[Federal Register Volume 67, Number 237 (Tuesday, December 10, 2002)]
[Proposed Rules]
[Pages 76056-76094]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-30550]



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Part VII





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; Proposed Rule

  Federal Register / Vol. 67, No. 237 / Tuesday, December 10, 2002 / 
Proposed Rules  

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DEPARTMENT OF HEALTH AND HUMAN SERVICES

Food and Drug Administration

21 CFR Part 1020

[Docket No. 01N-0275]
RIN 0910-AC34


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

AGENCY: Food and Drug Administration, HHS.

ACTION: Proposed rule.

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SUMMARY: The Food and Drug Administration (FDA) is proposing to amend 
the performance standard for diagnostic x-ray systems and their major 
components. The agency is taking this action to update the standard to 
account for changes in technology and use of radiographic and 
fluoroscopic systems as well as to fully utilize the currently accepted 
metric system of units in the standard. For clarity and ease of 
understanding, FDA is republishing the complete contents of the 
affected regulations. 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: Submit written or electronic comments by April 9, 2003. See 
section III of this document for the proposed effective date of a final 
rule based on this document. Submit written comments on the information 
collection requirements by January 9, 2003.

ADDRESSES: Submit written comments to the Dockets Management Branch 
(HFA-305), Food and Drug Administration, 5630 Fishers Lane, rm. 1061, 
Rockville, MD 20852. Submit electronic comments to http://www.fda.gov/dockets/ecomments. Submit written comments regarding the information 
collection requirements to the Office of Information and Regulatory 
Affairs, Office of Management and Budget (OMB), New Executive Office 
Bldg., 725 17th St., NW. rm. 10235, Washington, DC 20503, Attn: Desk 
Officer for FDA.

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. Proposed Amendments to the Performance Standard for Diagnostic X-
Ray Systems and Their Major Components
    A. Change in the Quantity Used to Describe X-Radiation From 
Exposure to Air Kerma
    B. Clarification of Applicability of Requirements to Account for 
Technological Developments in Fluoroscopic X-Ray Systems Such as 
Digital Imaging, Digital Recording, and New Types of Solid-State X-Ray 
Imaging Devices
    C. Changes and Additions to Definitions and Applicability 
Statements
    D. Information to be Provided to Users (Sec.  1020.30(h))
    E. Increase in Minimum Half-Value Layer (Sec.  1020.30(m)(1))
    F. Change in the Requirement for Fluoroscopic X-Ray Field 
Limitation and Alignment (Sec.  1020.32(b))
    G. Revisions and Change in the Limits to Maximum Air Kerma Rate 
(Sec.  1020.32(d) and (e))
    H. New Modes of Image Recording
    I. Entrance Air Kerma Rate at the Fluoroscopic Image Receptor
    J. Requirement for Minimum Source-Skin Distance for Small C-Arm 
Fluoroscopic Systems (Sec.  1020.30(g))
    K. Requirements for Display of Fluoroscopic Irradiation Time, Air 
Kerma Rate, and Cumulative Air Kerma (Sec.  1020.32(h) and proposed 
(k))
    L. ``Last-Image Hold'' Feature on Fluoroscopic Systems (Proposed 
Sec.  1020.32(j))
    M. Modification of Previously Manufactured and Certified Equipment
    N. Modification of Warning Label (Sec.  1020.30(j))
    O. Corrections of Sec.  1020.31(f)(3) and (m)
    P. Corrections to Reflect Changes in Organizational Name, Address, 
and Law (Sec.  1020.30(c), (d), and (q))
    Q. Removal of Reference to Special Attachments for Mammography
    R. Change to the Applicability Statement for Sec.  1020.32
    S. Republication of Sec. Sec.  1020.30, 1020.31, and 1020.32
III. Proposed Effective Date
IV. Environmental Impact
V. Paperwork Reduction Act of 1995
VI. Analysis of Impacts
    A. Introduction
    B. Objective of the Proposed Rule
    C. Risk Assessment
    D. Constraints on the Impact Analysis
    E. Baseline Conditions
    F. The Proposed Amendments
    G. Benefits of the Proposed Amendments
    H. Estimation of Benefits
    I. Costs of Implementing the Proposed Regulations
    J. Small Business Impacts
    K. Reporting Requirements and Duplicate Rules
    L. Conclusion of the Analysis of Impacts
VII. Federalism
VIII. Submission of Comments
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. FDA also develops and 
administers radiation safety performance standards for electronic 
products.
    The purpose of the performance standard and these proposed 
amendments is to improve the public health by reducing exposure to and 
the detriment associated with unnecessary ionizing radiation from 
diagnostic x-ray systems while assuring the clinical utility of the 
images.
    In order for mandatory performance standards to provide the 
intended public health protection, the standards must be modified when 
appropriate to reflect changes in technology or product usage. A number 
of technological developments have been or will soon be implemented for 
radiographic and fluoroscopic x-ray systems. Such developments, 
however, are not addressed in the current standard, but have presented 
problems in the application of the current performance standard.
    FDA thus is proposing to amend the performance standard for 
diagnostic x-ray systems and their major components in Sec. Sec.  
1020.30, 1020.31, 1020.32, and 1020.33(h) (21 CFR 1020.30, 1020.31, 
1020.32, and 1020.33(h)).
    These proposed amendments will require additional features on newly 
manufactured x-ray systems that physicians may use to minimize x-ray 
exposures to patients. Advances in technology have made several of 
these newly required features possible or feasible at minimal 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

[[Page 76057]]

amendments to the performance 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 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 this proposal. In addition, the concepts 
embodied in these proposed 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 (21 U.S.C. 360kk(f)(1)(A)) that FDA is required to consult 
before it may prescribe any electronic product performance standard 
under the act. The proposed amendments themselves were discussed in 
detail with the TEPRSSC during its meeting on September 23 and 24, 
1998. TEPRSSC approved the content of the proposed amendments and 
concurred with their publication for public comment.
    The proposed amendments described in section II of this document 
may be considered as nine significant amendments to the current 
standard and several other minor supporting changes, corrections, or 
clarifications. The nine principal amendments fall into the following 
three categories:
 1. Amendments requiring changes to equipment design and performance;
 2. Amendments designed to improve use of fluoroscopic systems by 
requiring enhanced information to users; and
 3. Amendments applying the standard to new features and technologies 
associated with fluoroscopic systems.

II. Proposed Amendments to the Performance Standard for Diagnostic X-
Ray Systems and Their Major Components

A. Change in the Quantity Used to Describe X-Radiation From Exposure to 
Air Kerma

    FDA proposes to change the quantity and the associated unit used to 
describe the radiation emitted by the x-ray tube or absorbed in air. 
The radiation quantity ``exposure'' would be replaced by the quantity 
``air kerma.'' The units used to describe these quantities would be 
changed accordingly throughout the standard, wherever appropriate.
    The International System of Units (SI) was named and adopted at the 
11th General Conference on Weights and Measures (GCWM) in 1960 as an 
extension of the earlier metric systems. The SI, also referred to as 
the metric system, is the approved system of units for use in the 
United States. The U.S. Department of Commerce published an 
``Interpretation and Modification of the International System of Units 
for the United States'' in the Federal Register on December 10, 1976, 
which set forth the interpretation of the SI system for the United 
States. The Omnibus Trade and Competitiveness Act of 1998 amended the 
Metric Conversion Act of 1975 to require each Federal agency to use the 
metric SI system in its activities. The FDA policy for use of metric 
measurements is described in a March 19, 1990, memorandum. This policy 
calls for use of the metric units followed by a parenthetic ``inch-
pound'' declaration unless there is a cogent reason not to utilize dual 
metric and ``inch-pound'' measurements. The policy notes that there 
should be few such exceptions.
    One of the objectives of the International Commission on Radiation 
Units and Measurements (ICRU) is to develop internationally accepted 
recommendations regarding quantities and units of radiation and 
radioactivity. The ICRU recommendations often form the basis of GCWM 
actions. In 1998, the ICRU published its Report 60, ``Fundamental 
Quantities and Units for Ionizing Radiation,'' superseding its previous 
Report 33. Report 60 uses the SI units and special names for some 
radiation units (Ref. 1). The ICRU had suggested phasing out by 1985 
the use of certain special quantities and units that were not part of 
the SI system, including the special unit of exposure, the roentgen 
(R).
    The current Federal performance standard for diagnostic x-ray 
equipment uses the special quantity exposure to describe the radiation 
emitted from an x-ray system. In the Federal Register of May 3, 1993 
(59 FR 26386), FDA published a final rule which made a partial 
transition to the SI units by changing the unit for exposure from 
``roentgen'' (R) to ``coulomb per kilogram'' (C/kg). This change 
required using an awkward conversion factor of 2.58 x 10-4 
C/kg per R.
    In view of current trends, scientific practice, the U.S. policy, 
and FDA directives, FDA proposes that a complete conversion be made to 
the SI quantities and units by amending the standard to require using 
the quantity air kerma in place of the quantity exposure. Additionally, 
the agency proposes that, in making this conversion, the absolute 
magnitude of the limits on radiation contained in the standard not be 
changed. This requires that the limits, when expressed in the new 
quantity air kerma and its unit, the gray, be expressed with numerical 
values different from the current limits that use the quantity 
exposure.
    In its recent reports, the National Council on Radiation Protection 
and Measurement (NCRP) adopted the use of the SI quantity kerma, in 
particular air kerma, to describe the radiation emitted from an x-ray 
system. This change in the NCRP recommendations was made without 
significant concern that previous limits in the voluntary 
recommendations were slightly increased by this change when numerical 
values for the limits were not changed but were expressed in the new 
units. This change in the NCRP recommendations resulted in an increase 
in the limits, compared to previous recommendations, of about 15 
percent.
    FDA is not proposing such an increase in this proposal. Instead, 
FDA is proposing that the numerical values for limits in the standard 
relating to radiation, when expressed in the new quantity, be changed 
as well so the new limits will be equivalent to the current limits, 
thereby making no change to the level of radiation protection provided 
by the standard. FDA has dropped earlier draft proposals to change the 
numerical values in a manner similar to the changes made to the 
voluntary recommendations by the NCRP because of several comments that 
were received. The comments objected to any changes to the level of 
radiation protection provided by the limits in the current mandatory 
standard.
    This proposed approach to the numerical limits results in numerical 
values that are not integer numbers or multiples of 5 or 10, as is the 
case in the current standard, when limits are expressed in the non-SI 
unit for

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exposure, roentgen. For example, the current limit for an exposure rate 
of 10 R/minute (R/min), 2.58 x 10-3 C/kg per min, becomes an 
air kerma rate (AKR) limit of 88 milligray per minute (mGy/min) under 
the proposed approach.
    FDA is proposing new definitions of the quantities kerma, as used 
by the ICRU, and air kerma in Sec.  1020.30(b). Because the quantity 
air kerma is a different quantity from exposure and not numerically 
equivalent, FDA is proposing in the amended standard to express the 
limits in terms of air kerma and indicate the equivalent limit in terms 
of exposure using the word ``vice'' to indicate this equivalence. Thus, 
the change described above would be given in the proposed amendments as 
a limit expressed as ``88 mGy/min (vice 10 R/min)'' indicating that the 
new limit of 88 mGy/min air kerma is equivalent to the previous limit 
10 R/min exposure.
    Current International Electrotechnical Commission (IEC) standards 
for diagnostic x-ray systems use the quantity air kerma to describe the 
radiation emitted by the x-ray system. The current limits on maximum 
fluoroscopic exposure rates in the performance standard were 
established to be consistent with the recommendation of the NCRP. The 
proposed amendment maintains agreement between the performance standard 
and the voluntary standards in terms of the quantities and units used. 
But in order to maintain the current level of radiation protection and 
in response to the comments received, the change results in numerical 
limits for some of the requirements different from those used in the 
current recommendations of the NCRP.
    The term ``exposure'' is also used with a second meaning in the 
performance standard that does not refer to a quantity of radiation as 
defined here. The second meaning of ``exposure'' refers to the process 
or condition during which the x-ray tube is activated by a flow of 
current to the anode and radiation is produced. The second meaning of 
exposure will continue to be used where appropriate. FDA is proposing 
to revise the definition of the quantity exposure in Sec.  1020.30(b) 
to match the current ICRU definition.
    FDA also proposes in Sec.  1020.30(b) to amend the definitions of 
``half-value layer'' (HVL) and ``x-ray field'' to reflect the change 
from the quantity exposure to air kerma.

B. Clarification of Applicability of Requirements to Account for 
Technological Developments in Fluoroscopic X-Ray Systems Such as 
Digital Imaging, Digital Recording, and New Types of Solid-State X-Ray 
Imaging Devices

    When the performance standard was originally developed, the only 
means for producing a fluoroscopic image was either a screen of 
fluorescent material or an x-ray image intensifier tube. Thus, the 
standard was originally written with these two types of image receptors 
in mind. The advent of new types of image receptors, such as solid-
state x-ray imaging (SSXI) devices, and new modes of image recording, 
such as digital recording to computer memory or other media, has made 
the application of the current standard to systems incorporating these 
new technologies cumbersome and awkward. These new aspects of 
fluoroscopic system design have required a series of interpretations to 
apply the standard appropriately. With this in mind, FDA proposes to 
amend the performance standard to recognize these new types of image 
receptors and modes of image recording and to clarify how the 
requirements of the standard apply in each case. This amendment would 
result in replacing the terms ``x-ray image intensifier'' or ``image 
intensifier'' with the more general term ``fluoroscopic image 
receptor'' in numerous sections.
    Although the basic radiation protection and safety requirements for 
fluoroscopic equipment in the performance standard are based on the 
presence of an x-ray image intensifier, these requirements are also 
appropriate for newer imaging systems that do not use an x-ray image 
intensifier. The newer imaging systems may incorporate an image 
receptor consisting of an absorbing material and an array of solid 
state transducers that intercepts x-ray photons and directly converts 
the photon energy into a modulated electrical signal. The signal often 
goes through analog-to-digital conversion as part of the image 
formation process to perform both fluoroscopy and radiography. FDA 
proposes to modify the structure and organization of the standard to 
address this new type of x-ray imaging equipment. The specific changes 
proposed are described below in section II.C of this document.
    For SSXI, new performance considerations are relevant because of 
the different construction and the use of solid-state materials such as 
silicon and selenium. These new considerations include: Changes in 
spatial resolution, as quantified in the modulation transfer function 
(MTF), dynamic range, and detective quantum efficiency; the 
introduction of aliasing artifacts; reduced geometrical efficiency 
(fill factor); and differences in the range of quantum-limited 
operation when compared to the older vacuum-tube-based fluoroscopic 
equipment. Because consensus is not available on some aspects of the 
performance for these new devices, the agency has relied on premarket 
review and associated guidance documents to provide the necessary 
radiation safety control for these devices. (See, e.g., the ``Guidance 
for the Submission of 510(k)s for Solid State X-Ray Imaging Devices '' 
(Ref. 2).)
    An example of a new performance consideration for the SSXI is the 
active detector area. Because of the need for electrical separation/
insulation between individual detector elements, the detector area has 
both active and inactive regions, in terms of detecting image 
information. The relative areas of the active and inactive detector 
areas are usually described in terms of the fill factor. The fill 
factor, to a first approximation, is the pixel area (active area in 
terms of image formation) times the number of pixels divided by the 
total detector area exposed to the input image flux.
    The fill factor and other characteristics can have significant 
effects on imaging performance. The imaging performance must also be 
considered when obtaining a complete picture of the effectiveness of 
these devices. Although FDA is not offering specific proposals for 
imaging performance at this time, FDA is inviting comment on possible 
approaches to ensuring radiation protection and safety in the 
application of these SSXI devices.

