place.

                                                                        Table 1.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                    X-Ray Tube Voltage (kilovolt peak)                                              Minimum HVL (mm of aluminum)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                    Measured Operating           Specified Dental          I--Other X-Ray           II--Other X-Ray
           Designed Operating Range                     Potential                   Systems\1\               Systems\2\                Systems\3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Below 51                                                   30                           1.5                      0.3                       0.3
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                           40                           1.5                      0.4                       0.4
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                           50                           1.5                      0.5                       0.5
--------------------------------------------------------------------------------------------------------------------------------------------------------
51 to 70                                                   51                           1.5                      1.2                       1.3
--------------------------------------------------------------------------------------------------------------------------------------------------------

[[Page 34035]]

 
                                                           60                           1.5                      1.3                       1.5
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                           70                           1.5                      1.5                       1.8
--------------------------------------------------------------------------------------------------------------------------------------------------------
Above 70                                                   71                           2.1                      2.1                       2.5
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                           80                           2.3                      2.3                       2.9
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                           90                           2.5                      2.5                       3.2
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          100                           2.7                      2.7                       3.6
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          110                           3.0                      3.0                       3.9
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          120                           3.2                      3.2                       4.3
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          130                           3.5                      3.5                       4.7
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          140                           3.8                      3.8                       5.0
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          150                           4.1                      4.1                       5.4
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Dental x-ray systems designed for use with intraoral image receptors and manufactured after December 1, 1980.
\2\ Dental x-ray systems designed for use with intraoral image receptors and manufactured before or on December 1, 1980, and all other x-ray systems
  subject to this section and manufactured before June 10, 2006.
\3\ All x-ray systems, except dental x-ray systems designed for use with intraoral image receptors, subject to this section and manufactured on or after
  June 10, 2006.

    (2) Optional filtration. Fluoroscopic systems manufactured on or 
after June 10, 2006, incorporating an x-ray tube(s) with a continuous 
output of 1 kilowatt or more and an anode heat storage capacity of 1 
million heat units or more shall provide the option of adding x-ray 
filtration to the diagnostic source assembly in addition to the amount 
needed to meet the HVL provisions of Sec.  1020.30(m)(1). The selection 
of this additional x-ray filtration shall be either at the option of 
the user or automatic as part of the selected mode of operation. A 
means of indicating which combination of additional filtration is in 
the x-ray beam shall be provided.
    (3) Measuring compliance. For capacitor energy storage equipment, 
compliance shall be determined with the maximum selectable quantity of 
charge per exposure.
    (n) Aluminum equivalent of material between patient and image 
receptor. Except when used in a CT x-ray system, the aluminum 
equivalent of each of the items listed in table 2 in paragraph (n) of 
this section, which are used between the patient and image receptor, 
may not exceed the indicated limits. Compliance shall be determined by 
x-ray measurements made at a potential of 100 kilovolts peak and with 
an x-ray beam that has an HVL specified in table 1 in paragraph (m)(1) 
of this section for the potential. This requirement applies to front 
panel(s) of cassette holders and film changers provided by the 
manufacturer for patient support or for prevention of foreign object 
intrusions. It does not apply to screens and their associated 
mechanical support panels or grids. Table 2 follows:

                                Table 2.
------------------------------------------------------------------------
                                                        Maximum Aluminum
                         Item                              Equivalent
                                                         (millimeters)
------------------------------------------------------------------------
1. Front panel(s) of cassette holders (total of all)                1.2
------------------------------------------------------------------------
2. Front panel(s) of film changer (total of all)                    1.2
------------------------------------------------------------------------
3. Cradle                                                           2.3
------------------------------------------------------------------------
4. Tabletop, stationary, without articulated joints                 1.2
------------------------------------------------------------------------
5. Tabletop, movable, without articulated joint(s)                  1.7
 (including stationary subtop)
------------------------------------------------------------------------
6. Tabletop, with radiolucent panel having one                      1.7
 articulated joint
------------------------------------------------------------------------
7. Tabletop, with radiolucent panel having two or                   2.3
 more articulated joints
------------------------------------------------------------------------
8. Tabletop, cantilevered                                           2.3
------------------------------------------------------------------------
9. Tabletop, radiation therapy simulator                            5.0
------------------------------------------------------------------------


[[Page 34036]]

    (o) Battery charge indicator. On battery-powered generators, visual 
means shall be provided on the control panel to indicate whether the 
battery is in a state of charge adequate for proper operation.
    (p) [Reserved]
    (q) Modification of certified diagnostic x-ray components and 
systems. (1) Diagnostic x-ray components and systems certified in 
accordance with Sec.  1010.2 of this chapter shall not be modified such 
that the component or system fails to comply with any applicable 
provision of this chapter unless a variance in accordance with Sec.  
1010.4 of this chapter or an exemption under section 534(a)(5) or 
538(b) of the Federal Food, Drug, and Cosmetic Act has been granted.
    (2) The owner of a diagnostic x-ray system who uses the system in a 
professional or commercial capacity may modify the system, provided the 
modification does not result in the failure of the system or component 
to comply with the applicable requirements of this section or of Sec.  
1020.31, 1020.32, or 1020.33. The owner who causes such modification 
need not submit the reports required by subpart B of part 1002 of this 
chapter, provided the owner records the date and the details of the 
modification in the system records and maintains this information, and 
provided the modification of the x-ray system does not result in a 
failure to comply with Sec.  1020.31, 1020.32, or 1020.33.

0
3. Revise Sec.  1020.31 to read as follows:


Sec.  1020.31  Radiographic equipment.