C. Changes and Additions to Definitions and Applicability Statements

    To address the changes in technology and the new types of image 
receptors and to allow these items to be appropriately integrated into 
the standard, FDA proposes the following changes in definitions and 
applicability sections of the standard. The changes in definitions 
described here are in addition to those described above in section II.A 
of this document.
    First, in Sec.  1020.30(b), FDA proposes to amend the definition of 
``fluoroscopic imaging assembly,'' ``image receptor,'' ``spot-film 
device,'' and ``x-ray table'' by removing the reference to an x-ray 
image intensifier as the descriptor of the image receptor or by 
replacing image intensifier with the more general term fluoroscopic 
image receptor.

[[Page 76059]]

    Second, FDA also proposes in Sec.  1020.30(b) to amend the 
definition of the term ``recording'' by removing the word ``permanent'' 
and replacing it with the word ``retrievable,'' and to remove the 
examples of ``recording,'' to clarify the definition of the term 
``recording'' in the context of images stored on recording media other 
than film.
    Third, in Sec.  1020.30(b), FDA proposes to clarify the 
applicability of the standard or to bring precision to the meaning of 
specific requirements by adding definitions for the terms solid state 
x-ray imaging device, fluoroscopy, radiography, non-image intensified 
fluoroscopy, automatic exposure rate control, isocenter, last image 
hold (LIH) radiograph, mode of operation, and source-skin distance 
(SSD).
    Last, under Sec.  1020.30(b), FDA proposes to add a definition of 
``lateral fluoroscope'' to clarify the distinction between a lateral 
fluoroscope and what is commonly referred to as a C-arm fluoroscope. In 
an August 29, 1977, Compliance Policy Guide, FDA described the geometry 
for measuring, during a compliance test, the entrance exposure rate for 
lateral fluoroscopes. The standard does not define a system by the way 
it is used but allows the manufacturer to specify the use for which the 
equipment is designed. The design of the system determines whether the 
system is a C-arm or a lateral fluoroscope. If the system is a C-arm, 
it is tested using the test geometry for a C-arm system, even if it is 
used with a lateral beam direction. If the system is a dedicated 
lateral fluoroscope used with a biplane system, the more restrictive 
measurement geometry, as described for a lateral fluoroscope in the 
current Sec.  1020.32(d)(4)(iv) and (e)(3)(iv), will be used. This test 
geometry is described in proposed Sec.  1020.32(d)(3)(v).
    The lateral fluoroscope consists of a support structure holding a 
tube housing assembly and a fluoroscopic imaging assembly with the x-
ray beam in a lateral projection parallel to the plane of the tabletop. 
Thus, the geometry of the source and image receptor is fixed relative 
to the patient or x-ray table. The entrance air kerma would be measured 
with the radiation measurement instrument detector placed 15 
centimeters (cm) from the center of the table in the direction toward 
the x-ray source. (This position is considered to be typical of the 
entrance skin surface of the patient.) During the measurement, the tube 
housing assembly is positioned as close to this location as allowed by 
the system. For C-arm system measurement geometry, the patient is 
assumed to be as close to the image receptor as possible and, 
therefore, the detector is placed 30 cm from the entrance surface of 
the image receptor. In a lateral fluoroscope, the patient cannot be 
placed against the image receptor, and the measurement point is 
referenced to the center of the table. The standard does not require 
that the table have the centerline indicated. Testing is performed 
relative to the centerline and the center is located by measurement if 
necessary.
    Additionally, FDA proposes to correct two minor typographical 
errors that were introduced into the definitions of ``leakage technique 
factors'' and ``spot-film device'' in the May 3, 1993, Federal 
Register.
    FDA proposes in Sec. Sec.  1020.31 and 1020.32 to amend the 
applicability statements by removing the reference to an x-ray image 
intensifier as the descriptor of the image receptor used to distinguish 
between radiography and fluoroscopy. FDA proposes to further modify the 
applicability statements to clearly identify the type of x-ray imaging 
equipment to which each section applies and to distinguish between 
radiographic and fluoroscopic imaging.
    Additionally, to complete the transition to the use of the 
terminology ``fluoroscopic image receptor,'' FDA proposes in Sec.  
1020.32(a)(1) and (a)(2), to replace the term ``image intensifier'' 
with the more inclusive term ``fluoroscopic image receptor'' to reflect 
the changes in fluoroscopic image receptor technology and design. This 
change will, therefore, include SSXI devices, x-ray image intensifiers, 
and other fluoroscopic image receptors within the transmission limit 
and measurement criteria of paragraphs (a)(1) and (a)(2).
    Similarly, FDA proposes in Sec.  1020.32(g) to remove ``image-
intensified fluoroscope'' and add in its place the generic term 
``fluoroscope'' in the description of the requirement for minimum SSD 
for systems intended for specific surgical applications.
    Finally, in Sec.  1020.32(i), FDA proposes to remove the term 
``intensified imaging'' and add in its place ``image receptor 
incorporating more than a simple fluorescent screen.'' This removes the 
reference to a specific type of fluoroscopic image receptor, the image 
intensifier, and includes all types of receptors other than a simple 
fluorescent screen as meeting the requirement of Sec.  1020.32(i).

D. Information to be Provided to Users (Sec.  1020.30(h))

    FDA proposes to add two paragraphs to Sec.  1020.30(h). Proposed 
Sec.  1020.30(h)(5) and (h)(6) would require manufacturers to provide 
in the instructions for users additional information regarding 
fluoroscopic x-ray systems.
    Recent developments in the technology of fluoroscopic systems have 
resulted in equipment being increasingly provided with a variety of 
special modes of operation and methods of recording fluoroscopic 
images. Some of these modes of operation may significantly increase the 
entrance AKR to the patient compared to conventional fluoroscopy. There 
is concern that the operating instructions provided with the 
fluoroscopic system lack sufficient information concerning the 
characteristics of these special modes of operation to permit the 
operator to adequately evaluate the increased radiation output and 
consequent increased exposure to the patient and operator from these 
modes of operation. There is typically little information provided to 
users on the clinical procedure(s) for which each mode was designed, 
resulting in potential inappropriate application of the mode by a user 
who is not fully aware of the intended application of the particular 
mode of operation.
    Proposed Sec.  1020.30(h)(5) would require that the information 
provided to users contain a detailed description of each mode of 
operation and specific instructions on the manner in which the mode is 
engaged or disengaged. The manufacturer would also be required to 
provide information on the specific types of clinical procedures or 
imaging tasks for which the mode is intended and instructions on how 
each mode should be used. This information is to be provided in a 
special section of the user's instruction manual or in a separate 
manual devoted to this purpose.
    Section 1020.30(h)(1)(i) of the performance standard states that 
the information to users shall contain ``Adequate instructions 
concerning any radiological safety procedures and precautions which may 
be necessary because of unique features of the equipment * * *.'' FDA 
considers any mode of operation that yields an entrance AKR above 88 
mGy/min to be a unique feature of the specific fluoroscopic equipment 
and thus must have a full and complete description in the instructions 
for its use.
    FDA is also of the opinion that, for modes of operation where the 
entrance

[[Page 76060]]

AKR exceeds 88 mGy/min, the manufacturer should provide detailed 
information to permit the user to assess the exposure to the patient 
relative to that delivered in the normal mode of operation. Such 
information would give operators important radiation safety data with 
which to make better judgments on the possible hazards involved with a 
particular procedure. FDA has learned that, because of the multiple 
number of modes and options available with many of the systems, many 
users are not aware of when or how such modes are engaged and 
disengaged or the radiation output consequences of such modes. FDA had 
originally considered requiring the manufacturer to provide data on the 
entrance AKRs for each mode of operation of the fluoroscopic system. 
However, the large number of possible combinations of modes and options 
for operation available with many of the systems makes this 
impractical. The proposed amendment described in section II.J of this 
document would require the manufacturer to provide a display of the AKR 
and cumulative air kerma. With this information, the user is made aware 
of the relative changes in the AKR when changing from one mode of 
operation to another. Awareness of such changes will inform the user of 
the relative output changes of the system as a function of mode of 
operation, patient size, and system geometry.
    FDA believes that manufacturers are already providing much of the 
information proposed in this requirement. However, the information may 
not be displayed in a separate section of the manual where users can 
readily find it, and the information may not contain enough detailed 
information on the intended use of the various modes of operation to 
assure proper use of the system.
    Proposed Sec.  1020.30(h)(6) would require manufacturers to provide 
users with information regarding the new features of fluoroscopic 
systems described in proposed Sec.  1020.32(k). Proposed Sec.  
1020.30(h)(6) would also require manufacturers to provide information 
regarding the display of values of AKR and cumulative air kerma. This 
information will include a statement of the maximum deviation of the 
actual values of AKR and cumulative air kerma from their displayed 
values, maintenance and instrumentation calibration information, and a 
description of the spatial coordinates of the reference location for 
which the displayed values are given.

E. Increase in Minimum Half-Value Layer (Sec.  1020.30(m)(1))

    FDA proposes to modify the requirement for minimum HVL to recognize 
changes in x-ray tube and x-ray generator technology over the last few 
decades.
    The use of x-ray filtration to increase the quality or homogeneity 
of an x-ray beam through selective absorption of the low energy photons 
has been a recommended practice for a long time. A 1968 report 
published by NCRP (appendix B, table 3, in Ref. 3) provides the beam 
quality in terms of HVL, as a function of tube potential, that would 
result from specified values of total x-ray filtration in the x-ray 
beam. However, the values of HVL in the table would only result if one 
used the NCRP suggested values of total filtration in diagnostic x-ray 
equipment of that era (i.e., the 1960s to early 1970s). It should be 
noted that diagnostic x-ray equipment of that era was characterized by 
x-ray tubes with a large x-ray target angle and x-ray generators with 
significant ripple in the high voltage waveform (e.g., an x-ray target 
angle of 22[deg] and a high voltage ripple of 25 percent).
    The requirements on beam quality in the current IEC international 
standard (Ref. 4) are also expressed in a similar manner as the NCRP 
Report No. 33 (i.e., a total filtration requirement plus a set of 
minimum HVL values). The Institute of Physical Sciences in Medicine has 
recently published a report which can be used to estimate the total 
filtration from HVL data as a function of x-ray target angle and high 
voltage ripple (Ref. 5). These data point out the lack of 
correspondence between a total filtration of 2.5 millimeters (mm) of 
aluminum and the minimum HVL requirements in the performance standard 
for state-of-the-art x-ray equipment (e.g., an x-ray target angle of 
12[deg] and a high voltage ripple of 10 percent). For these types of 
equipment, the minimum HVL requirements in the performance standard can 
be met with about 1.8 mm of total filtration versus the required 2.5 mm 
of total filtration as specified in the IEC standard (Ref. 4). Only 
equipment with large x-ray target angles (22[deg]) and a great deal of 
high voltage ripple (25 percent) need a total filtration of 2.5 mm of 
aluminum to meet the minimum HVL requirements in the performance 
standard. In terms of skin-sparing effect, the performance-oriented set 
of minimum HVL values in the performance standard have not kept up with 
changes in x-ray equipment when compared to the design-oriented 
requirement of a total filtration of 2.5 mm of aluminum.
    For these reasons, FDA proposes to increase the minimum HVL values 
for radiographic and fluoroscopic equipment excluding mammography 
equipment and dental equipment designed for use with intraoral image 
receptors. The proposed minimum HVL values represent the values 
obtained with a total filtration of 2.5 mm of aluminum on state-of-the-
art diagnostic x-ray equipment (i.e., an x-ray target angle of 12[deg] 
and a high voltage ripple of 10 percent). FDA used the data in the 
Institute of Physical Sciences in Medicine report to arrive at the 
proposed minimum HVL values.
    As a separate x-ray filtration issue, there has been a substantial 
increase over the past 20 years in the use of x-ray fluoroscopy as a 
visualization tool for a wide range of diagnostic and therapeutic 
procedures. Because of the long catheter manipulation times and the 
need, in some cases, for a stationary x-ray field, these procedures 
have the potential, sometimes realized, for high radiation dose to 
patients and clinical personnel (Ref. 6). In fact, the agency has been 
actively involved in promoting recommendations for the avoidance of 
serious, x-ray-induced, skin injuries to patients during 
fluoroscopically-guided interventional procedures. As a result, there 
continues to be an interest in dose reduction techniques for these 
procedures.
    In general, the addition of either beam-hardening or K-edge x-ray 
filters can provide a significant reduction in the exposure, 
particularly skin exposure, to the patient. However, this reduction in 
exposure is accompanied by an attendant increase in tube load (Ref. 7). 
It should be noted that one of the recommendations of the work group on 
the technical aspects of fluoroscopy at the 1992 American College of 
Radiology (ACR)/FDA workshop on fluoroscopy (Ref. 8) was to increase 
the minimum HVL. Therefore, FDA is also proposing an additional 
requirement for fluoroscopic x-ray systems incorporating x-ray tubes of 
high heat-load capacity. Manufacturers of these systems would be 
required to provide a means, at the user's option, for adding 
additional x-ray filtration over and above the amount needed to meet 
the proposed new minimum HVL values. This requirement is based on the 
assumption that x-ray tubes with high heat-load capacity are typically 
required or provided on equipment designed for use in interventional 
procedures due to the imaging task requirements and the extended 
exposure times associated with interventional procedures. The

[[Page 76061]]

method of implementation and the actual values of additional filtration 
to realize the reduction in skin exposure will be left to the 
discretion of the manufacturer.

F. Change in the Requirement for Fluoroscopic X-Ray Field Limitation 
and Alignment (Sec.  1020.32(b))

    FDA proposes to reorganize and add new paragraphs to Sec.  
1020.32(b) to require improved x-ray field limitation for fluoroscopic 
x-ray systems. Section 1020.32(b) would be reorganized to retain the 
current requirements applicable to systems manufactured before the 
effective date of these amendments. For systems manufactured after the 
effective date, new requirements are proposed in Sec.  1020.32(b)(4) 
and (b)(5) respectively, for systems with inherently circular or 
rectangular image receptors. These proposed new requirements will 
result in increased geometric efficiency or more efficient use of 
radiation as described below.
    The proposed reorganization and retention of the existing 
requirements in Sec.  1020.32(b) will be accomplished in the following 
manner: Section 1020.32(b)(1)(i) will be redesignated as Sec.  
1020.32(b)(3); Sec.  1020.32(b)(1)(ii) and (b)(2)(iii) will be combined 
and redesignated as Sec.  1020.32(b)(1) with appropriate revisions to 
paragraph references to reflect the reorganization of Sec.  1020.32(b); 
Sec.  1020.32(b)(2)(iv) will be redesignated as Sec.  1020.32(b)(2) 
with a minor clarification; and Sec.  1020.32(b)(3) will be moved and 
redesignated as new Sec.  1020.32(b)(6). Additionally, Sec.  
1020.32(b)(2)(i) and (b)(2)(ii) will be moved to Sec. 1020.32(b)(4)(i) 
as Sec.  1020.32(b)(4)(i)(A) and (b)(4)(i)(B).
    New requirements of improved efficiency for systems manufactured 
after the effective date of the amendments are proposed in Sec.  
1020.32(b)(4)(ii) for systems with inherently circular image receptors. 
Section 1020.32(b)(5) would contain the field limitation requirements 
for systems with inherently rectangular image receptors. The 
requirements proposed for systems with rectangular image receptors are 
the same as those currently applicable to radiographic systems provided 
with positive beam limitation or to spot-film devices that utilize 
rectangular image receptors. As such, the proposed tolerances for x-ray 
field limitation are considered technically feasible.
    A reduction in unnecessary patient exposure is the basis for all of 
the x-ray field limitation and alignment requirements in the 
performance standard. For example, any radiation falling outside the 
visible area of the image receptor provides no useful diagnostic or 
visualization information and, therefore, represents unnecessary 
patient exposure. Once it is recognized that restricting the size of 
the x-ray field provides an effective control of unnecessary radiation 
exposure, the question shifts to what is the tolerance technically 
achievable by the manufacturer for the matching of the x-ray field and 
the visible area of the image receptor.
    The current performance standard (Sec.  1020.32(b)(2)(i)), states 
``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.'' These requirements result in worst-case values of geometrical 
efficiency enumerated in table 1 of this document for what are typical 
geometrical and operating conditions on fluoroscopic systems. 
Geometrical efficiency is defined as the ratio of the visible area 
divided by the area of the x-ray field. It should be noted that the 
requirements in the existing IEC international standard with respect to 
x-ray field limitation are more stringent than in the performance 
standard (Ref. 4). When the x-ray field is rectangular and the visible 
area is circular, the IEC standard requires that the length and width 
of the x-ray field be less than the diameter of the maximum visible 
area of the image intensifier. Thus, if the x-ray field is centered on 
the visible area of the image intensifier, the x-ray field would exceed 
the visible area of the image intensifier only in the corners of a 
rectangular x-ray field, unlike what could result from following the 
current performance standard.

     Table 1.--Worst-Case Geometrical Efficiency in Percentage for a
                         Fluoroscopic System\1\
------------------------------------------------------------------------
   Visible Area (circular,     X-Ray Field (worst
           cm\2\)             case, square, cm\2\)     Efficiency (%)
------------------------------------------------------------------------
113                                           196                    57
------------------------------------------------------------------------
177                                           289                    61
------------------------------------------------------------------------
415                                           625                    66
------------------------------------------------------------------------
707                                         1,024                    69
------------------------------------------------------------------------
\1\ Worst-Case Geometrical Efficiency in Percentage for a Fluoroscopic
  System With a Source-Image Receptor Distance (SID) of 100 cm, a Square
  X-Ray Field Size at the Limits Allowed by Sec.   1020.32(b)(2)(i), and
  Image Intensifiers With 12-, 15-, 23-, and 30-cm Diameter Visible
  Areas.

    As can be seen from table 1 above, the current performance standard 
allows the possibility of relatively low geometrical efficiency, 
particularly in modes of operation corresponding to small visible areas 
on the image intensifier. It should be noted that many 
fluoroscopically-guided interventional procedures involve the use of 
small visible areas on the image intensifier (Ref. 9). These low values 
of geometrical efficiency are a direct result of using a square 
collimator for the x-ray field when faced with an inherently circular 
visible area for the image receptor. The use of a continuously 
adjustable, circular collimator and/or circular apertures along with 
adjustable rectangular collimation would increase the geometrical 
efficiency.
    Many currently marketed x-ray systems suitable for 
fluoroscopically-guided interventional procedures provide continuously 
adjustable, circular collimators as a basic and/or optional capability 
(Ref. 10). Thus, a continuously adjustable, circular collimator is 
technically feasible, albeit at some additional cost to the user 
community. Fluoroscopic x-ray systems with this feature can provide a 
substantial increase in geometrical efficiency that is important for 
all types of radiological procedures but particularly important for 
interventional procedures resulting in high skin exposure.
    It is for these reasons that FDA proposes to require geometrical 
efficiencies of 80 percent or more for all fluoroscopic x-ray systems. 
When the visible area of the image receptor is

[[Page 76062]]

greater than 34 cm in any direction, a geometrical efficiency of 80 
percent is no longer sufficiently stringent. FDA proposes to change the 
requirement to a sizing tolerance at that point (i.e., the x-ray field 
measured along the direction of greatest misalignment with the visible 
area of the image receptor shall not extend beyond the visible area of 
the image receptor by more than 2 cm). This oversizing tolerance will 
ensure geometrical efficiencies of better than 80 percent for large 
image receptors. In those unusual cases where the x-ray field is not 
uniformly intense over its cross-section, the proposed field limitation 
and alignment requirement provides for measurement of efficiency in 
terms of air kerma integrated over the x-ray field incident on the 
visible area of the image receptor (Ref. 11).
    The intent is to promote the incorporation of continuously 
adjustable, circular collimators into all types of fluoroscopic x-ray 
systems with circular image receptors. FDA acknowledges that the new 
requirements could be met through the use of less complex, currently 
available, rectangular collimation and underframing. For example, the 
amount of underframing (defined as the difference in the width of the 
x-ray field versus the diameter of the visible area) of a rectangular 
x-ray field needed to meet the new requirements is enumerated in table 
2 of this document for the same geometrical and operating conditions of 
fluoroscopic systems described in table 1 of this document. The agency 
is soliciting comments on the ramifications of this amount of 
underframing. These proposed requirements for increased x-ray 
utilization efficiency would appear in proposed Sec.  1020.32(b)(4)(ii) 
for systems manufactured after the effective date of the amendments.

         Table 2.--Underframing of a Rectangular X-Ray Field\1\
------------------------------------------------------------------------
                                X-Ray Field Width
 Visible Area Diameter (cm)           (cm)            Underframing (cm)
------------------------------------------------------------------------
12                                           11.9                  -0.1
------------------------------------------------------------------------
15                                           14.9                  -0.1
------------------------------------------------------------------------
23                                           22.8                  -0.2
------------------------------------------------------------------------
30                                           29.7                  -0.3
------------------------------------------------------------------------
\1\ Amount of Underframing of a Rectangular X-Ray Field Needed to Meet
  the New Field Limitation Requirements for a Fluoroscopic System With
  an SID of 100 cm and Image Intensifiers With 12-, 15-, 23-, and 30-cm
  Diameter Visible Areas.

    Although the field limitation requirements for fluoroscopic 
equipment in the performance standard are predicated on the presence of 
an x-ray image intensifier, the requirements are also appropriate for 
newer imaging systems that do not use an x-ray image intensifier. As 
mentioned previously, the newer imaging systems may incorporate an 
image receptor consisting of an absorbing material backed by an array 
of solid state transducers that intercepts x-ray photons and converts 
the photon energy into a modulated electrical signal with eventual 
analog-to-digital conversion. These image receptors are inherently 
rectangular. As is the case for image intensifier based systems, 
magnification modes are available through the use of a ``digital zoom'' 
where only a selected portion of the digital array is visible to the 
operator. FDA is proposing to apply the current requirements of the 
standard for x-ray field limitation that are used for spot-film devices 
or radiographic systems equipped with positive beam limitation, and 
which also use rectangular fields, to this new type of image receptor. 
These requirements result in worst-case values of geometrical 
efficiency (defined as the square visible area divided by the area of a 
square x-ray field) enumerated in table 3 of this document for what are 
typical geometrical and operating conditions of fluoroscopic systems.

     Table 3.--Worst-Case Geometrical Efficiency in Percentage for a
                         Fluoroscopic System\1\
------------------------------------------------------------------------
    Visible Area Diameter     X-Ray Field (square,
       (square, cm\2\)               cm\2\)            Efficiency (%)
------------------------------------------------------------------------
144                                           196                    73
------------------------------------------------------------------------
225                                           289                    78
------------------------------------------------------------------------
529                                           625                    85
------------------------------------------------------------------------
900                                         1,024                    88
------------------------------------------------------------------------
\1\ Worst-Case Geometrical Efficiency in Percentage for a Fluoroscopic
  System With an SID of 100 cm, a Square X-Ray Field Size at the Limits
  Allowed by Sec.   1020.32(b)(2)(i), and Solid-State X-Ray Images with
  12 cm x 12 cm, 15 cm x 15 cm, 23 cm x 23 cm, and 30 cm x 30 cm Visible
  Areas.

    As can be seen from table 3 above, the current standard provides 
relatively high geometrical efficiency. In this case, the high values 
of geometrical efficiency are a direct result of using a rectangular 
collimator for the x-ray field when faced with an inherently 
rectangular visible area for the image receptor. Proposed Sec.  
1020.32(b)(5) would explicitly state the field limitation requirements 
for systems with inherently rectangular image receptors.

G. Revisions and Change in the Limits to Maximum Air Kerma Rate (Sec.  
1020.32(d) and (e))

    In Sec.  1020.32, FDA proposes to revise and reorganize Sec.  
1020.32(d) and (e) to clarify and simplify the requirements on maximum 
AKR for fluoroscopic x-ray systems. In Sec.  1020.32(d), FDA proposes 
to incorporate all of the requirements for AKR limits regardless of the 
date of manufacture of the x-ray system. The revised paragraph would 
also incorporate the new quantity kerma and the corresponding limits on 
entrance

[[Page 76063]]

AKRs. FDA proposes to move the current requirements of Sec.  1020.32(e) 
that are applicable to equipment manufactured on or after May 19, 1995, 
to the revised Sec.  1020.32(d). This would consolidate all of the 
requirements for limits on the maximum AKR in a single section (i.e., 
revised Sec.  1020.32(d)). Section 1020.32(e) would be reserved.
    The requirements applicable to fluoroscopic systems manufactured 
before May 19, 1995, currently contained in Sec.  1020.32(d)(1) through 
(d)(3), would be contained in revised Sec.  1020.32(d)(1). No change in 
the limit on maximum AKR for previously manufactured fluoroscopic 
systems is introduced by the reorganization and simplification of 
current Sec.  1020.32(d). This simplification is obtained by describing 
the exceptions to the maximum AKR only one time in proposed Sec.  
1020.32(d)(1)(v) rather than three times as in current Sec.  
1020.32(d)(1) through (d)(3).
    Proposed Sec.  1020.32(d)(1) also includes Sec.  1020.32(d)(1)(iv) 
that makes explicit the fact that systems manufactured before May 19, 
1995, may be modified to comply with new requirements contained in 
proposed Sec.  1020.32(d)(2). The rationale for this addition is 
described in section II.M of this document.
    Proposed Sec.  1020.32(d)(2) would include the requirements 
applicable to fluoroscopic systems manufactured on or after May 19, 
1995. Section 1020.32(d)(2)(i) would contain the language currently in 
Sec.  1020.32(e)(1) that requires systems with the capability for AKR 
greater than 44 mGy/min to be provided with automatic exposure rate 
control.
    Section 1020.32(d)(2)(ii) would contain the requirements of current 
Sec.  1020.32(e)(2) that became effective on May 19, 1995, and 
establish an upper limit on the AKR during high-level control mode of 
operation. Section 1020.32(d)(2)(iii) would incorporate the exceptions 
to the maximum AKR limit given in Sec.  1020.32(d)(2)(ii). Section 
1020.32(d)(2)(ii)(A) would contain the exception currently found in 
Sec.  1020.32(e)(2)(i) that addresses the recording of images using a 
pulsed mode applicable to equipment manufactured prior to the effective 
date of these amendments. For equipment manufactured after the 
effective date of these amendments, Sec.  1020.32(d)(2)(ii)(B) would 
add an additional new exception described below in section II.H of this 
document. Finally, the exception currently found in Sec.  
1020.32(e)(2)(ii) addressing high-level control mode of operation would 
be moved to Sec.  1020.32(d)(2)(ii)(C).
    The conditions under which compliance is determined are currently 
found in Sec.  1020.32(d)(4) and (e)(3). These conditions would be 
moved to Sec.  1020.32(d)(3). Section 1020.32(d)(3)(vi) would be added 
to specifically address the measurement conditions for systems with 
SIDs less than 45 cm. For these systems, FDA is proposing that 
compliance be determined by measurement at the minimum SSD.
    The exemption for radiation therapy simulation systems currently 
found in Sec.  1020.32(d)(5) and (e)(4) would be incorporated into a 
proposed revision of Sec.  1020.32(d)(4).

H. New Modes of Image Recording

    New requirements would be established in a Sec.  
1020.32(d)(2)(iii)(B) to further limit the conditions under which the 
limit on the maximum AKR rate would not apply. In May 1994, the agency 
amended the requirements in the standard pertaining to the limit on 
entrance exposure rate (EER) during fluoroscopy. (For convenience in 
discussing the current standard and proposed changes, reference will be 
made to the limits on EER rather than to entrance AKR which will be the 
quantity used in the amended standard.)
    These 1994 amendments prescribed an exception to the limit on EER 
during the recording of images ``from an x-ray image intensifier tube 
using photographic film or a video camera when the x-ray source is 
operated in a pulsed mode.'' (Pulsed mode is defined as 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.) These amendments also prescribed a limit on EER 
of 20 R/min when an optional high-level control was activated during 
fluoroscopy.
    The basic premise of these amendments was to provide for a set of 
limits on the maximum EER during fluoroscopy, and for an exception 
during radiographic modes of operation such as cine-radiography. The 
defining terms for determining whether the equipment was in fluoroscopy 
versus radiography mode of operation were ``recording of images'' and 
``pulsed mode.'' In retrospect, these terms were not explicit enough 
for making a determination of the mode of operation. For example, the 
current wording would allow adding a recording device such as a video 
tape recorder to the imaging chain in a pulsed mode of operation. This 
would, thereby, circumvent the intent of the regulation and allow the 
limit on maximum EER during fluoroscopy to be exceeded, even though the 
recorded images are never used in the radiological examination and are 
used only for archiving purposes, if used at all.
    As mentioned in the earlier discussion on new types of image 
receptors, FDA is proposing new definitions for fluoroscopy and 
radiography. These definitions are needed to make a clearer distinction 
between fluoroscopy and radiography, regardless of the type of image 
receptor being used. A key element in the new definitions is that 
radiographic images recorded from the fluoroscopic image receptor must 
be available for viewing after the acquisition of the images and during 
or after the procedure, whereas fluoroscopic images are viewed in real 
time, or near-real time during the procedure. Thus, the definitions of 
the two modes of operation, i.e., radiography and fluoroscopy, are tied 
to the intended use, and not to an arbitrary interval of time, as under 
the current ``pulsed mode'' definition.
    In addition to the proposed new definitions, FDA proposes to change 
the description of the conditions under which exceptions to the limit 
on maximum AKR are allowed. Section 1020.32(d)(2(iii) would contain two 
exemptions. The exemption currently in Sec.  1020.32(e)(2)(i) would be 
moved to Sec.  1020.32(d)(2)(iii)(A) and would apply to fluoroscopic 
systems manufactured on or after May 19, 1995, but before the effective 
date of the proposed amendment. A new exception would be added in Sec.  
1020.32(d)(2)(iii)(B). This exception would recognize that image 
receptors other than x-ray image intensifiers tubes are now used in 
fluoroscopy and would remove the reference to operation in a pulsed 
mode. Instead, the exception to the limit on maximum AKR would apply to 
any recording of images from the fluoroscopic image receptor except 
when the recording of images is accomplished using a video tape 
recorder or a video disk recorder. This would prevent the simple 
addition of an analog image-recording device to the fluoroscopic system 
as a means to overcome the limit on maximum AKR during normal 
fluoroscopy.
    As discussed in the preamble of the proposed 1993 amendments (58 FR 
26407, May 3, 1993), the agency is still interested in receiving 
information on any clinical situations that could require higher AKR 
than currently permitted. Such situations have been suggested to arise 
due to the necessity of momentarily viewing the patient or the state of 
a device in a patient as best as can be done or with the highest image 
quality obtainable during fluoroscopy

[[Page 76064]]

mode of operation. Some anecdotal evidence seems to argue for an 
increase in the EER above the current 20 R/min limit under high-level 
control. The 1994 change in the regulations underwent an extensive 
review and comment period. The consensus of that review, although not 
unanimous at the time of issuance of the regulations, was that 20 R/min 
would be sufficiently high for most clinical fluoroscopy situations. 
The agency was and is still sensitive to the concern that the limits on 
EER may in some cases compromise the clinical utility of the 
fluoroscopic equipment.
    Because of these concerns regarding the appropriate upper limit 
AKR, FDA is encouraging further comment on the topic of limits on AKR 
under normal and high-level fluoroscopy modes. For example, some 
members of the radiological community have proposed that fluoroscopic 
equipment allow a momentary viewing of the state of an intervention at 
an increased but unspecified AKR. This momentary view would have a 
maximum duration of 10 to 15 seconds. This proposal was accompanied 
with the comment that if physicians are not allowed to use such a mode, 
they will continue the practice of using cineradiography bursts at high 
AKRs to accomplish the clinical task.