    The provisions of this section apply to equipment for radiography, 
except equipment for fluoroscopic imaging or for recording images from 
the fluoroscopic image receptor, or computed tomography x-ray systems 
manufactured on or after November 29, 1984.
    (a) Control and indication of technique factors--(1) Visual 
indication. The technique factors to be used during an exposure shall 
be indicated before the exposure begins, except when automatic exposure 
controls are used, in which case the technique factors which are set 
prior to the exposure shall be indicated. On equipment having fixed 
technique factors, this requirement may be met by permanent markings. 
Indication of technique factors shall be visible from the operator's 
position except in the case of spot films made by the fluoroscopist.
    (2) Timers. Means shall be provided to terminate the exposure at a 
preset time interval, a preset product of current and time, a preset 
number of pulses, or a preset radiation exposure to the image receptor.
    (i) Except during serial radiography, the operator shall be able to 
terminate the exposure at any time during an exposure of greater than 
one-half second. Except during panoramic dental radiography, 
termination of exposure shall cause automatic resetting of the timer to 
its initial setting or to zero. It shall not be possible to make an 
exposure when the timer is set to a zero or off position if either 
position is provided.
    (ii) During serial radiography, the operator shall be able to 
terminate the x-ray exposure(s) at any time, but means may be provided 
to permit completion of any single exposure of the series in process.
    (3) Automatic exposure controls. When an automatic exposure control 
is provided:
    (i) Indication shall be made on the control panel when this mode of 
operation is selected;
    (ii) When the x-ray tube potential is equal to or greater than 51 
kilovolts peak (kVp), the minimum exposure time for field emission 
equipment rated for pulsed operation shall be equal to or less than a 
time interval equivalent to two pulses and the minimum exposure time 
for all other equipment shall be equal to or less than 1/60 second or a 
time interval required to deliver 5 milliampere-seconds (mAs), 
whichever is greater;
    (iii) Either the product of peak x-ray tube potential, current, and 
exposure time shall be limited to not more than 60 kilowatt-seconds 
(kWs) per exposure or the product of x-ray tube current and exposure 
time shall be limited to not more than 600 mAs per exposure, except 
when the x-ray tube potential is less than 51 kVp, in which case the 
product of x-ray tube current and exposure time shall be limited to not 
more than 2,000 mAs per exposure; and
    (iv) A visible signal shall indicate when an exposure has been 
terminated at the limits described in paragraph (a)(3)(iii) of this 
section, and manual resetting shall be required before further 
automatically timed exposures can be made.
    (4) Accuracy. Deviation of technique factors from indicated values 
shall not exceed the limits given in the information provided in 
accordance with Sec.  1020.30(h)(3).
    (b) Reproducibility. The following requirements shall apply when 
the equipment is operated on an adequate power supply as specified by 
the manufacturer in accordance with the requirements of Sec.  
1020.30(h)(3):
    (1) Coefficient of variation. For any specific combination of 
selected technique factors, the estimated coefficient of variation of 
the air kerma shall be no greater than 0.05.
    (2) Measuring compliance. Determination of compliance shall be 
based on 10 consecutive measurements taken within a time period of 1 
hour. Equipment manufactured after September 5, 1978, shall be subject 
to the additional requirement that all variable controls for technique 
factors shall be adjusted to alternate settings and reset to the test 
setting after each measurement. The percent line-voltage regulation 
shall be determined for each measurement. All values for percent line-
voltage regulation shall be within 1 of the mean value for 
all measurements. For equipment having automatic exposure controls, 
compliance shall be determined with a sufficient thickness of 
attenuating material in the useful beam such that the technique factors 
can be adjusted to provide individual exposures of a minimum of 12 
pulses on field emission equipment rated for pulsed operation or no 
less than one-tenth second per exposure on all other equipment.
    (c) Linearity. The following requirements apply when the equipment 
is operated on a power supply as specified by the manufacturer in 
accordance with the requirements of Sec.  1020.30(h)(3) for any fixed 
x-ray tube potential within the range of 40 percent to 100 percent of 
the maximum rated.
    (1) Equipment having independent selection of x-ray tube current 
(mA). The average ratios of air kerma to the indicated milliampere-
seconds product (mGy/mAs) obtained at any two consecutive tube current 
settings shall not differ by more than 0.10 times their sum. This is: 
|X1 - X2| <= 0.10(X1 + X2); 
where X1 and X2 are the average mGy/mAs values 
obtained at each of two consecutive mAs selector settings or at two 
settings differing by no more than a factor of 2 where the mAs selector 
provides continuous selection.
    (2) Equipment having selection of x-ray tube current-exposure time 
product (mAs). For equipment manufactured after May 3, 1994, the 
average ratios of air kerma to the indicated milliampere-seconds 
product (mGy/mAs) obtained at any two consecutive mAs selector settings 
shall not differ by more than 0.10 times their sum. This is: 
|X1 - X2| <= 0.10 (X1 + 
X2); where X1 and X2 are the average 
mGy/mAs values obtained at each of two consecutive mAs selector 
settings or at two settings differing by no more than a factor of 2 
where the mAs selector provides continuous selection.

[[Page 34037]]