I. Entrance Air Kerma Rate at the Fluoroscopic Image Receptor

    Comments received by the agency suggest that an alternative 
approach in place of or in addition to limits on AKR during fluoroscopy 
would be more useful and effective in limiting unnecessary radiation 
and assuring optimum system performance. The suggestion is that the 
limits on AKR to the patient (represented by a measurement made 
according to the compliance geometry described in current Sec.  
1020.32(e)(3)) be replaced by limits on the entrance AKR at the input 
surface of the image receptor (EAKIR). Different EAKIR limits could be 
established for different modes of fluoroscopic imaging, depending on 
the image performance required for the clinical task.
    There is a precedent for this approach in other consensus documents 
such as the NCRP Report No. 99 and NCRP Report No. 102 (Refs. 12 and 
13). For example, the NCRP Report No. 99 states that during fluoroscopy 
``typical image intensifier entrance exposure should be in the range of 
13 to 52 nC/kg/image (50 to 200 microR/image) depending on image 
intensifier size * * *.'' (Note that, in the opinion of FDA, there is 
an error in the NCRP Report No. 99: these numbers reflect exposure per 
second, not exposure per image.) In the same manner, the NCRP Report 
No. 102 provides a table with ``air kerma rate values to produce 
acceptable fluoroscopy images'' and ``air kerma to produce static 
images equivalent to that produced by a par speed screen-film system.'' 
FDA invites comments on the feasibility and desirability of this 
approach to limit unnecessary radiation from fluoroscopic systems.

J. Requirement for Minimum Source-Skin Distance for Small C-Arm 
Fluoroscopic Systems (Sec.  1020.32(g))

    FDA proposes in Sec.  1020.32(g) to add Sec.  1020.32(g)(2) to 
establish a minimum source-skin distance (MSSD) for ``C-arm'' type x-
ray systems having source-to-image-receptor distances of 45 cm or less 
and intended for imaging extremities. This amendment would incorporate 
into the performance standard the content of variances from the 
performance standard granted according to Sec.  1010.4.
    FDA has granted variances from the requirement set out in 
Sec. 1020.32(g) for a limit on the MSSD for fluoroscopic x-ray systems 
that were designed as small portable C-arm systems. These are 
fluoroscopic systems that were originally designed to be hand-held and 
were used at sporting events for a quick examination/diagnosis of 
orthopedic injuries. In fact, some of the early systems used a 
radioisotope instead of an x-ray tube as the source of the radiation 
and were, therefore, outside the purview of FDA under the RCHSA 
(although they are regulated as medical devices). Over time, 
manufacturers of these devices enlarged the distance or opening between 
the x-ray source and the image receptor to allow examination of larger 
extremities. The argument was that some athletes had larger extremities 
and a larger opening was needed to permit the use of the systems on 
them. The systems were marketed under a variance from Sec.  1020.32(g) 
and were labeled for extremity use only. As the size of the opening on 
systems for which variances have been requested has increased from 
about 20 cm to 35 cm, and manufacturers have increased the radiation 
output of these systems, the agency has become concerned about the loss 
of the skin-dose sparing properties of the MSSD requirement. In 
addition, because a variance is granted for a finite time period, 
renewal of the variances and the reviewing of new conditions for use 
present resource implications for FDA and the manufacturers.
    The justification for a variance from Sec.  1020.32(g) used by many 
manufacturers of these small C-arm systems is geometrical scaling. 
Manufacturers have stated in their variance applications that the MSSD 
is proportional to the source-image receptor distance in comparison to 
full-sized C-arm systems. Although extremities can be considered to 
scale geometrically in a similar manner compared to the trunk or large 
body parts, other body parts do not scale in such a manner as to 
maintain a similar skin dose. For the source-image receptor distances 
used in these systems, evaluation of this geometrical relationship 
shows that the factor, by which the entrance AKR to the body part 
increases over that for thinner parts, increases significantly as the 
thickness of the body part being imaged reaches over 15 or 16 cm. This 
increase reaches a factor of two for a thickness of 26 cm and increases 
rapidly for thicker parts. In their original configuration, these 
devices had a very small opening and could not accommodate anything 
other than a limb. The latest configurations can easily accommodate the 
whole body of a neonate or a pediatric patient.
    At some point, these systems no longer represent small C-arms for 
extremity use alone but are simply slightly smaller versions of 
conventional C-arms for whole-body, general-purpose examinations. If 
the system can be used for whole-body examination purposes, it should 
meet the minimum radiation safety standards applicable to conventional 
C-arm systems. Through the variance petition process, FDA has limited 
the small C-arm systems to extremity use only.
    To incorporate the protection provided by the conditions imposed by 
the variances and to incorporate this requirement in the performance 
standard, FDA proposes to limit the source-skin distance to not less 
than 19 cm for fluoroscopic systems having source-image receptor 
distances of 45 cm or less. Provision would be allowed for systems 
designed for specific surgical applications to be operated with a 
source-skin distance of not less than 10 cm. Systems subject to this 
requirement would be required to be labeled for use for imaging 
extremities only. Manufacturers would be required to include 
appropriate precautions in the information provided to users under 
Sec.  1020.30(h).

K. Requirements for Display of Fluoroscopic Irradiation Time, Air Kerma 
Rate, and Cumulative Air Kerma (Sec.  1020.32(h) and Proposed (k))

    FDA is proposing that newly manufactured fluoroscopic systems 
display directly to the fluoroscopist information related to three

[[Page 76065]]

fundamental aspects of patient irradiation--the duration, rate, and 
amount of x-ray emissions. Generally, fluoroscopic systems do not 
currently provide such information at all. Irradiation time, AKR, and 
cumulative air kerma are basic radiological variables important for 
medical radiation protection. Their values may be applied to the 
process of optimization (i.e., obtaining radiological images with the 
least amount of radiation required), to the assessment of radiation 
detriment as a factor affecting patient-outcome efficacy, and to the 
development of reference levels representative of normal clinical 
practice. Optimization, efficacy, and reference levels currently 
comprise a conceptual vanguard of radiation protection in medicine at 
the international level (Refs. 14 to 17). When monitored in the clinic, 
irradiation time, AKR, and cumulative air kerma may be used to indicate 
risk of acute skin injury arising from potentially prolonged 
irradiation associated with some interventional procedures (Refs. 18 to 
20). Values displayed directly to practitioners as an examination or 
procedure progresses can feed back to them indices of radiation burden, 
and practitioners can respond promptly by adjusting protocols and 
techniques to minimize dose to patients and practitioners as 
practitioners optimize radiation levels necessary for medical imaging. 
Moreover, for fluoroscopy and radiography in general, knowledge of 
irradiation levels at patient skin entrance is an essential starting 
place for evaluation of absorbed dose to internal tissues (Refs. 9 and 
21). Such doses are stochastically linked to cancer morbidity, 
mortality, and to genetically transmissible defects (Refs. 14 and 22). 
Estimates of cumulative doses absorbed in tissues foster risk 
communication between medical staff and patients and, when tracked over 
time, are effective indicators of practice consistency, variability, or 
anomaly in the quality assurance activities associated with assuring 
the safety of clinical procedures.
    The need for displays of irradiation variables was recognized at 
the 1992 national workshop on safety issues in fluoroscopy organized by 
the ACR and FDA (Ref. 8). In October 1995, the need was also recognized 
internationally by the workshop on efficacy and radiation safety in 
interventional radiology, sponsored jointly by the World Health 
Organization and the Institute of Radiation Hygiene, Radiation 
Protection Ministry, Federal Republic of Germany (Ref. 23). Recently, 
requirements for displays of irradiation parameters have been 
incorporated into an international standard for x-ray systems for 
interventional radiology (Ref. 24). With the advent of commercially 
available and relatively inexpensive means to measure and display real-
time AKR and cumulative air kerma produced by fluoroscopic systems 
(Ref. 25), it is feasible as well as desirable to require that this 
information be directly observable by fluoroscopists at their working 
positions.
    The proposed display requirements would apply to all types of newly 
manufactured fluoroscopic equipment (i.e., from systems found in 
cardiac catheterization suites, to equipment used for upper 
gastrointestinal fluoroscopy, to ``mini'' C-arms, and also to each 
fluoroscopic x-ray tube as part of any system). FDA invites comments 
about whether these requirements would be suitable to all types, or to 
a limited set of fluoroscopic equipment, namely, to stationary C-arm 
fluoroscopes that are typically used in interventional procedures.
1. Fluoroscopic Irradiation Time, Display, and Signal
    Fluoroscopic irradiation time is profoundly tied to patient dose in 
a complex way that involves many other factors (e.g., see Ref. 26). FDA 
believes it advantageous to require that cumulative irradiation-time 
values be treated in their own right, in addition to the other 
variables cited in the proposed Sec.  1020.32(k), as radiological 
parameters whose control would facilitate radiation-protection 
optimization. Physician members of TEPRSSC pointed out at its September 
1998 meeting that irradiation time is the single fundamental variable 
over which a physician using fluoroscopy has the most direct and 
easiest control through activating or deactivating x-ray production, 
typically by means of a pedal switch (Ref. 27).
    FDA proposes to add Sec.  1020.32(h)(2) to the regulations to 
change the current fluoroscopic timer requirement in two ways. First, 
Sec.  1020.32(h)(2)(i) would require that the values of the cumulative 
irradiation times associated with each of the fluoroscopic tubes of a 
system used in an examination or procedure be displayed to the 
fluoroscopist at his or her working position. The displayed values 
would be indicated from the beginning, throughout, and after an 
examination ends, available until the cumulative irradiation timer is 
reset to zero prior to a new examination. Second, Sec.  
1020.32(h)(2)(ii) would require an audible signal cycle different from 
that of current equipment for each x-ray tube used during an 
examination or procedure. Contrary to the current provision that allows 
the timing device to be preset to any interval up until a maximum 
cumulative irradiation time of 5 minutes, FDA proposes that a signal 
audible to the fluoroscopist sound at each fixed interval of 5 minutes 
of irradiation time. Also contrary to the current requirement, instead 
of sounding until reset, the audible signal would sound (while x-rays 
are produced) for a minimum of only 1 second, after which the signal 
could stop until a subsequent 5 minutes of irradiation elapses. The 
audible signal would not affect the production of x-rays, the display 
of cumulative irradiation-time values required by Sec.  
1020.32(h)(2)(i), or any of the other displays proposed in Sec.  
1020.32(k).
    Considering advice offered at the 1998 TEPRSSC meeting (Ref. 27), 
FDA now believes that a fixed, standard (5 minute) period for an alert 
signal would avoid potential confusion that could ensue with a 
fluoroscopic timer that is variably preset. For example, such confusion 
could arise in a busy clinical facility with many different users, 
where fluoroscopists might not be aware of the need to readjust alert 
intervals that had been changed previously by other fluoroscopists to 
accommodate the individual protocol requirements associated with 
particular patient examinations. Furthermore, FDA believes that an 
audible signal of short duration would be a more effective and useful 
alert than a signal that sounds continuously, requires a reset, and 
therefore, could pose a distraction to users. FDA seeks comments about 
the audible signal cycle in proposed Sec.  1020.32(h)(2)(ii), 
particularly in comparison to the suggested alternative below that is 
not currently in the proposal.
    As an alternative approach, the selection of the time period until 
the alarm sounds could be at the discretion of the fluoroscopist. The 
timer could be preset to any period (less than, equal to, or greater 
than 5 minutes), or preset even to not sound at all. Under this 
approach, before an examination or procedure, the fluoroscopist could 
select a period beyond which an audible signal would sound until the 
timer could be reset (or else sound briefly then remain silent until 
the preset fluoroscopic period elapses again). Presuming clinicians 
maintain personal cognizance of fluoroscopic timer options and 
adaptability, such alternatives would offer them flexibility and 
opportunity to apply standard features of equipment operation to their

[[Page 76066]]

own individual clinical protocols and practices.
    FDA also seeks comment on whether the display of the cumulative 
irradiation time should be visible to the fluoroscopist at his or her 
working position or whether it is sufficient to display the cumulative 
time at the control console. It has been suggested that this display 
should be available to the fluoroscopist to permit constant monitoring 
by the fluoroscopist. Other opinions are that such a display at the 
working position would only add confusion to an already complex visual 
environment, and display of the cumulative irradiation time at the x-
ray control would make the information available in any case. Display 
at the fluoroscopist's working position may be slightly more complex or 
costly than display at the x-ray control.
2. Displays of Air Kerma Rate and Cumulative Air Kerma
    FDA believes that a requirement for displays of AKR and cumulative 
air kerma values would significantly advance the optimization of 
radiation safety, in consideration of recent developments in clinical 
practice and technology (Refs. 23, 25, and 26), an evolving consensus 
for a radiation-protection framework (Refs. 14 to 17), and specific 
guidance (Refs. 18 to 20). Air kerma and AKR are fundamental 
radiological quantities of the amount and rate of charged-particle 
kinetic energy liberated per mass of air traversed by incident x-rays 
(Ref. 1). For this reason, FDA proposes to add Sec.  1020.32(k) to 
require that all new fluoroscopic systems be capable of displaying 
real-time values of the AKR and cumulative air kerma delivered by each 
x-ray tube at reference locations representative of x-ray beam entry to 
the patient skin surface. These displays would be directly discernible 
at the fluoroscopist's working position, and the displayed values would 
deviate by no more than +/-25 percent from actual values. To elucidate 
these requirements and those of the other proposed amendments, the 
definitions of the terms ``fluoroscopy,'' ``mode of operation,'' ``and 
radiography'' are proposed in Sec.  1020.30(b). The utility of the 
display requirements could be broadly leveraged among practitioners in 
a variety of clinical settings through familiarization with relatively 
standardized display formats. Such standardization is proposed in Sec.  
1020.32(k)(1) through (k)(7), where the particular requirements 
proposed conform generally to those of the recently published IEC 
standard (Ref. 24).
    During fluoroscopy or while recording images during a fluoroscopic 
procedure, the displayed value of the AKR would represent in real time 
the magnitude of air kerma per unit time being delivered at any 
geometrical point within a specified reference locus. The displayed 
value of the cumulative air kerma would represent a sum of two parts: 
(1) The fluoroscopic AKR integrated over an interval until update, and 
(2) all contributions to the air kerma (at any point in the same 
reference locus) from radiography occurring in that interval. The 
cumulative air kerma would be updated throughout the examination or 
procedure, and the integration interval would be the time between the 
start of an examination or procedure and the end of the most recent 
episode of either fluoroscopy or radiography during that same 
examination or procedure.
    For each x-ray tube used during fluoroscopy or during recording of 
fluoroscopy, the value of the AKR will be displayed. After the 
cessation of fluoroscopy, the cumulative air kerma will be displayed 
and will remain displayed until the resumption of fluoroscopy or a 
radiographic mode is activated or the display is reset for a new 
patient or procedure. Thus, the cumulative air kerma will be displayed 
after x-ray production ceases from either fluoroscopy or radiography.
    Values of the AKR are displayed at times other than those for the 
cumulative air kerma in order to underscore the distinction between 
these two variables and also to reduce the potential for overwhelming 
the fluoroscopist with too much information presented at once. At any 
particular moment during an examination or procedure, only values of 
the irradiation time and AKR (or cumulative air kerma) would be on 
display for each tube used. If, for example, a biplane fluoroscopic 
system were used in some cardiac catheterization procedure, two 
separate sets of values--one set for each of the x-ray tubes of the 
biplane--would be displayed. Under such circumstances of multiple 
presentations of related information, it is important that the values 
displayed be distinguishable enough from each other to be easily 
recognized and associated with the different radiological variables 
they represent. For this reason, FDA proposes in Sec.  1020.32(h)(2)(i) 
and (k)(3) to require that the units of measurement be displayed as 
well as the values per se. FDA also proposes in Sec.  1020.32(k)(1) and 
(k)(2) to require that the measurement units mGy/min and mGy be 
displayed respectively alongside the values for AKR and cumulative air 
kerma. These values would serve as a labeling distinction to preclude 
potential confusion of the quantities.
    As measures of fundamental radiological quantities, the displayed 
values of AKR and cumulative air kerma would refer to free-in-air 
irradiation conditions (i.e., their evaluations would be made minus any 
contributions of scatter radiation, particularly contributions 
backscattered from a patient (or from a measurement phantom)). Also, 
the displayed values would refer to irradiation conditions at a 
reference location (i.e., at any geometrical point contained within a 
specific reference locus defined according to the type of fluoroscopic 
system). Each reference location is intended to represent, at least 
nominally, a place of x-ray beam entry to the patient skin. For 
fluoroscopes with the x-ray source below or above the table, or of the 
lateral type, Sec.  1020.32(k)(5)(i) would have skin-entrance reference 
locations correspond identically and respectively to those specified in 
Sec.  1020.32(d)(3)(i), (d)(3)(ii), or (d)(3)(v). These locations 
define the geometry for measuring compliance with the regulatory maxima 
of the AKR.
    For C-arm type fluoroscopes, however, in many cases the locations 
proposed for measuring compliance with the regulatory maxima of the 
AKR, given in Sec.  1020.32(d)(3)(iii) and (d)(3)(iv), would not 
suitably represent where the x-ray field enters the patient skin. This 
is especially true for oblique angulations and extended distances 
between the x-ray source and image receptor. Therefore, in Sec.  
1020.32(k)(5)(ii), for C-arm systems, FDA is proposing a skin-entrance 
reference location for display quantities that is different from the 
location for measuring compliance with regulatory AKR limits. For 
evaluation of displayed values, the skin-entrance reference location 
would be either 15 cm from the isocenter toward the x-ray source along 
the beam axis (irrespective of angulation) or, alternatively, along the 
beam axis at a point deemed by the manufacturer to represent the 
intersection of the x-ray beam and the entrance surface of the patient 
skin. A definition of ``isocenter'' is proposed in Sec.  1020.30(b). 
Proposed Sec.  1020.32(k)(5)(ii) would allow manufacturers to choose 
either the 15-cm locus or specify the alternative. The alternative 
locus would offer manufacturers flexibility to provide systems that 
could evaluate AKR and cumulative air kerma in closer proximity to 
actual places of x-ray beam entry to patients than could systems with 
reference skin entrance defined

[[Page 76067]]

generically at a 15-cm locus from the isocenter. An alternative skin-
entrance reference location may be particularly appropriate for mini C-
arm fluoroscopes (i.e., those with SID less than 45 cm, for which the 
15-cm locus from the isocenter may be physically unrealizable). In any 
case, new paragraphs Sec.  1020.30(h)(6)(iii) and (h)(6)(iv) would 
require that manufacturers identify to the user the spatial coordinates 
of the irradiation location to which displayed values refer and also 
provide a rationale justifying any reference location identified as an 
alternative to the 15-cm locus.
    In patient examinations or procedures with C-arm systems, one 
possible result of having reference locations of x-ray beam skin-entry 
different from the measurement sites for AKR compliance is that 
displayed values could actually exceed the regulatory maxima even 
though the system is fully compliant. Such a situation could arise for 
some irradiation geometry when the reference skin-entrance location is 
closer to the x-ray source than is the site for measuring compliance. 
Displayed values of the AKR and cumulative air kerma are intended to 
inform the fluoroscopist of radiation burden to the patient. 
Conversely, the AKR regulatory maxima, practicably measured 30 cm from 
the imaging-assembly input, according to Sec.  1020.32(d)(3)(iii) or at 
the minimum SSD according to Sec.  1020.32(d)(3)(iv), are intended to 
impose upper limits on radiation output that are compatible with the 
levels needed by the imaging chain for adequate fluoroscopic 
visualization.
    Reset of the displays to zero would occur between sessions with 
successive patients. Before reset, a final value of the cumulative air 
kerma may serve to reinforce an association between the culmination of 
a radiological examination or procedure and the radiation burden 
incurred by the patient. FDA believes that the availability of this 
value would greatly facilitate the implementation of previously 
published recommendations (Refs. 18 to 20) on recording information in 
the patient's medical record to identify the potential for serious x-
ray-induced skin injuries in order to avoid them.

L. ``Last-Image Hold'' Feature on Fluoroscopic Systems (Proposed Sec.  
1020.32(j))

    FDA proposes to add a paragraph to require that all fluoroscopic x-
ray systems be provided with a means to continuously display the last 
image acquired prior to termination of exposure.
    The wide availability of electronic methods for the recording and 
displaying of video images makes possible the provision of a ``last-
image hold'' or ``freeze-frame'' capability on fluoroscopic x-ray 
systems. This feature allows the fluoroscopic x-ray system to 
continuously present a static image of the last fluoroscopic scene 
captured or presented at termination of the fluoroscopic exposure. This 
feature also provides the user with the ability to conveniently view 
fluoroscopic images without continuously irradiating the patient.
    This feature is especially useful in procedures such as 
fluoroscopically-guided needle placement for biopsy or drainage, 
catheter or tube placement, and other diagnostic or therapeutic 
interventional procedures. Systems provided with this feature reduce 
fluoroscopic exposure times while enabling extended examination and 
planning during fluoroscopically-guided procedures.
    This capability is provided as a basic or optional feature on many 
currently marketed fluoroscopic systems. Many individuals have 
expressed the opinion that because of the radiation dose reduction 
afforded by such a feature, it should be provided on all new 
fluoroscopic systems. Such a recommendation was strongly endorsed at 
the workshop on fluoroscopy in 1992 (Ref. 8). In addition, a 
requirement for this capability is included in the recently published 
IEC standard for the safety of x-ray equipment for interventional 
radiology (Ref. 24). Establishing this requirement would assure that 
all new fluoroscopic systems have this patient radiation dose reduction 
feature and that it is available when its use is appropriate. Without 
such a requirement, some systems may for economic reasons continue to 
be purchased without this feature, thereby denying dose reduction 
benefits to patients.
    Proposed Sec.  1020.32(j) would permit the displayed image to be 
obtained from the last or a combination of the last few fluoroscopic 
video frames obtained just prior to termination of fluoroscopic 
exposure or by an alternative implementation via a radiographic 
exposure automatically produced at termination of the fluoroscopic 
exposure. Comments are solicited as to whether these approaches to 
implementation of last image-hold are appropriate and needed.

M. Modification of Previously Manufactured and Certified Equipment

    FDA proposes to add language to Sec.  1020.32(d)(1)(iv) and (h) to 
make explicit the opportunity under Sec.  1020.30(q) for modifications 
to be made to existing certified x-ray systems. Modifications are 
currently permitted as long as the modification does not result in a 
failure to comply with the requirements of the performance standard. 
Changes in performance resulting from amendments to the performance 
standard often result in enhanced radiation safety or features not 
available on previously manufactured and certified systems.
    The existing performance standard requires manufacturers to certify 
that their products meet the applicable performance requirements in 
effect at the time of manufacture. Therefore, amendments to the 
performance standard are generally not retroactive and effective dates 
implementing the standard are specified in the regulations. Usually, a 
1-year effective date is provided in order to allow manufacturers time 
to adjust manufacturing and assembly of their products under the new or 
amended regulations. Indeed, it would be unreasonable to require the 
manufacturer to retrofit or to remanufacture previously produced 
products because of a change in the standard for equipment that could 
have a useful life of 20 or more years.
    In particular, the performance requirements regarding maximum 
exposure rate limits (proposed to become maximum AKR limits), 
established in 1994 (59 FR 26402), and the proposed requirements in 
Sec.  1020.32(h) for fluoroscopic timers are requirements or 
performance features that users of older fluoroscopic equipment may 
wish to implement on their systems. The earlier amendment in 1994 and 
the current proposal apply to new equipment manufactured after the 
effective date of the amendment. The language proposed for inclusion in 
Sec.  1020.32(d) and (h) would provide a mechanism for users of older 
equipment to obtain the performance required under the proposed 
amendments. These changes would allow older systems to be modified to 
meet the maximum AKR limit and fluoroscopic timer performance that will 
be required under the proposed requirements.
    The owner of the fluoroscopic system modified under Sec.  
1020.30(q) is responsible for assuring that the modified x-ray system 
complies with the applicable requirements of the performance standard 
following the modification. The modification to the system may be 
accomplished by a third party or by the original equipment 
manufacturer. The system owner, however, is responsible for assuring,

[[Page 76068]]

through contract requirements with the party performing the 
modification or through testing, that the modified system complies with 
the standard following the modification.

N. Modification of Warning Label (Sec.  1020.30(j))

    FDA proposes to modify the language of the warning label required 
by Sec.  1020.30(j). The current statement warns that safe exposure 
factors and operating instructions must be followed. FDA proposes to 
modify the warning label statement by adding the phrase ``maintenance 
schedules.'' This addition incorporates the suggestion of the TEPRSSC 
and further emphasizes the need for diagnostic x-ray systems to be 
properly maintained and calibrated. Manufacturers of diagnostic x-ray 
systems are required under Sec.  1020.30(h)(1)(ii) to provide a 
schedule of the maintenance necessary to keep the equipment in 
compliance with the performance standard. The standard places no 
requirement on owners or users of diagnostic systems to properly 
maintain these systems. However, the revised wording of the warning 
label is intended to alert users and facility administrators of the 
need to properly maintain the systems.

O. Corrections of Sec.  1020.31(f)(3) and (m)

    FDA proposes to correct oversights in Sec.  1020.31(f)(3) and (m) 
that occurred when the July 2, 1999, amendment was published. Section 
1020.31(f)(3) addresses the x-ray field limitation requirement for 
mammographic x-ray systems and Sec.  1020.31(m) addresses the primary 
barrier required for mammographic x-ray systems. Prior to September 30, 
1999 (the effective date of the final rule), the heading to Sec.  
1020.31(m) was ``Transmission limit for image receptor supporting 
devices used for mammography.''
    When an existing radiation safety performance standard is amended, 
the new or modified requirement applies only to products that are 
manufactured after the effective date of the amendment. Normally, the 
requirement that existed prior to the amendment is retained in the Code 
of Federal Regulations (CFR) to provide a record of the requirements of 
the standard applicable to products on their date of manufacture. When 
the final rule amending Sec.  1020.31(f)(3) and (m) was published on 
July 2, 1999, the provisions describing the requirements for equipment 
manufactured prior to September were inadvertently omitted. Thus, the 
CFR (21 CFR part 1020) has no record of the requirements imposed by 
Sec.  1020.31(f)(3) and (m) for equipment manufactured between the 
initial effective dates for Sec.  1020.31(f)(3) and (m) and September 
30, 1999. To correct this oversight, FDA proposes to reinstate the 
provisions describing the requirements that apply to equipment 
manufactured prior to September 30, 1999, under the earlier versions of 
Sec.  1020.31(f)(3) and (m). This correction will provide a record of 
the requirements applicable before September 30, 1999, and close the 
gap that exists as a result of the oversight in the publication of the 
final rule.
    Additionally, further review of this issue revealed that the 
original publication of Sec.  1020.31(f)(3) in 1977 (42 FR 44230) did 
not indicate an effective date for this paragraph, which was November 
1, 1977. FDA proposes to insert the omitted effective date. The 
omission was of little consequence because the original requirement 
reflected the then current designs of mammographic systems. FDA 
proposes to insert the date to provide an accurate record of the 
applicable x-ray field limitation requirements as a function of the 
date of manufacture of mammographic x-ray systems.
    No changes in the previously applicable or current requirements are 
proposed or intended by these corrections to Sec.  1020.31(f)(3) and 
(m). The corrections are only intended to make explicit the current or 
previously applicable requirements that existed on the date of 
manufacture.
    FDA proposes to revise Sec.  1020.31(f) by adding Sec.  
1020.31(f)(3)(i), the requirement applicable to equipment manufactured 
on or after November 1, 1977, and before September 30, 1999. The 
current requirement, applicable to equipment manufactured after 
September 30, 1999, would be Sec.  1020.31(f)(3)(ii). Section 
1020.31(f)(3)(iii) would contain the requirement for permanent markings 
that are applicable to all equipment manufactured after November 1, 
1977.
    FDA proposes to amend Sec.  1020.31(m). Section 1020.31(m)(1) would 
be revised to contain the requirement applicable to systems 
manufactured on or after September 5, 1978, and before September 30, 
1999; such requirement was previously omitted. Section 1020.31(m)(2) 
would be revised to contain the current requirements applicable to 
equipment manufactured after September 30, 1999, in Sec.  
1020.31(m)(2)(i), (m)(2)(ii), (m)(2)(iii), and (m)(2)(iv). Section 
1020.31(m)(3) would be revised to contain the description of the method 
for measuring compliance; such description is common to both Sec.  
1020.31(m)(1) and (m)(2). A minor technical clarification is also 
proposed in Sec.  1020.31(m)(2)(ii) where the term ``x-ray tube'' found 
in current Sec.  1020.31(m)(2) is replaced by the term ``x-ray system'' 
to reflect the fact that it is the x-ray system, not the x-ray tube, 
that controls initiation of x-ray exposure. This change does not change 
the intent or effect of the requirement.

P. Corrections to Reflect Changes in Organizational Name, Address, and 
Law (Sec.  1020.30(c), (d), and (q))

    FDA proposes to amend Sec. 1020.30(c) to reflect the current 
organizational title of the Office of Compliance of the Center for 
Devices and Radiological Health. FDA also proposes in Sec.  1020.30(d) 
to remove the specific address that is subject to change from time to 
time. Additionally, FDA proposes to amend paragraph Sec.  1020.30(q) to 
reflect the transfer of sections 358(a)(5) and 360B(b) of the PHS Act 
to the act by the SMDA.

Q. Removal of Reference to Special Attachments for Mammography

    FDA proposes to remove reference to ``special attachments for 
mammography'' in Sec.  1020.31(d) and (e). The Mammography Quality 
Standards established in part 900 (21 CFR part 900), particularly Sec.  
900.12(b)(1), require that only diagnostic x-ray systems designed 
specifically for mammography be used to perform mammography in the 
United States. Therefore, the use of special attachments intended for 
use with general-purpose diagnostic x-ray systems to perform 
mammography is inappropriate. No such devices may continue to be used, 
and retaining this reference in the standard would imply that such 
devices or components were acceptable.