    (3) Measuring compliance. Determination of compliance will be based 
on 10 exposures, made within 1 hour, at each of the two settings. These 
two settings may include any two focal spot sizes except where one is 
equal to or less than 0.45 mm and the other is greater than 0.45 mm. 
For purposes of this requirement, focal spot size is the focal spot 
size specified by the x-ray tube manufacturer. The percent line-voltage 
regulation shall be determined for each measurement. All values for 
percent line-voltage regulation at any one combination of technique 
factors shall be within 1 of the mean value for all 
measurements at these technique factors.
    (d) Field limitation and alignment for mobile, portable, and 
stationary general purpose x-ray systems. Except when spot-film devices 
are in service, mobile, portable, and stationary general purpose 
radiographic x-ray systems shall meet the following requirements:
    (1) Variable x-ray field limitation. A means for stepless 
adjustment of the size of the x-ray field shall be provided. Each 
dimension of the minimum field size at an SID of 100 centimeters (cm) 
shall be equal to or less than 5 cm.
    (2) Visual definition. (i) Means for visually defining the 
perimeter of the x-ray field shall be provided. The total misalignment 
of the edges of the visually defined field with the respective edges of 
the x-ray field along either the length or width of the visually 
defined field shall not exceed 2 percent of the distance from the 
source to the center of the visually defined field when the surface 
upon which it appears is perpendicular to the axis of the x-ray beam.
    (ii) When a light localizer is used to define the x-ray field, it 
shall provide an average illuminance of not less than 160 lux (15 
footcandles) at 100 cm or at the maximum SID, whichever is less. The 
average illuminance shall be based on measurements made in the 
approximate center of each quadrant of the light field. Radiation 
therapy simulation systems are exempt from this requirement.
    (iii) The edge of the light field at 100 cm or at the maximum SID, 
whichever is less, shall have a contrast ratio, corrected for ambient 
lighting, of not less than 4 in the case of beam-limiting devices 
designed for use on stationary equipment, and a contrast ratio of not 
less than 3 in the case of beam-limiting devices designed for use on 
mobile and portable equipment. The contrast ratio is defined as 
I1/I2, where I1 is the illuminance 3 
mm from the edge of the light field toward the center of the field; and 
I2 is the illuminance 3 mm from the edge of the light field 
away from the center of the field. Compliance shall be determined with 
a measuring aperture of 1 mm.
    (e) Field indication and alignment on stationary general purpose x-
ray equipment. Except when spot-film devices are in service, stationary 
general purpose x-ray systems shall meet the following requirements in 
addition to those prescribed in paragraph (d) of this section:
    (1) Means shall be provided to indicate when the axis of the x-ray 
beam is perpendicular to the plane of the image receptor, to align the 
center of the x-ray field with respect to the center of the image 
receptor to within 2 percent of the SID, and to indicate the SID to 
within 2 percent;
    (2) The beam-limiting device shall numerically indicate the field 
size in the plane of the image receptor to which it is adjusted;
    (3) Indication of field size dimensions and SIDs shall be specified 
in centimeters and/or inches and shall be such that aperture 
adjustments result in x-ray field dimensions in the plane of the image 
receptor which correspond to those indicated by the beam-limiting 
device to within 2 percent of the SID when the beam axis is indicated 
to be perpendicular to the plane of the image receptor; and
    (4) Compliance measurements will be made at discrete SIDs and image 
receptor dimensions in common clinical use (such as SIDs of 100, 150, 
and 200 cm and/or 36, 40, 48, and 72 inches and nominal image receptor 
dimensions of 13, 18, 24, 30, 35, 40, and 43 cm and/or 5, 7, 8, 9, 10, 
11, 12, 14, and 17 inches) or at any other specific dimensions at which 
the beam-limiting device or its associated diagnostic x-ray system is 
uniquely designed to operate.
    (f) Field limitation on radiographic x-ray equipment other than 
general purpose radiographic systems--(1) Equipment for use with 
intraoral image receptors. Radiographic equipment designed for use with 
an intraoral image receptor shall be provided with means to limit the 
x-ray beam such that:
    (i) If the minimum source-to-skin distance (SSD) is 18 cm or more, 
the x-ray field at the minimum SSD shall be containable in a circle 
having a diameter of no more than 7 cm; and
    (ii) If the minimum SSD is less than 18 cm, the x-ray field at the 
minimum SSD shall be containable in a circle having a diameter of no 
more than 6 cm.
    (2) X-ray systems designed for one image receptor size. 
Radiographic equipment designed for only one image receptor size at a 
fixed SID shall be provided with means to limit the field at the plane 
of the image receptor to dimensions no greater than those of the image 
receptor, and to align the center of the x-ray field with the center of 
the image receptor to within 2 percent of the SID, or shall be provided 
with means to both size and align the x-ray field such that the x-ray 
field at the plane of the image receptor does not extend beyond any 
edge of the image receptor.
    (3) Systems designed for mammography--(i) Radiographic systems 
designed only for mammography and general purpose radiography systems, 
when special attachments for mammography are in service, manufactured 
on or after November 1, 1977, and before September 30, 1999, shall be 
provided with means to limit the useful beam such that the x-ray field 
at the plane of the image receptor does not extend beyond any edge of 
the image receptor at any designated SID except the edge of the image 
receptor designed to be adjacent to the chest wall where the x-ray 
field may not extend beyond this edge by more than 2 percent of the 
SID. This requirement can be met with a system that performs as 
prescribed in paragraphs (f)(4)(i), (f)(4)(ii), and (f)(4)(iii) of this 
section. When the beam-limiting device and image receptor support 
device are designed to be used to immobilize the breast during a 
mammographic procedure and the SID may vary, the SID indication 
specified in paragraphs (f)(4)(ii) and (f)(4)(iii) of this section 
shall be the maximum SID for which the beam-limiting device or aperture 
is designed.
    (ii) Mammographic beam-limiting devices manufactured on or after 
September 30, 1999, shall be provided with a means to limit the useful 
beam such that the x-ray field at the plane of the image receptor does 
not extend beyond any edge of the image receptor by more than 2 percent 
of the SID. This requirement can be met with a system that performs as 
prescribed in paragraphs (f)(4)(i), (f)(4)(ii), and (f)(4)(iii) of this 
section. For systems that allow changes in the SID, the SID indication 
specified in paragraphs (f)(4)(ii) and (f)(4)(iii) of this section 
shall be the maximum SID for which the beam-limiting device or aperture 
is designed.
    (iii) Each image receptor support device manufactured on or after 
November 1, 1977, intended for installation on a system designed for 
mammography shall have clear and permanent markings to indicate the 
maximum image receptor size for which it is designed.

[[Page 34038]]

    (4) Other x-ray systems. Radiographic systems not specifically 
covered in paragraphs (d), (e), (f)(2), (f)(3), and (h) of this section 
and systems covered in paragraph (f)(1) of this section, which are also 
designed for use with extraoral image receptors and when used with an 
extraoral image receptor, shall be provided with means to limit the x-
ray field in the plane of the image receptor so that such field does 
not exceed each dimension of the image receptor by more than 2 percent 
of the SID, when the axis of the x-ray beam is perpendicular to the 
plane of the image receptor. In addition, means shall be provided to 
align the center of the x-ray field with the center of the image 
receptor to within 2 percent of the SID, or means shall be provided to 
both size and align the x-ray field such that the x-ray field at the 
plane of the image receptor does not extend beyond any edge of the 
image receptor. These requirements may be met with:
    (i) A system which performs in accordance with paragraphs (d) and 
(e) of this section; or when alignment means are also provided, may be 
met with either;
    (ii) An assortment of removable, fixed-aperture, beam-limiting 
devices sufficient to meet the requirement for each combination of 
image receptor size and SID for which the unit is designed. Each such 
device shall have clear and permanent markings to indicate the image 
receptor size and SID for which it is designed; or
    (iii) A beam-limiting device having multiple fixed apertures 
sufficient to meet the requirement for each combination of image 
receptor size and SID for which the unit is designed. Permanent, 
clearly legible markings shall indicate the image receptor size and SID 
for which each aperture is designed and shall indicate which aperture 
is in position for use.
    (g) Positive beam limitation (PBL). The requirements of this 
paragraph shall apply to radiographic systems which contain PBL.
    (1) Field size. When a PBL system is provided, it shall prevent x-
ray production when:
    (i) Either the length or width of the x-ray field in the plane of 
the image receptor differs from the corresponding image receptor 
dimension by more than 3 percent of the SID; or
    (ii) The sum of the length and width differences as stated in 
paragraph (g)(1)(i) of this section without regard to sign exceeds 4 
percent of the SID.
    (iii) The beam limiting device is at an SID for which PBL is not 
designed for sizing.
    (2) Conditions for PBL. When provided, the PBL system shall 
function as described in paragraph (g)(1) of this section whenever all 
the following conditions are met:
    (i) The image receptor is inserted into a permanently mounted 
cassette holder;
    (ii) The image receptor length and width are less than 50 cm;
    (iii) The x-ray beam axis is within 3 degrees of 
vertical and the SID is 90 cm to 130 cm inclusive; or the x-ray beam 
axis is within 3 degrees of horizontal and the SID is 90 cm 
to 205 cm inclusive;
    (iv) The x-ray beam axis is perpendicular to the plane of the image 
receptor to within 3 degrees; and
    (v) Neither tomographic nor stereoscopic radiography is being 
performed.
    (3) Measuring compliance. Compliance with the requirements of 
paragraph (g)(1) of this section shall be determined when the equipment 
indicates that the beam axis is perpendicular to the plane of the image 
receptor and the provisions of paragraph (g)(2) of this section are 
met. Compliance shall be determined no sooner than 5 seconds after 
insertion of the image receptor.
    (4) Operator initiated undersizing. The PBL system shall be capable 
of operation such that, at the discretion of the operator, the size of 
the field may be made smaller than the size of the image receptor 
through stepless adjustment of the field size. Each dimension of the 
minimum field size at an SID of 100 cm shall be equal to or less than 5 
cm. Return to PBL function as described in paragraph (g)(1) of this 
section shall occur automatically upon any change of image receptor 
size or SID.
    (5) Override of PBL. A capability may be provided for overriding 
PBL in case of system failure and for servicing the system. This 
override may be for all SIDs and image receptor sizes. A key shall be 
required for any override capability that is accessible to the 
operator. It shall not be possible to remove the key while PBL is 
overridden. Each such key switch or key shall be clearly and durably 
labeled as follows:
For X-ray Field Limitation System Failure
The override capability is considered accessible to the operator if 
it is referenced in the operator's manual or in other material 
intended for the operator or if its location is such that the 
operator would consider it part of the operational controls.
    (h) Field limitation and alignment for spot-film devices. The 
following requirements shall apply to spot-film devices, except when 
the spot-film device is provided for use with a radiation therapy 
simulation system:
    (1) Means shall be provided between the source and the patient for 
adjustment of the x-ray field size in the plane of the image receptor 
to the size of that portion of the image receptor which has been 
selected on the spot-film selector. Such adjustment shall be 
accomplished automatically when the x-ray field size in the plane of 
the image receptor is greater than the selected portion of the image 
receptor. If the x-ray field size is less than the size of the selected 
portion of the image receptor, the field size shall not open 
automatically to the size of the selected portion of the image receptor 
unless the operator has selected that mode of operation.
    (2) Neither the length nor the width of the x-ray field in the 
plane of the image receptor shall differ from the corresponding 
dimensions of the selected portion of the image receptor by more than 3 
percent of the SID when adjusted for full coverage of the selected 
portion of the image receptor. The sum, without regard to sign, of the 
length and width differences shall not exceed 4 percent of the SID. On 
spot-film devices manufactured after February 25, 1978, if the angle 
between the plane of the image receptor and beam axis is variable, 
means shall be provided to indicate when the axis of the x-ray beam is 
perpendicular to the plane of the image receptor, and compliance shall 
be determined with the beam axis indicated to be perpendicular to the 
plane of the image receptor.
    (3) The center of the x-ray field in the plane of the image 
receptor shall be aligned with the center of the selected portion of 
the image receptor to within 2 percent of the SID.
    (4) Means shall be provided to reduce the x-ray field size in the 
plane of the image receptor to a size smaller than the selected portion 
of the image receptor such that:
    (i) For spot-film devices used on fixed-SID fluoroscopic systems 
which are not required to, and do not provide stepless adjustment of 
the x-ray field, the minimum field size, at the greatest SID, does not 
exceed 125 square cm; or
    (ii) For spot-film devices used on fluoroscopic systems that have a 
variable SID and/or stepless adjustment of the field size, the minimum 
field size, at the greatest SID, shall be containable in a square of 5 
cm by 5 cm.
    (5) A capability may be provided for overriding the automatic x-ray 
field size adjustment in case of system failure. If it is so provided, 
a signal visible at the fluoroscopist's position shall indicate 
whenever the automatic x-ray field size adjustment override is engaged. 
Each