R. Change to the Applicability Statement for Sec.  1020.32

    FDA proposes in the applicability statement of Sec.  1020.32 to 
remove the reference to ``fluoroscopy'' and replace it with 
``fluoroscopic imaging'' and to remove ``recording of images through an 
image intensifier tube'' and replace this reference with ``radiographic 
imaging when the radiographic images are recorded from the fluoroscopic 
image receptor.'' This change is necessary to clarify the applicability 
of this section and to incorporate the proposed requirements addressing 
the production of radiographic images for the last image hold feature.

S. Republication of Sec. Sec.  1020.30, 1020.31, and 1020.32

    Because of the large number of proposed changes in Sec. Sec.  
1020.30,

[[Page 76069]]

1020.31, and 1020.32, FDA is republishing these entire sections, 
including the proposed amendments, rather than publishing only the 
proposed individual changes to these sections. Although some of the 
paragraphs in these sections are not changed by this proposal, 
republication of the entire sections will result in a more reader-
friendly version when the final regulation is published.

III. Proposed Effective Date

    FDA proposes that any final rule based on this proposal become 
effective 1 year after the date of publication of the final rule in the 
Federal Register.

IV. 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.

V. Paperwork Reduction Act of 1995

A. Summary

    This proposed rule contains information collection provisions that 
are subject to review by OMB under the Paperwork Reduction Act of 1995 
(PRA) (44 U.S.C. 3501-3502). A description of these provisions is given 
in the following paragraphs with an estimate of the annual reporting 
and recordkeeping 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.
    The information collection burden of the current performance 
standard is covered by an existing information collection clearance, 
OMB control number 0190-0025. FDA is seeking new information collection 
clearance for proposed Sec. Sec.  1020.30(h)(5) and (6), and 
1020.32(j)(4).
    FDA invites comments on: (1) Whether the proposed collection of 
information is necessary for the proper performance of FDA's functions, 
including whether the information will have practical utility; (2) the 
accuracy of FDA's estimate of the burden of the proposed collection of 
information, including the validity of the methodology and assumptions 
used; (3) ways to enhance the quality, utility, and clarity of the 
information to be collected; and (4) ways to minimize the burden of the 
collection of information on respondents, including through the use of 
automated collection techniques, when appropriate, and other forms of 
information technology.

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

    Description: FDA is proposing to amend 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 proposed rule would add to Sec.  1020.30(h) paragraphs (5) and 
(6) describing additional information that would need to be included in 
these manuals or instructions. In addition, proposed Sec.  
1020.32(j)(4) would specify additional descriptive information to be 
included in the user manuals for fluoroscopic x-ray systems required by 
Sec.  1020.30(h). This additional information would be descriptions of 
features of the x-ray equipment required by the proposed 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 the proposed amendments. FDA estimates 
the burden of this collection of information as follows:

    Table 4.--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 5.--Estimated Average Annual Reporting Burden for 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 proposed 
amendment (Ref. 33), 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 proposed amendments, for each model of 
fluoroscopic x-ray system that manufacturers continue to market, each 
manufacturer would have to supplement the user instructions to include 
the additional information required by the proposed amendments.
    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 current Sec.  1020.30(h). 
Therefore, it is assumed that no significant additional capital,

[[Page 76070]]

operating, or maintenance costs will occur to 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 proposed requirements is expected to only add a few printed 
pages to these already extensive manuals or documents.
    The burden that will occur to manufacturers from 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) would 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 would be required to 
draft, edit, design, layout, review, and approve the new portions of 
the user's manual or information required by the proposed amendments. 
Hence FDA estimates a total of 360 hours to prepare the new user 
information that would 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 proposed requirement for display of exposure time, air 
kerma rate, 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. It is assumed that the applicability of the new user 
information developed to multiple models will reduce the average burden 
from the 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 a 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 would be 
required is 36,000 hours, as shown in table 4 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 two 
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 proposed amendments, as shown in table 5 of this document.
    In compliance with the PRA (44 U.S.C. 3507(d)), the agency has 
submitted the information collection provisions of this proposed rule 
to OMB for review. Interested persons are requested to send comments 
regarding information collection to the Office of Information and 
Regulatory Affairs, OMB (see ADDRESSES).

VI. Analysis of Impacts

A. Introduction

    FDA has examined the impacts of this proposed rule under Executive 
Order 12866, the Regulatory Flexibility Act (5 U.S.C. 601-612), and the 
Unfunded Mandates Reform Act of 1995 (Public Law 104-4) (UMRA). 
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 proposed rule is consistent with the regulatory philosophy and 
principles identified in the Executive order. In addition the proposed 
rule is economically significant under Executive Order 12866 and is 
major under the Congressional Review Act. Therefore the proposal is 
subject to review under the Executive order.
    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 proposed 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.
    Section 202(a) of the UMRA requires that agencies prepare a written 
statement of anticipated costs and benefits before proposing any rule 
that may result in an expenditure by State, local, and tribal 
governments, in the aggregate, or by the private sector, of $100 
million in any one year (adjusted annually for inflation). The UMRA 
does not require FDA to prepare a statement of costs and benefits for 
the proposed rule because the proposed rule is not expected to result 
in any 1-year expenditure that would exceed $100 million adjusted for 
inflation. The current inflation-adjusted statutory threshold is about 
$110 million.
    The agency has conducted preliminary analyses of the proposed rule, 
including a consideration of alternatives, and has determined that the 
proposed rule is consistent with the principles set forth in the 
Executive order and in these statutes. The costs and benefits of the 
proposed rule have been assessed in two separate preliminary analyses 
that are described in section VI of this document and that are 
available at the Dockets Management Branch (see ADDRESSES) for review. 
As reviewed below, these preliminary 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 proposed amendments. The analysis of 
benefits projects an average annual amortized pecuniary savings in the 
first 10 years after the effective date of at least $320 million, with 
an estimated 90 percent confidence interval spanning a range between 
$88.35 million and $1.160 billion. FDA believes this analysis of 
impacts complies with Executive Order 12866, and that the proposed rule 
is a significant regulatory action as defined by the Executive order. 
Because of the preliminary nature of these cost and benefit analyses 
and estimates, FDA requests comments on any aspect of their 
methodologies, assumptions, and projections. Comments may be

[[Page 76071]]

submitted to the Dockets Management Branch (see ADDRESSES).

B. Objective of the Proposed Rule

    The primary objective of the proposed 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 proposed rule 
would 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 proposed rule are to bring the performance standard 
up to date with recent and emerging technological advances in the 
design of fluoroscopic x-ray systems and to assure appropriate 
radiation safety for these designs. The proposed amendments would also 
align the performance standard with performance requirements in current 
international standards that were developed since 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 proposed changes would 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 proposed amendments would require particular x-ray equipment 
features reducing unnecessary radiation exposure and thereby yielding 
net benefits. The amendments are necessary because the market will not 
ensure that these equipment features will be adopted without a 
government mandate for such features. Purchasers in health care 
organizations have no incentive to demand the more expensive x-ray 
equipment that would be required by these new amendments because they 
perceive no institutional economic advantage in doing so as benefits 
accrue mainly to patients. Furthermore, purchasers are more responsive 
to physician attention to an immediate need for diagnostic and 
interventional efficacy from the equipment than to a prospective 
capability to reduce radiation-associated risk to patients many years 
in the future. Patients, also focused on their immediate medical needs, 
will 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 these proposed amendments are 
necessary to realize the net benefits described in the following 
analysis.

C. Risk Assessment

    The risks to health that will be 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. 32), 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 VI.H 
is based on linear interpolations of cancer-mortality risk per dose 
derived from BEIR V table 4-3 (Ref. 22) values reduced by a dose-rate 
effectiveness factor of 2 for solid cancers (Ref. 30). The values used 
in our analysis are represented in the following graph in figure 1 of 
the excess lifetime-probability for death per dose associated with 
radiation exposure.
BILLING CODE 4160-01-S

[[Page 76072]]

[GRAPHIC] [TIFF OMITTED] TP10DE02.058

BILLING CODE 4160-01-C

[[Page 76073]]

    FDA underscores the overarching uncertainty in these projections 
with the following statement adopted from CIRRPC Science Panel Report 
No. 9 (Ref. 30):
    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 would be required by 
three of the proposed amendments will promote the bulk of radiation 
dose reduction and hence cancer risk reduction: (1) Displays of 
radiation time, rate, and dose 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 would 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. 29. We invite comment on these assumptions.
    Until recently, the principle 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 through the proposed amendments.

D. Constraints on the Impact Analysis

    It is FDA's opinion that the proposed amendments would offer public 
health benefits that warrant their costs. However, the agency has had 
difficulty thus far 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 solicits comments, data, and opinions as to 
whether the potential health benefits of the proposed amendments would 
justify their costs. FDA will use all information and comments received 
to revise the impact assessment in reaching a final determination as to 
the appropriateness of the proposed amendments.
    The principal costs associated with the proposed amendments would 
be the increased costs to manufacturers 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 to be significantly less than the upper-limit estimate 
developed. Manufacturers of diagnostic x-ray systems are urged to 
provide detailed comments on the anticipated costs of these amendments 
that will enable refinement of these cost estimates.
    The benefits that are expected to result from these amendments are 
reductions in acute skin injuries and radiation-induced cancers. The 
proposed amendments would have two types of impact that reduce patient 
dose and associated radiation detriment without compromising image 
quality.
    The first type of change involves several newly required equipment 
features that would 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 MSSD 
for mini C-arm fluoroscopic systems. Almost all of the changes that 
directly affect x-ray field size or intensity would 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 would obviate the 
expense for manufacturers to produce more than one line of products for 
a single global marketplace.
    The second type of change that would 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. There is wide support for and anticipation of these new features 
by many knowledgeable users of fluoroscopic systems. Similar 
requirements were recently included in a new international voluntary 
standard.

E. Baseline Conditions

    The cost of the proposed amendments to the x-ray equipment 
performance standard would be borne primarily by manufacturers of 
fluoroscopic systems. The cost for one of the nine proposed amendments 
would also affect manufacturers of radiographic equipment and is 
discussed in detail in Ref. 28. Therefore, this discussion will focus 
primarily on fluoroscopy (i.e., the 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 proposed amendments 
would provide image quality and diagnostic information identical to 
equipment

[[Page 76074]]

meeting current standards. Therefore, the clinical usefulness of the 
images provided would not change. The amendments would 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 
would adversely affect the clinical information or results obtained 
from these procedures. These amendments would 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 would provide 
physicians using fluoroscopic equipment with the means to actively 
monitor patient radiation doses 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. 29, using data from several sources. 
These estimates of the annual numbers of specific procedures were used 
in the estimates of benefit from the proposed amendments. No attempt 
was made to account for changes in the annual numbers of procedures in 
future years, due to the large uncertainties in making such 
projections. FDA also 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, 4,200 
are fluoroscopic system installations. The proposed amendments would 
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 radiographic systems that do not 
currently meet the proposed 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.

F. The Proposed Amendments

    As described in section II of this document, the proposed 
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 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 (LIH feature); 
specification of the MSSD 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 SSXI devices, revisions of the 
applicability sections, and establishment of additional definitions.

G. Benefits of the Proposed Amendments

    The proposed amendments would 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 proposed amendments would 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. In particular, moreover, recent experience has demonstrated 
that in some few cases of fluoroscopically-guided interventional 
procedures with especially long irradiation times, the magnitudes of 
the radiation doses are large enough to cause serious injury to the 
skin. A growing number of patients that are potentially at risk for 
acute and 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 proposed amendments would 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 would 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 is wide 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. 28). Properly maintained and adjusted fluoroscopic 
systems are expected to be able to perform the imaging tasks associated 
with the upper GI exam with

[[Page 76075]]

an entrance AKR of 2 cGy/min or less (Ref. 8). 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 
proposed amendments would facilitate this reduction.
    The proposed features of LIH 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 LIH feature would permit decision-making regarding the 
procedure underway while visualizing the anatomy without continuing to 
expose the patient. The air kerma- and AKR-value displays would 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 would require 
fluoroscopists to take advantage of these proposed features and 
optimize the way they use fluoroscopic systems.
    The potential impact of the change in the beam quality requirement, 
which would apply to most radiographic and all fluoroscopic systems, 
can be seen from the data on beam quality obtained from the FDA 
Compliance Testing Program for the current standard. Since January 1, 
1996, FDA has 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 
proposed amendments were 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 7 demonstrates that the addition of 1.5 to 2.0 mm of aluminum 
(Al) as additional filtration, which is the change required to enable 
systems that just meet the current requirement to meet the proposed HVL 
requirement, would 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 proposed 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. 8). 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 below 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 proposed rules are phased into use in the United 
States. (FDA assumes that 10 years after the effective date of the 
proposed rules all fluoroscopic systems then in use would conform to 
those rules and that associated recurring benefits would 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 discount rate covering the identical 
10-year evaluation period used in the cost analysis (see section VI.I). 
Based on an economic model of society's willingness to pay a premium 
for high-risk jobs, we associate a value of $5 million for each 
statistical death avoided, $25,000 for preclusion of each cancer 
treatment, and $5,000 for preclusion of cancer's psychological impact. 
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). Details, notes, and references for this analysis are 
provided in Ref. 29. The low, middle, and high estimates in table 6 of 
this document correspond respectively to the 5th, median, and 95th 
percentile points of nominal probability distributions. Estimation of 
the confidence intervals associated with these distributions is 
explained in the following paragraphs.

                            Table 6.--Projections of Annual Benefits in United States
            for display, collimation, and filtration rules applied to PTCA, CA, and UGI procedures\1\
----------------------------------------------------------------------------------------------------------------
                                                             5th Percentile        Median        95th Percentile
----------------------------------------------------------------------------------------------------------------
Average Annual Dose and Life Savings in the First 10 Years  ................  ................  ................
 After Effective Date of Proposed Rules
----------------------------------------------------------------------------------------------------------------
 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
----------------------------------------------------------------------------------------------------------------

[[Page 76076]]

 
 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 Proposed Rules
----------------------------------------------------------------------------------------------------------------
 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 ($                   0.03              0.07              0.16
 millions)
----------------------------------------------------------------------------------------------------------------
Total ($ millions)                                                  88.35            320.31          1,160.48
----------------------------------------------------------------------------------------------------------------
\1\ PTCA: percutaneous transluminal coronary angioplasty; CA: cardiac catheterization with coronary
  arterlography or angiography; UGI: upper gastrointestinal fluoroscopy

    For the most part, these projections are based on a benefits 
analysis (Ref. 29, available at 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 proposed amendments (sections 
II.E, II.F, and II.K of this document) 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. Proposed requirements for the source-skin distance for small c-
arm fluoroscopes (section II.J of this document) and for provision of 
the last-image hold feature on all fluoroscopic systems (section II.L 
of this document) will also directly reduce dose, but their dose 
reductions are expected to be much smaller than those associated with 
the preceding proposed 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. 29 and its 
notes and references. That analysis, however, is incomplete insofar as 
it refers only to a single set of point estimates. In order to develop 
a range of projections with a nominally high level of confidence, 
several additional assumptions are needed. Among the most important of 
the underpinnings of the analysis are: (1) The projected percentage 
dose reductions corresponding to the three amendments considered and 
(2) the dependence on the risk estimates for cancer mortality from the 
U.S. National Research Council Committee on the Biological Effects of 
Ionizing Radiation (BEIR V) (Ref. 22). 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. 
29).
    With respect to the dependence on the BEIR V estimates, FDA follows 
two recommendations of the Office of Science and Technology Policy 
(OSTP) Committee on Interagency Radiation Research and Policy 
Coordination (CIRRPC) Science Panel Report No. 9 (Ref. 30) that 
represent the Federal consensus position for radiation risk-benefit 
evaluation: First, we apply a value of 2 as the dose-rate effectiveness 
factor (DREF) in the projections of numbers of solid, non-leukemia 
cancers. Adopting a DREF value of 2 in the analysis nearly halves the 
Ref. 29 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. 22, pp. 171, 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), ICRP Publication 73 (Ref. 16, 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. The second 
recommendation that FDA adopts from CIRPPC Panel Report No. 9 (Ref. 30) 
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. 22). 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. 31).
    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 
relative uncertainty of a factor of 2.3 lower and higher than the modal 
point estimates and corresponding respectively to the 5th and 95th 
percentiles of a nominal distribution of confidence; for the projected 
numbers of lives and years of life spared premature death, the overall 
relative uncertainty is a factor of 3.6 lower and higher.