[[Page 34039]]

such system failure override switch shall be clearly labeled as 
follows:
For X-ray Field Limitation System Failure
    (i) Source-skin distance--(1) X-ray systems designed for use with 
an intraoral image receptor shall be provided with means to limit the 
source-skin distance to not less than:
    (i) Eighteen cm if operable above 50 kVp; or
    (ii) Ten cm if not operable above 50 kVp.
    (2) Mobile and portable x-ray systems other than dental shall be 
provided with means to limit the source-skin distance to not less than 
30 cm.
    (j) Beam-on indicators. The x-ray control shall provide visual 
indication whenever x-rays are produced. In addition, a signal audible 
to the operator shall indicate that the exposure has terminated.
    (k) Multiple tubes. Where two or more radiographic tubes are 
controlled by one exposure switch, the tube or tubes which have been 
selected shall be clearly indicated before initiation of the exposure. 
This indication shall be both on the x-ray control and at or near the 
tube housing assembly which has been selected.
    (l) Radiation from capacitor energy storage equipment. Radiation 
emitted from the x-ray tube shall not exceed:
    (1) An air kerma of 0.26 microGy (vice 0.03 mR exposure) in 1 
minute at 5 cm from any accessible surface of the diagnostic source 
assembly, with the beam-limiting device fully open, the system fully 
charged, and the exposure switch, timer, or any discharge mechanism not 
activated. Compliance shall be determined by measurements averaged over 
an area of 100 square cm, with no linear dimension greater than 20 cm; 
and
    (2) An air kerma of 0.88 mGy (vice 100 mR exposure) in 1 hour at 
100 cm from the x-ray source, with the beam-limiting device fully open, 
when the system is discharged through the x-ray tube either manually or 
automatically by use of a discharge switch or deactivation of the input 
power. Compliance shall be determined by measurements of the maximum 
air kerma per discharge multiplied by the total number of discharges in 
1 hour (duty cycle). The measurements shall be averaged over an area of 
100 square cm with no linear dimension greater than 20 cm.
    (m) Primary protective barrier for mammography x-ray systems--(1) 
For x-ray systems manufactured after September 5, 1978, and before 
September 30, 1999, which are designed only for mammography, the 
transmission of the primary beam through any image receptor support 
provided with the system shall be limited such that the air kerma 5 cm 
from any accessible surface beyond the plane of the image receptor 
supporting device does not exceed 0.88 microGy (vice 0.1 mR exposure) 
for each activation of the tube.
    (2) For mammographic x-ray systems manufactured on or after 
September 30, 1999:
    (i) At any SID where exposures can be made, the image receptor 
support device shall provide a primary protective barrier that 
intercepts the cross section of the useful beam along every direction 
except at the chest wall edge.
    (ii) The x-ray system shall not permit exposure unless the 
appropriate barrier is in place to intercept the useful beam as 
required in paragraph (m)(2)(i) of this section.
    (iii) The transmission of the useful beam through the primary 
protective barrier shall be limited such that the air kerma 5 cm from 
any accessible surface beyond the plane of the primary protective 
barrier does not exceed 0.88 microGy (vice 0.1 mR exposure) for each 
activation of the tube.
    (3) Compliance with the requirements of paragraphs (m)(1) and 
(m)(2)(iii) of this section for transmission shall be determined with 
the x-ray system operated at the minimum SID for which it is designed, 
at the maximum rated peak tube potential, at the maximum rated product 
of x-ray tube current and exposure time (mAs) for the maximum rated 
peak tube potential, and by measurements averaged over an area of 100 
square cm with no linear dimension greater than 20 cm. The sensitive 
volume of the radiation measuring instrument shall not be positioned 
beyond the edge of the primary protective barrier along the chest wall 
side.

0
4. Revise Sec.  1020.32 to read as follows:


Sec.  1020.32  Fluoroscopic equipment.

    The provisions of this section apply to equipment for fluoroscopic 
imaging or for recording images from the fluoroscopic image receptor, 
except computed tomography x-ray systems manufactured on or after 
November 29, 1984.
    (a) Primary protective barrier--(1) Limitation of useful beam. The 
fluoroscopic imaging assembly shall be provided with a primary 
protective barrier which intercepts the entire cross section of the 
useful beam at any SID. The x-ray tube used for fluoroscopy shall not 
produce x-rays unless the barrier is in position to intercept the 
entire useful beam. The AKR due to transmission through the barrier 
with the attenuation block in the useful beam combined with radiation 
from the fluoroscopic image receptor shall not exceed 3.34 x 
10-3 percent of the entrance AKR, at a distance of 10 cm 
from any accessible surface of the fluoroscopic imaging assembly beyond 
the plane of the image receptor. Radiation therapy simulation systems 
shall be exempt from this requirement provided the systems are intended 
only for remote control operation and the manufacturer sets forth 
instructions for assemblers with respect to control location as part of 
the information required in Sec.  1020.30(g). Additionally, the 
manufacturer shall provide to users, under Sec.  1020.30(h)(1)(i), 
precautions concerning the importance of remote control operation.
    (2) Measuring compliance. The AKR shall be measured in accordance 
with paragraph (d) of this section. The AKR due to transmission through 
the primary barrier combined with radiation from the fluoroscopic image 
receptor shall be determined by measurements averaged over an area of 
100 square cm with no linear dimension greater than 20 cm. If the 
source is below the tabletop, the measurement shall be made with the 
input surface of the fluoroscopic imaging assembly positioned 30 cm 
above the tabletop. If the source is above the tabletop and the SID is 
variable, the measurement shall be made with the end of the beam-
limiting device or spacer as close to the tabletop as it can be placed, 
provided that it shall not be closer than 30 cm. Movable grids and 
compression devices shall be removed from the useful beam during the 
measurement. For all measurements, the attenuation block shall be 
positioned in the useful beam 10 cm from the point of measurement of 
entrance AKR and between this point and the input surface of the 
fluoroscopic imaging assembly.
    (b) Field limitation--(1) Angulation. For fluoroscopic equipment 
manufactured after February 25, 1978, when the angle between the image 
receptor and the beam axis of the x-ray beam is variable, means shall 
be provided to indicate when the axis of the x-ray beam is 
perpendicular to the plane of the image receptor. Compliance with 
paragraphs (b)(4) and (b)(5) of this section shall be determined with 
the beam axis indicated to be perpendicular to the plane of the image 
receptor.
    (2) Further means for limitation. Means shall be provided to permit 
further limitation of the x-ray field to sizes smaller than the limits 
of paragraphs (b)(4) and (b)(5). Beam-limiting devices manufactured 
after May 22, 1979, and incorporated in equipment with a variable SID 
and/or

[[Page 34040]]

the capability of a visible area of greater than 300 square cm, shall 
be provided with means for stepless adjustment of the x-ray field. 
Equipment with a fixed SID and the capability of a visible area of no 
greater than 300 square cm shall be provided with either stepless 
adjustment of the x-ray field or with a means to further limit the x-
ray field size at the plane of the image receptor to 125 square cm or 
less. Stepless adjustment shall, at the greatest SID, provide 
continuous field sizes from the maximum obtainable to a field size 
containable in a square of 5 cm by 5 cm. This paragraph does not apply 
to non-image-intensified fluoroscopy.
    (3) Non-image-intensified fluoroscopy. The x-ray field produced by 
non-image-intensified fluoroscopic equipment shall not extend beyond 
the entire visible area of the image receptor. Means shall be provided 
for stepless adjustment of field size. The minimum field size, at the 
greatest SID, shall be containable in a square of 5 cm by 5 cm.
    (4) Fluoroscopy and radiography using the fluoroscopic imaging 
assembly with inherently circular image receptors. (i) For fluoroscopic 
equipment manufactured before June 10, 2006, other than radiation 
therapy simulation systems, the following applies:
    (A) Neither the length nor the width of the x-ray field in the 
plane of the image receptor shall exceed that of the visible area of 
the image receptor by more than 3 percent of the SID. The sum of the 
excess length and the excess width shall be no greater than 4 percent 
of the SID.
    (B) For rectangular x-ray fields used with circular image 
receptors, the error in alignment shall be determined along the length 
and width dimensions of the x-ray field which pass through the center 
of the visible area of the image receptor.
    (ii) For fluoroscopic equipment manufactured on or after June 10, 
2006, other than radiation therapy simulation systems, the maximum area 
of the x-ray field in the plane of the image receptor shall conform 
with one of the following requirements:
    (A) When any linear dimension of the visible area of the image 
receptor measured through the center of the visible area is less than 
or equal to 34 cm in any direction, at least 80 percent of the area of 
the x-ray field overlaps the visible area of the image receptor, or
    (B) When any linear dimension of the visible area of the image 
receptor measured through the center of the visible area is greater 
than 34 cm in any direction, the x-ray field measured along the 
direction of greatest misalignment with the visible area of the image 
receptor does not extend beyond the edge of the visible area of the 
image receptor by more than 2 cm.
    (5) Fluoroscopy and radiography using the fluoroscopic imaging 
assembly with inherently rectangular image receptors. For x-ray systems 
manufactured on or after June 10, 2006, the following applies:
    (i) Neither the length nor the width of the x-ray field in the 
plane of the image receptor shall exceed that of the visible area of 
the image receptor by more than 3 percent of the SID. The sum of the 
excess length and the excess width shall be no greater than 4 percent 
of the SID.
    (ii) The error in alignment shall be determined along the length 
and width dimensions of the x-ray field which pass through the center 
of the visible area of the image receptor.
    (6) Override capability. If the fluoroscopic x-ray field size is 
adjusted automatically as the SID or image receptor size is changed, a 
capability may be provided for overriding the automatic adjustment in 
case of system failure. If it is so provided, a signal visible at the 
fluoroscopist's position shall indicate whenever the automatic field 
adjustment is overridden. Each such system failure override switch 
shall be clearly labeled as follows:
For X-ray Field Limitation System Failure
    (c) Activation of tube. X-ray production in the fluoroscopic mode 
shall be controlled by a device which requires continuous pressure by 
the operator for the entire time of any exposure. When recording serial 
radiographic images from the fluoroscopic image receptor, the operator 
shall be able to terminate the x-ray exposure(s) at any time, but means 
may be provided to permit completion of any single exposure of the 
series in process.
    (d) Air kerma rates. For fluoroscopic equipment, the following 
requirements apply:
    (1) Fluoroscopic equipment manufactured before May 19, 1995--(i) 
Equipment provided with automatic exposure rate control (AERC) shall 
not be operable at any combination of tube potential and current that 
will result in an AKR in excess of 88 mGy per minute (vice 10 R/min 
exposure rate) at the measurement point specified in Sec.  
1020.32(d)(3), except as specified in Sec.  1020.32(d)(1)(v).
    (ii) Equipment provided without AERC shall not be operable at any 
combination of tube potential and current that will result in an AKR in 
excess of 44 mGy per minute (vice 5 R/min exposure rate) at the 
measurement point specified in Sec.  1020.32(d)(3), except as specified 
in Sec.  1020.32(d)(1)(v).
    (iii) Equipment provided with both an AERC mode and a manual mode 
shall not be operable at any combination of tube potential and current 
that will result in an AKR in excess of 88 mGy per minute (vice 10 R/
min exposure rate) in either mode at the measurement point specified in 
Sec.  1020.32(d)(3), except as specified in Sec.  1020.32(d)(1)(v).
    (iv) Equipment may be modified in accordance with Sec.  1020.30(q) 
to comply with Sec.  1020.32(d)(2). When the equipment is modified, it 
shall bear a label indicating the date of the modification and the 
statement:
Modified to comply with 21 CFR 1020.32(h)(2).
    (v) Exceptions:
    (A) During recording of fluoroscopic images, or
    (B) When a mode of operation has an optional high-level control, in 
which case that mode shall not be operable at any combination of tube 
potential and current that will result in an AKR in excess of the rates 
specified in Sec.  1020.32(d)(1)(i), (d)(1)(ii), or (d)(1)(iii) at the 
measurement point specified in Sec.  1020.32(d)(3), unless the high-
level control is activated. Special means of activation of high-level 
controls shall be required. The high-level control shall be operable 
only when continuous manual activation is provided by the operator. A 
continuous signal audible to the fluoroscopist shall indicate that the 
high-level control is being employed.
    (2) Fluoroscopic equipment manufactured on or after May 19, 1995--
(i) Shall be equipped with AERC if operable at any combination of tube 
potential and current that results in an AKR greater than 44 mGy per 
minute (vice 5 R/min exposure rate) at the measurement point specified 
in Sec.  1020.32(d)(3). Provision for manual selection of technique 
factors may be provided.
    (ii) Shall not be operable at any combination of tube potential and 
current that will result in an AKR in excess of 88 mGy per minute (vice 
10 R/min exposure rate) at the measurement point specified in Sec.  
1020.32(d)(3), except as specified in Sec.  1020.32(d)(2)(iii):
    (iii) Exceptions:
    (A) For equipment manufactured prior to June 10, 2006, during the 
recording of images from a fluoroscopic image receptor using 
photographic film or a video camera when the x-ray source is operated 
in a pulsed mode.
    (B) For equipment manufactured on or after June 10, 2006, during 
the recording of images from the fluoroscopic image receptor for the 
purpose of providing the user with a recorded image(s) after 
termination of