[[Page 76077]]

I. Costs of Implementing the Proposed Regulations

    Costs to manufacturers of fluoroscopic and radiographic systems 
would increase due to these proposals. FDA would 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 proposed amendments, FDA 
re-examined 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. 33.
    FDA has no information, indication, or economic presumption that 
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 proposed amendments, 
namely, manufacturers and FDA itself. FDA requests any information on 
the costs that would be imposed by these new requirements that would 
aid in refining the cost estimates.
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 would 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 would 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 
would need either modification in the adjustment procedure for the 
collimators (for which new installation and adjustment procedures would 
be developed at an estimated one-time cost of $20,000 per model) or 
collimators would need to be redesigned at an estimated cost of $50,000 
per model. FDA has assumed that one-half of all flouroscopic x-ray 
system models (5 models each for 20 manufacturers) would need 
modifications to meet the new requirement, while the remainder would 
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 models x $50,000). All stationary 
fluoroscopic systems would most likely need redesigned collimators that 
would add an 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 proposals to modify the requirement limiting the maximum 
entrance AKR and to remove the exception to the limit during recording 
of images in analog format using a video recorder will only affect the 
adjustment of newly installed systems having such recording capability. 
This requirement is not expected to impose significant costs.
    FDA is proposing 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 would need to be redesigned (at a maximum 
estimated cost of $50,000 per model) for a one-time estimated 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 results in 
annual cost increases of $16.8 million (4,200 annual installations x 
$4,000).
    The proposed amendments would require that all newly manufactured 
fluoroscopic systems be provided with LIH capability. FDA expects that 
10 fluoroscopic system manufacturers would need to redesign their 
systems to include this technology at a maximum cost of $100,000 per 
manufacturer. Total one-time design costs would equal $1.0 million for 
the industry (10 manufacturers x $100,000). It is estimated that about 
half of the new systems installed would already be equipped with this 
feature. Thus, about half of the newly installed systems that currently 
do not provide this feature would need it. FDA estimates that the cost 
would be an additional $2,000 for each system required to have this 
feature. Thus, annual costs would increase by $4.2 million (2,100 
annual systems x $2,000).
    The amendment clarifying the requirement for MSSD 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 would be $0.2 million. The

[[Page 76078]]

average annualized cost of this proposed change would be negligible.
    In summary, total industry costs for compliance with the amendments 
in the area of equipment design include one-time costs of $25.2 
million. This total equals an average annualized cost (7 percent 
discount rate over 10 years) of $3.6 million. In addition, annual 
recurring costs for new equipment features associated with these 
proposed provisions are expected to equal $26.7 million.
2. Costs Associated With Additional Information for Users
    The proposed amendments would require that additional information 
be provided in the user instructions regarding fluoroscopic systems. 
FDA has estimated that each model of fluoroscopic system would 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. In addition, each newly 
installed system would 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 would include a revised manual for an annual cost 
of approximately $0.1 million.
    Related to the requirements for additional information is the 
proposal to change 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 proposed 
for the standard do not pose any significant new or additional costs on 
manufacturers.
4. FDA Costs Associated With Compliance Activities
    FDA costs would increase due to the increased compliance activities 
that would result from these proposed regulations. In addition, FDA 
would experience implementation costs in developing and publicizing the 
new requirements. FDA has estimated that approximately five full-time 
equivalent employees (FTEs) would be required to implement the proposed 
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 a 7 percent discount rate 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 Proposed Regulation
    The estimated costs of the amendments identified as having any 
significant cost impact are summarized in table 7 of this document. The 
costs are identified as non-recurring costs that must be met initially 
or as annual costs associated with continued production of systems 
meeting the proposed requirements or additional annual enforcement of 
the amendments. The total annualized cost of the proposed regulations 
(averaged over 10 years) equals $30.8 million, of which $30.4 million 
would 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.

                                    Table 7.--Summary of Costs of Amendments
----------------------------------------------------------------------------------------------------------------
                           Non-recurring Costs                           Annual Costs to
 Amendment Described in    to Manufacturers ($   Non-recurring Costs    Manufacturers ($     Annual Costs to FDA
         Section                millions)        to FDA ($ millions)        millions)           ($ millions)
----------------------------------------------------------------------------------------------------------------
II.A                            none                     0.0059             none                  none
----------------------------------------------------------------------------------------------------------------
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 proposed amendments, the average annual cost is estimated to be 
$30.8 million, compared to a projected average annual benefits of $320 
million, within a range estimated between $88 million and $1.2 billion.

J. Small Business Impacts

    FDA believes that it is likely that the proposed rule will have a 
significant impact on a substantial number of small entities and has 
conducted an IRFA. This analysis is designed to assess the impact of 
the proposed rule on small entities and alert any impacted entities of 
the expected impact.
1. Description of Impact
    The objective of the proposed 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 would accomplish this by requiring performance features 
on all fluoroscopic

[[Page 76079]]

x-ray systems that would protect patients and health 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 proposed amendments are small entities.
    The impact of the proposed 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 proposed 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 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.
    A portion of the concern and the unnecessary radiation exposure 
resulting from current fluoroscopic practices might be addressed 
through the establishment of controls and requirements regarding the 
qualifications and training of physicians permitted or allowed to use 
fluoroscopic systems. Such requirements could assure that, contrary to 
the current situation, all physicians using fluoroscopy are adequately 
trained regarding radiation safety practices, proper fluoroscopic 
system use, and methods for assuring that patient doses are maintained 
as low as possible. This alternative was rejected because FDA does not 
have the authority, under current law, 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 efforts alone would not result in the needed 
performance improvement of fluoroscopic x-ray systems. FDA concluded 
that improved use of fluoroscopy requires the dose reduction features 
and operator feedback mechanism regarding patient doses that would be 
provided by the proposed amendments.
    Alternatives to the specific amendments proposed were also 
considered in developing these proposals. These alternatives are 
described in detail in the assessment report developed and filed as 
part of the information supporting these amendments (Ref. 33). FDA 
requests comments on alternatives to these proposed amendments that 
would accomplish the needed public health protection and, in 
particular, any alternatives that could mitigate the impact of the 
proposed amendments on small businesses.
3. Ensuring Small Entity Participation in Rulemaking
    FDA believes it is possible that the proposed regulation could have 
a significant impact on small entities. The impact would occur due to 
increased design and production costs for fluoroscopy systems. FDA 
solicits comment on the nature of this impact and whether there are 
reasonable alternatives that might accomplish the intended public 
health goals.
    The proposed regulation will be available on the Internet at http://www.fda.gov for review by all interested parties, and all comments 
will be considered prior to final implementation of the regulation. In 
addition, FDA will communicate the proposed regulation to manufacturer 
organizations and trade associations as well as parties that have 
previously indicated an interest in amendments to the diagnostic x-ray 
equipment performance standard. The proposed amendments will also be 
brought to the attention of relevant medical professional societies and 
organizations whose members are likely to use fluoroscopic x-ray 
systems. FDA will solicit the assistance of the SBA during the comment 
period to assure that all small manufacturers impacted by the proposed 
amendments are aware of the opportunity to comment on the proposal, 
possible alternatives and its impact.

[[Page 76080]]

K. Reporting Requirements and Duplicate Rules

    FDA has concluded that the proposed 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 proposed rule. The cost in the labeling is addressed 
previously.

L. Conclusion of the Analysis of Impacts

    FDA has examined the impacts of the proposed 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 would be borne by the manufacturers of this 
equipment. FDA believes that the reductions in acute and long-term 
radiation injuries to patients that would be facilitated by the 
proposed amendments would appreciably outweigh the upper-bound costs 
estimated for compliance with the rules. Finally, FDA has concluded 
that it is likely that this proposal would have a significant impact on 
a substantial number of small entities.
    FDA solicits comment on all aspects of this analysis and all 
assumptions used.

VII. Federalism

    FDA has analyzed this proposed rule in accordance with the 
principles set forth in Executive Order 13132. FDA has determined that 
the proposed rule does not contain policies that have 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 the various levels of government. Accordingly, 
the agency has concluded that the rule does not contain policies that 
have federalism implications as defined in the Executive order and, 
consequently, a federalism summary impact statement is not required.

VIII. Submission of Comments

    Interested persons may submit to the Dockets Management Branch (see 
ADDRESSES) written or electronic comments regarding this proposal. Two 
copies of any mailed comments are to be submitted, except that 
individuals may submit one copy. Comments are to be identified with the 
docket number found in brackets in the heading of this document. 
Received comments may be seen in the Dockets Management Branch between 
9 a.m. and 4 p.m., Monday through Friday.

IX. References

    The following references have been placed on display in the Dockets 
Management Branch (see ADDRESSES) and may be seen by interested persons 
between 9 a.m. and 4 p.m., Monday through Friday.
    1. Allisy, A. et al., ``Fundamental Quantities and Units for 
Ionizing Radiation,'' ICRU Report No. 60, International Commission 
on Radiation Units and Measurements, Bethesda, MD, December 1998.
    2. FDA Guidance Document, ``Guidance for the Submission of 
510(k)s for Solid State X-Ray Imaging Devices,'' Food and Drug 
Administration, August 6, 1999.
    3. National Council on Radiation Protection and Measurements, 
``Medical X-Ray and Gamma-Ray Protection for Energies Up to 10 MeV, 
Equipment Design and Use,'' NCRP Report No. 33, Bethesda, MD, 
February 1, 1968.
    4. International Standard, International Electrotechnical 
Commission (IEC) 601-1-3, ``Medical Electrical Equipment--Part 1: 
General Requirements for Safety. 3. Collateral Standard: General 
Requirements for Radiation Protection in Diagnostic X-Ray 
Equipment,'' 1994.
    5. Cranley, K., B. J. Gilmore, and G. W. A. Fogarty, ``Data for 
Estimating X-Ray Tube Total Filtration,'' Institute of Physical 
Sciences in Medicine, Report No. 64, Institute of Physical Sciences 
in Medicine, York, England, 1991.
    6. Shope, T. B., ``Radiation-Induced Skin Injuries From 
Fluoroscopy,'' RadioGraphics, vol. 16, pp. 1195-1199, September 
1996.
    7. 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.
    8. 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.
    9. Stern, S. H. et al., ``Handbook of Selected Tissue Doses for 
Fluoroscopic and Cineangiographic Examination of the Coronary 
Arteries,'' HHS Publication FDA 95-8288, U.S. Department of Health 
and Human Services, Public Health Service, Food and Drug 
Administration, Center for Devices and Radiological Health, 
Rockville, MD, 1995.
    10. Rudin, S. and D. R. Bednarek, ``Spatial Shaping of the Beam: 
Collimation, Grids, Equalization Filters, and Region-of-Interest 
Fluoroscopy,'' A Categorical Course in Physics, Physical and 
Technical Aspects of Angiography and Interventional Radiology 
(syllabus). Eds. S. Balter and T. B. Shope, presented at the 81st 
Scientific Assembly and Annual Meeting of the Radiological Society 
of North America, Chicago, IL, November 1995.
    11. Solomon, E. et al., ``Low-Exposure Scanning-Beam X-Ray 
Fluoroscopy System,'' SPIE, vol. 2708, pp. 140-149, 1996.
    12. National Council on Radiation Protection and Measurements, 
``Quality Assurance for Diagnostic Imaging Equipment,'' NCRP Report 
No. 99, Bethesda, MD, December 30, 1988.
    13. National Council on Radiation Protection and Measurements, 
``Medical X-Ray, Electron Beam and Gamma-Ray Protection for Energies 
up to 50 MeV,'' NCRP Report No. 102, Bethesda, MD, June 30, 1989.
    14. Beninson, D. et al., ``1990 Recommendations of the 
International Commission on Radiological Protection,'' Annals of the 
ICRP, ICRP Publication 60, vol. 21, Nos. 1-3, Pergamon Press, 
Oxford, UK, 1991.
    15. Thornbury, J. R. et al., ``An Introduction to Efficacy in 
Diagnostic Radiology and Nuclear Medicine (Justification of Medical 
Radiation Exposure),'' NCRP Commentary No. 13, National Council on 
Radiation Protection and Measurement, Bethesda, MD, August 1995.
    16. 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.
    17. ``Council Directive 97/43/Euratom of 30 June 1997 on Health 
Protection of Individuals Against the Dangers of Ionizing Radiation 
in Relation to Medical Exposure, and Repealing Directive 84/466/
Euratom,'' Official Journal of the European Communities, No. L 180, 
pp. 22-27, July 9, 1997.
    18. Food and Drug Administration, ``Avoidance of Serious X-Ray-
Induced Skin Injuries to Patients During Fluoroscopically-Guided 
Procedures,'' Food and Drug Administration Important Information for 
Physicians and Other Health Care Professionals, September 9, 1994.
    19. Food and Drug Administration, ``Avoidance of Serious X-Ray-
Induced Skin Injuries to Patients During Fluoroscopically-Guided 
Procedures,'' FDA Public Health Advisory, September 30, 1994.
    20. Food and Drug Administration, ``Recording Information in the 
Patient's Medical Record That Identifies the Potential for Serious 
X-Ray-Induced Skin Injuries Following Fluoroscopically-Guided 
Procedures,'' Food and Drug Administration Important Information for 
Physicians and Other Health Care Professionals, September 15, 1995.
    21. Rosenstein, M. et al., ``Handbook of Selected Tissue Doses 
for the Upper Gastrointestinal Fluoroscopic Examination,'' U.S. 
Department of Health and Human Services, Public Health Service, Food 
and Drug Administration, Center for Devices and Radiological Health, 
FDA Publication 92-8282, Rockville, MD, 1992.
    22. 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.
    23. B[auml]uml, A. et al., Eds., Proceedings of the ``Joint WHO/
ISH Workshop on Efficacy and Radiation Safety Interventional 
Radiology,'' Munich-Neuherberg, Germany, October 9 to 13, 1995, BfS-
ISH Report 178/

[[Page 76081]]

97, Bundesamt f[uuml]r Strahlenschutz, Fachbereich Strahlenhygiene, 
Institut f[uuml]r Strahlenhygiene, Neuherberg, Germany, 1997.
    24. 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.
    25. Gkanatsios, N. A. et al., ``Evaluation of an On-Line Patient 
Exposure Meter in Neuroradiology,'' Radiology, vol. 203, pp. 837-
842, 1997.
    26. Geise, R. A. et al., ``Radiation Doses During Pediatric 
Radiofrequency Catheter Ablation Procedures,'' PACE, Part 1, vol. 
19, pp. 1605-1611, 1996.
    27. Transcript of Proceedings, Twenty-fifth Meeting of the 
Technical Electronic Product Radiation Safety Standards Committee, 
vol. 1, pp. 118-121, Gaithersburg, MD, September, 1998.
    28. Suleiman, O. H. et al., ``Nationwide Survey of Fluoroscopy: 
Radiation Dose and Image Quality,'' Radiology, vol. 203, pp. 471-
476, 1997.
    29. 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.
    30. Rosenstein, M. et al., Committee on Interagency Radiation 
Research and Policy 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.
    31. ``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.
    32. 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.
    33. ``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, November 15, 2000. Also available at http://www.fda.gov/cdrh/radhealth/fluoro/amendxrad.html

List of Subjects in 21 CFR Part 1020

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

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

PART 1020--PERFORMANCE STANDARDS FOR IONIZING RADIATION EMITTING 
PRODUCTS

    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.