[[Page 34041]]

the exposure. Such recording does not include images resulting from a 
last-image-hold feature that are not recorded.
    (C) When a mode of operation has an optional high-level control and 
the control is activated, in which case the equipment shall not be 
operable at any combination of tube potential and current that will 
result in an AKR in excess of 176 mGy per minute (vice 20 R/min 
exposure rate) at the measurement point specified in Sec.  
1020.32(d)(3). Special means of activation of high-level controls shall 
be required. The high-level control shall be operable only when 
continuous manual activation is provided by the operator. A continuous 
signal audible to the fluoroscopist shall indicate that the high-level 
control is being employed.
    (3) Measuring compliance. Compliance with paragraph (d) of this 
section shall be determined as follows:
    (i) If the source is below the x-ray table, the AKR shall be 
measured at 1 cm above the tabletop or cradle.
    (ii) If the source is above the x-ray table, the AKR shall be 
measured at 30 cm above the tabletop with the end of the beam-limiting 
device or spacer positioned as closely as possible to the point of 
measurement.
    (iii) In a C-arm type of fluoroscope, the AKR shall be measured at 
30 cm from the input surface of the fluoroscopic imaging assembly, with 
the source positioned at any available SID, provided that the end of 
the beam-limiting device or spacer is no closer than 30 cm from the 
input surface of the fluoroscopic imaging assembly.
    (iv) In a C-arm type of fluoroscope having an SID less than 45 cm, 
the AKR shall be measured at the minimum SSD.
    (v) In a lateral type of fluoroscope, the air kerma rate shall be 
measured at a point 15 cm from the centerline of the x-ray table and in 
the direction of the x-ray source with the end of the beam-limiting 
device or spacer positioned as closely as possible to the point of 
measurement. If the tabletop is movable, it shall be positioned as 
closely as possible to the lateral x-ray source, with the end of the 
beam-limiting device or spacer no closer than 15 cm to the centerline 
of the x-ray table.
    (4) Exemptions. Fluoroscopic radiation therapy simulation systems 
are exempt from the requirements set forth in paragraph (d) of this 
section.
    (e) [Reserved]
    (f) Indication of potential and current. During fluoroscopy and 
cinefluorography, x-ray tube potential and current shall be 
continuously indicated. Deviation of x-ray tube potential and current 
from the indicated values shall not exceed the maximum deviation as 
stated by the manufacturer in accordance with Sec.  1020.30(h)(3).
    (g) Source-skin distance. (1) Means shall be provided to limit the 
source-skin distance to not less than 38 cm on stationary fluoroscopes 
and to not less than 30 cm on mobile and portable fluoroscopes. In 
addition, for fluoroscopes intended for specific surgical application 
that would be prohibited at the source-skin distances specified in this 
paragraph, provisions may be made for operation at shorter source-skin 
distances but in no case less than 20 cm. When provided, the 
manufacturer must set forth precautions with respect to the optional 
means of spacing, in addition to other information as required in Sec.  
1020.30(h).
    (2) For stationary, mobile, or portable C-arm fluoroscopic systems 
manufactured on or after June 10, 2006, having a maximum source-image 
receptor distance of less than 45 cm, means shall be provided to limit 
the source-skin distance to not less than 19 cm. Such systems shall be 
labeled for extremity use only. In addition, for those systems intended 
for specific surgical application that would be prohibited at the 
source-skin distances specified in this paragraph, provisions may be 
made for operation at shorter source-skin distances but in no case less 
than 10 cm. When provided, the manufacturer must set forth precautions 
with respect to the optional means of spacing, in addition to other 
information as required in Sec.  1020.30(h).
    (h) Fluoroscopic irradiation time, display, and signal. (1)(i) 
Fluoroscopic equipment manufactured before June 10, 2006, shall be 
provided with means to preset the cumulative irradiation time of the 
fluoroscopic tube. The maximum cumulative time of the timing device 
shall not exceed 5 minutes without resetting. A signal audible to the 
fluoroscopist shall indicate the completion of any preset cumulative 
irradiation-time. Such signal shall continue to sound while x-rays are 
produced until the timing device is reset. Fluoroscopic equipment may 
be modified in accordance with Sec.  1020.30(q) to comply with the 
requirements of Sec.  1020.32(h)(2). When the equipment is modified, it 
shall bear a label indicating the statement:
Modified to comply with 21 CFR 1020.32(h)(2).
    (ii) As an alternative to the requirements of this paragraph, 
radiation therapy simulation systems may be provided with a means to 
indicate the total cumulative exposure time during which x-rays were 
produced, and which is capable of being reset between x-ray 
examinations.
    (2) For x-ray controls manufactured on or after June 10, 2006, 
there shall be provided for each fluoroscopic tube:
    (i) A display of the fluoroscopic irradiation time at the 
fluoroscopist's working position. This display shall function 
independently of the audible signal described in Sec.  
1020.32(h)(2)(ii). The following requirements apply:
    (A) When the x-ray tube is activated, the fluoroscopic irradiation 
time in minutes and tenths of minutes shall be continuously displayed 
and updated at least once every 6 seconds.
    (B) The fluoroscopic irradiation time shall also be displayed 
within 6 seconds of termination of an exposure and remain displayed 
until reset.
    (C) Means shall be provided to reset the display to zero prior to 
the beginning of a new examination or procedure.
    (ii) A signal audible to the fluoroscopist shall sound for each 
passage of 5 minutes of fluoroscopic irradiation time during an 
examination or procedure. The signal shall sound until manually reset 
or, if automatically reset, for at least 2 second.
    (i) Mobile and portable fluoroscopes. In addition to the other 
requirements of this section, mobile and portable fluoroscopes shall 
provide an image receptor incorporating more than a simple fluorescent 
screen.
    (j) Display of last-image-hold (LIH). Fluoroscopic equipment 
manufactured on or after June 10, 2006, shall be equipped with means to 
display LIH image following termination of the fluoroscopic exposure.
    (1) For an LIH image obtained by retaining pretermination 
fluoroscopic images, if the number of images and method of combining 
images are selectable by the user, the selection shall be indicated 
prior to initiation of the fluoroscopic exposure.
    (2) For an LIH image obtained by initiating a separate 
radiographic-like exposure at the termination of fluoroscopic imaging, 
the techniques factors for the LIH image shall be selectable prior to 
the fluoroscopic exposure, and the combination selected shall be 
indicated prior to initiation of the fluoroscopic exposure.
    (3) Means shall be provided to clearly indicate to the user whether 
a displayed image is the LIH radiograph or fluoroscopy. Display of the 
LIH radiograph shall be replaced by the fluoroscopic image concurrently 
with re-initiation of fluoroscopic exposure, unless separate displays 
are provided for the LIH radiograph and fluoroscopic images.

[[Page 34042]]

    (4) The predetermined or selectable options for producing the LIH 
radiograph shall be described in the information required by Sec.  
1020.30(h). The information shall include a description of any 
technique factors applicable for the selected option and the impact of 
the selectable options on image characteristics and the magnitude of 
radiation emissions.
    (k) Displays of values of AKR and cumulative air kerma. 
Fluoroscopic equipment manufactured on or after June 10, 2006, shall 
display at the fluoroscopist's working position the AKR and cumulative 
air kerma. The following requirements apply for each x-ray tube used 
during an examination or procedure:
    (1) When the x-ray tube is activated and the number of images 
produced per unit time is greater than six images per second, the AKR 
in mGy/min shall be continuously displayed and updated at least once 
every second.
    (2) The cumulative air kerma in units of mGy shall be displayed 
either within 5 seconds of termination of an exposure or displayed 
continuously and updated at least once every 5 seconds.
    (3) The display of the AKR shall be clearly distinguishable from 
the display of the cumulative air kerma.
    (4) The AKR and cumulative air kerma shall represent the value for 
conditions of free-in-air irradiation at one of the following reference 
locations specified according to the type of fluoroscope. The reference 
location shall be identified and described specifically in the 
information provided to users according to Sec.  1020.30(h)(6)(iii).
    (i) For fluoroscopes with x-ray source below the x-ray table, x-ray 
source above the table, or of lateral type, the reference locations 
shall be the respective locations specified in Sec.  1020.32(d)(3)(i), 
(d)(3)(ii), or (d)(3)(v) for measuring compliance with air-kerma rate 
limits.
    (ii) For C-arm fluoroscopes, the reference location shall be 15 cm 
from the isocenter toward the x-ray source along the beam axis. 
Alternatively, the reference location shall be at a point specified by 
the manufacturer to represent the location of the intersection of the 
x-ray beam with the patient's skin.
    (5) Means shall be provided to reset to zero the display of 
cumulative air kerma prior to the commencement of a new examination or 
procedure.
    (6) The displayed AKR and cumulative air kerma shall not deviate 
from the actual values by more than 35 percent over the 
range of 6 mGy/min and 100 mGy to the maximum indication of AKR and 
cumulative air kerma, respectively. Compliance shall be determined with 
an irradiation time greater than 3 seconds.

0
5. Amend Sec.  1020.33 by revising paragraph (h)(2) to read as follows:


Sec.  1020.33  Computed tomography (CT) equipment.

* * * * *
    (h) * * *
    (2) For systems that allow high voltage to be applied to the x-ray 
tube continuously and that control the emission of x-ray with a 
shutter, the radiation emitted may not exceed 0.88 milligray (vice 100 
milliroentgen exposure) in 1 hour at any point 5 cm outside the 
external surface of the housing of the scanning mechanism when the 
shutter is closed. Compliance shall be determined by measurements 
average over an area of 100 square cm with no linear dimension greater 
than 20 cm.
* * * * *

    Dated: May 31, 2005.
Jeffrey Shuren,
Assistant Commissioner for Policy.
[FR Doc. 05-11480 Filed 6-7-05; 10:51 am]
BILLING CODE 4160-01-S