    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.
    (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 which are electrically powered or connected 
with the x-ray system manufactured on or after [date 1 year after date 
of publication of the final rule in the Federal Register].
    (ii) Diagnostic x-ray systems, except computed tomography x-ray 
systems, incorporating one or more of such 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 kerma).
    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

[[Page 76082]]

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 by 20 centimeters by 3.8 centimeters.
    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.
    Cantilevered tabletop means a tabletop designed such that the 
unsupported portion can be extended at least 100 centimeters 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] TP10DE02.059

    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
    (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.
    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 d[egr] by dm, where d[egr] is the mean energy 
imparted to matter of mass dm; thus D=d[egr]/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.
    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 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.
    Fluoroscopy means a technique for generating x-ray images and 
presenting them instantaneously and continuously as visible images for 
the purpose of providing the user with a visual display of dynamic 
processes.
    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 for a C-arm gantry moving through a full range of 
rotations about a 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.

[[Page 76083]]

    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 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 selected with a set of technique 
factors or other control settings uniquely associated with the mode. 
Examples of distinct modes of operation include normal fluoroscopy 
(analog or digital), high-level control fluoroscopy, cineradiography 
(analog), digital cineradiography, 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 per exposure series, 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.
    Nonimage-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 Sec.  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, consisting of:
    (1) A transducer layer that intercepts x-ray photons and through a 
single or multistage process converts the photon energy into a 
modulated signal representative of the x-ray image, and
    (2) A matrix of integration and switching elements that are coupled 
to the transducer layer. An electrical signal representing the x-ray 
image is generated by a charge generation and transfer process within 
the integration and switching matrix. The electrical signals may 
undergo analog-to-digital conversion before leaving the panel to 
provide either a digital radiographic or fluoroscopic image.
    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

[[Page 76084]]

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 milliamperes-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 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 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 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 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. 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, Sec.  1020.32, or Sec.  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, Center 
for Devices and Radiological Health. 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 the Center for Devices and Radiological Health in the report 
required under Sec.  1002.10 of this chapter;
    (iii) Repaired components, whether or not removed from the system 
and

[[Page 76085]]

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 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 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

[[Page 76086]]

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 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 [date 1 year after date of publication of the final rule in 
the Federal Register], 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. 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 description of any specific 
clinical procedure(s) and clinical imaging task(s) for which the mode 
is recommended or designed and how each mode should be used.
    (6) Displays of values of AKR and cumulative air kerma. For 
fluoroscopic x-ray systems manufactured on or after [date 1 year after 
date of publication of the final rule in the Federal Register], the 
following shall be provided:
    (i) A statement of the maximum deviations of the AKR and cumulative 
air kerma from their respective displayed values;
    (ii) Instructions, including schedules, for calibrating and 
maintaining any instrumentation associated with measurement or 
evaluation of the AKR and cumulative air kerma;
    (iii) Identification of the spatial coordinates of the irradiation 
location to which displayed values of AKR and cumulative air kerma 
refer according to Sec.  1020.32(k)(5);
    (iv) A rationale for specification of a reference irradiation 
location alternative to 15 centimeters from the isocenter toward the x-
ray source along the beam axis when such alternative specification is 
made according to Sec.  1020.32(k)(5)(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 centimeters with no linear dimension greater than 
20 centimeters.
    (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 centimeters 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 
centimeters with no linear dimension greater than 20 centimeters.
    (m) Beam quality--(1) Half-value layer. The half-value layer (HVL) 
of the useful beam for a given x-ray tube potential shall not be less 
than the appropriate value shown in table 1 of this section under 
``Specified Dental Systems,'' for any dental x-ray system designed for 
use with intraoral image receptors and manufactured after December 1, 
1980; under ``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 [date 1 year after date of publication of the 
final rule in the Federal Register]; and under ``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 [date 1 year after date of publication of the 
final rule in the Federal Register]. If it is necessary to determine 
such HVL at an x-ray tube potential which is not listed in table 1 of 
this section, linear interpolation or extrapolation may be made. 
Positive means\2\ shall be provided to insure 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.

[[Page 76087]]



                                                                        Table 1.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                    X-Ray Tube Voltage (kilovolt peak)                                          Minimum HVL (millimeters 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
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                           60                           1.5                      1.3                       1.5
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                           70                           1.5                      1.5                       1.8
--------------------------------------------------------------------------------------------------------------------------------------------------------
Above 70                                                   71                           2.1                      2.1                       2.4
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                           80                           2.3                      2.3                       2.8
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                           90                           2.5                      2.5                       3.2
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          100                           2.7                      2.7                       3.6
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          110                           3.0                      3.0                       4.1
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          120                           3.2                      3.2                       4.5
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          130                           3.5                      3.5                       5.0
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          140                           3.8                      3.8                       5.4
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          150                           4.1                      4.1                       5.9
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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 or on [date 1 year after date of publication of the final rule in the Federal Register].
\3\All x-ray systems, except dental x-ray systems designed for use with intraoral image receptors, subject to this section and manufactured after [date
  1 year after date of publication of the final rule in the Federal Register].

    (2) Optional filtration. Fluoroscopic systems 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 selecting and adding x-ray filtration to the diagnostic 
source assembly over and above the amount needed to meet the half-value 
layer provisions of Sec.  1020.30(m)(1). The selection of this 
additional x-ray filtration shall be at the option of the user.
    (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 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 a HVL specified in table 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.
------------------------------------------------------------------------
                                                            Aluminum
                         Item                              Equivalent
                                                         (millimeters)
------------------------------------------------------------------------
Front panel(s) of cassette holders (total of all)                   1.0
Front panel(s) of film changer (total of all)                       1.0
Cradle                                                              2.0
Tabletop, stationary, without articulated joints                    1.0
Tabletop, movable, without articulated joint(s)                     1.5
 (including stationary subtop)
Tabletop, with radiolucent panel having one                         1.5
 articulated joint
Tabletop, with radiolucent panel having two or more                 2.0
 articulated joints
Tabletop, cantilevered                                              2.0
Tabletop, radiation therapy simulator                               5.0
------------------------------------------------------------------------


[[Page 76088]]

    (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, Sec.  1020.32, or Sec.  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, and provided the modification of the x-ray 
system does not result in a failure to comply with Sec.  1020.31, Sec.  
1020.32, or Sec.  1020.33.
    3. Revise Sec.  1020.31 to read as follows:


Sec.  1020.31  Radiographic equipment.

    The provisions of this section apply to equipment for the recording 
of images, except equipment for fluoroscopic imaging and for 
radiographic imaging when images are recorded from the fluoroscopic 
image receptor or computed tomography x-ray systems manufactured on or 
after November 28, 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 tube current settings or at two 
settings differing by no more than a factor of 2 where the tube current 
selection is continuous.
    (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 76089]]

    (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 millimeters and the other is greater than 
0.45 millimeters. 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 shall 
be equal to or less than 5 centimeters.
    (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 centimeters or at the maximum SID, whichever is 
less. The average illuminance shall be based upon 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 centimeters 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 
millimeters from the edge of the light field toward the center of the 
field; and I2 is the illuminance 3 millimeters from the edge 
of the light field away from the center of the field. Compliance shall 
be determined with a measuring aperture of 1 millimeter.
    (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 centimeters and/or 36, 40, 48, and 72 inches and nominal image 
receptor dimensions of 13, 18, 24, 30, 35, 40, and 43 centimeters 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 centimeters 
or more, the x-ray field at the minimum SSD shall be containable in a 
circle having a diameter of no more than 7 centimeters; and
    (ii) If the minimum SSD is less than 18 centimeters, the x-ray 
field at the minimum SSD shall be containable in a circle having a 
diameter of no more than 6 centimeters.
    (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 the 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

[[Page 76090]]

permanent markings to indicate the maximum image receptor size for 
which it is designed.
    (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 
centimeters;
    (iii) The x-ray beam axis is within +/-3 degrees of vertical and 
the SID is 90 centimeters to 130 centimeters inclusive; or the x-ray 
beam axis is within +/-3 degrees of horizontal and the SID is 90 
centimeters to 205 centimeters 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 centimeters shall be equal to or 
less than 5 centimeters. 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 centimeters; 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 
centimeters by 5 centimeters.

[[Page 76091]]

    (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 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 centimeters if operable above 50 kVp; or
    (ii) Ten centimeters 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 centimeters.
    (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 mGy (vice 0.03 mR exposure) in 1 minute at 
5 centimeters 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 centimeters, with no linear dimension greater 
than 20 centimeters; and
    (2) An air kerma of 0.88 mGy (vice 100 mR exposure) in 1 hour at 
100 centimeters 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 centimeters with no linear dimension greater 
than 20 centimeters.
    (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 
centimeters 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 
centimeters 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 centimeters with no linear dimension greater than 20 
centimeters. 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.
    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 and for radiographic imaging when images are recorded 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 
centimeters 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 centimeters with no linear dimension greater than 20 
centimeters. If the source is below the tabletop, the measurement shall 
be made with the input surface of the fluoroscopic imaging assembly 
positioned 30 centimeters 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 centimeters. 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 centimeters 
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

[[Page 76092]]

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 the capability of a visible area of greater than 300 square 
centimeters 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 centimeters 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 centimeters 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 centimeters by 
5 centimeters. This paragraph does not apply to nonimage-intensified 
fluoroscopy.
    (3) Nonimage-intensified fluoroscopy. The x-ray field produced by 
nonimage-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 centimeters by 5 
centimeters.
    (4) Fluoroscopy and radiography using the fluoroscopic imaging 
assembly with inherently circular image receptors. (i) For fluoroscopic 
equipment manufactured before [date 1 year after date of publication of 
the final rule in the Federal Register], 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 [date 1 
year after date of publication of the final rule in the Federal 
Register], 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 the visible area of the image receptor is less than or 
equal to 34 cm in any direction: (1) At least 80 percent of the x-ray 
field overlaps the visible area of the image receptor, or (2) at least 
80 percent of the air kerma integrated over the x-ray field is incident 
on the area of the image receptor.
    (B) When the visible area of the image receptor 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 shall 
not extend beyond the visible area of the image receptor by more than a 
total of 2 cm.
    (5) Fluoroscopy and radiography using the fluoroscopic imaging 
assembly with inherently rectangular image receptors. For x-ray systems 
manufactured after [date 1 year after date of publication of the final 
rule in the Federal Register]:
    (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 
fluoroscopic images, 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) of this 
section.
    (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) of this section.
    (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) of 
this section.
    (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(d)(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

[[Page 76093]]

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) of this 
section:
    (iii) Exceptions:
    (A) For equipment manufactured prior to [date 1 year after date of 
publication of the final rule in the Federal Register], 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 [date 1 year after date 
of publication of the final rule in the Federal Register], during the 
recording of images from the fluoroscopic image receptor for the 
purpose of providing the user with an image(s) after termination of the 
exposure. However, the archiving of fluoroscopic or radiographic images 
through the recording of such images in analog format with a video-tape 
or video-disc recorder does not qualify as an exception.
    (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 180 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 centimeter above the tabletop or cradle.
    (ii) If the source is above the x-ray table, the AKR shall be 
measured at 30 centimeters 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 centimeters 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 
centimeters 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 centimeters 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 centimeters 
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 centimeters on stationary 
fluoroscopes and to not less than 30 centimeters 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 
centimeters. 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 mobile or portable C-arm fluoroscopic systems manufactured 
on or after [date 1 year after date of publication of the final rule in 
the Federal Register], having a maximum source-image receptor distance 
of less than 45 centimeters, means shall be provided to limit the 
source-skin distance to not less than 19 centimeters. 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 centimeters. 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 [date 1 year after date of 
publication of the final rule in the Federal Register], shall be 
provided with means to preset the cumulative on-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 
on-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 [date 1 year after 
date of publication of the final rule in the Federal Register], there 
shall be provided for each fluoroscopic tube:
    (i) A display of the value and units of the irradiation time from 
the beginning of a patient examination or procedure. This display shall 
be visible at the fluoroscopist's working position throughout the 
examination or procedure and after it ends. The display shall be able 
to be reset to zero prior to the commencement of a new examination or 
procedure, and it shall function independently of the audible signal 
described in Sec.  1020.32(h)(2)(ii).
    (ii) A signal audible to the fluoroscopist shall indicate the 
passage of irradiation time during an examination or procedure. The 
signal shall sound for at least one second at each interval of 5-
minutes duration of irradiation time.
    (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 [date 1 year after date of publication of the 
final rule in the Federal Register], shall be equipped with means to 
display an LIH radiograph following termination of the fluoroscopic 
exposure.

[[Page 76094]]

    (1) For an LIH radiograph 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 radiograph obtained by initiating a separate 
radiographic exposure, if the techniques factors for the radiographic 
exposure are selectable prior to the exposure, the combination selected 
must 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 reinitiation of fluoroscopic exposure, unless separate displays 
are provided for the LIH radiograph and fluoroscopic images.
    (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 
applicable technique factors for the selected option and the impact of 
the selectable options on image characteristics and radiation dose.
    (k) Displays of values of AKR and cumulative air kerma. 
Fluoroscopic equipment manufactured on or after [date 1 year after date 
of publication of the final rule in the Federal Register], shall 
display at the fluoroscopist's working position values of AKR and 
cumulative air kerma. The following requirements apply for each x-ray 
tube used during an examination or procedure:
    (1) The value displayed for AKR shall be in units of mGy/min and 
shall represent the air kerma per unit time during fluoroscopy and 
while recording during fluoroscopy.
    (2) The value displayed for cumulative air kerma shall be in units 
of mGy; shall include all contributions generated from fluoroscopic and 
radiographic radiation; shall represent the total air kerma accrued 
from the commencement of an examination or procedure and shall be 
updated during the examination or procedure each time that fluoroscopic 
or radiographic x-ray production is deactivated.
    (3) During fluoroscopy and while recording during fluoroscopy, the 
value and units of the AKR shall be displayed. Following fluoroscopy or 
radiography, the value and units of the cumulative air kerma shall be 
displayed.
    (4) The display of the value of the AKR shall be clearly 
distinguishable from the display of the value of the cumulative air 
kerma.
    (5) Values displayed for the AKR and cumulative air kerma shall be 
determined 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 information provided to users according to Sec.  
1020.30(h)(6)(iii).
    (i) For fluoroscopes with x-ray source below the 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 type fluoroscopes, the reference location shall be 
15 centimeters from the isocenter toward the x-ray source along the 
beam axis. Alternatively, the reference location shall be along the 
beam axis at a point deemed by the manufacturer to represent the 
intersection of the x-ray beam entrance surface and the patient skin.
    (6) Means shall be provided to reset to zero the values of AKR and 
cumulative air kerma prior to the commencement of a new examination or 
procedures.
    (7) The AKR and the cumulative air kerma shall not deviate from 
their respective displayed values by more than +/-25 percent.
    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 centimeters 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 centimeters with no linear dimension 
greater than 20 centimeters.
* * * * *

    Dated: July 25, 2002.
Margaret M. Dotzel,
Associate Commissioner for Policy.
[FR Doc. 02-30550 Filed 12-9-02; 8:45 am]
BILLING CODE 4160-01-S