[Federal Register Volume 59, Number 96 (Thursday, May 19, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-12155]


[[Page Unknown]]

[Federal Register: May 19, 1994]


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Part VI





Department of Health and Human Services





_______________________________________________________________________



Food and Drug Administration



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21 CFR Part 1020



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

DEPARTMENT OF HEALTH AND HUMAN SERVICES

Food and Drug Administration

21 CFR Part 1020

[Docket No. 92N-0108]

Federal Performance Standard for Diagnostic X-Ray Systems and Their 
Major Components

AGENCY: Food and Drug Administration, HHS.

ACTION: Final rule.

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SUMMARY: The Food and Drug Administration (FDA) is issuing a final rule 
to amend the Federal performance standard for diagnostic x-ray systems 
and their major components (the performance standard). The amendments 
revise the limits established for maximum patient entrance exposure 
rates for fluoroscopic x-ray systems during high-level control and 
other modes of operation. The revisions are being made due to concerns 
regarding excessively large radiation exposure rates on some 
fluoroscopic x-ray systems. In addition, an inadvertent error is being 
corrected to improve the accuracy of the regulations.

EFFECTIVE DATE: May 19, 1995.

FOR FURTHER INFORMATION CONTACT: Patricia M. Dubill, Center for Devices 
and Radiological Health (HFZ-84), Food and Drug Administration, 5600 
Fishers Lane, Rockville, MD 20857, 301-594-4765.

SUPPLEMENTARY INFORMATION:

I. Background

    Under the Federal Food, Drug, and Cosmetic Act (21 U.S.C. 321 et 
seq.) as amended, FDA is amending the performance standard for 
diagnostic x-ray systems and their major components in Sec. 1020.32 (21 
CFR 1020.32) by revising the limits established for maximum patient 
entrance exposure rates for fluoroscopic x-ray systems during high-
level control and other modes of operation. In the Federal Register of 
August 15, 1972 (37 FR 16461), the performance standard was published 
as a final rule which became effective on August 1, 1974. Since that 
time, there have been several amendments to the performance standard. 
These amendments take into account new technology, clarify 
misinterpreted provisions, or incorporate additional requirements 
determined to be necessary to provide for adequate radiation safety of 
diagnostic x-ray systems.
    FDA determined that further changes to the standard were necessary, 
in view of concerns regarding the potential for unnecessary radiation 
exposures to patients from some current fluoroscopic x-ray system 
designs. Therefore, FDA developed proposed draft amendments to the 
performance standard, which were discussed during a public meeting of 
the Technical Electronic Product Radiation Safety Standards Committee 
(TEPRSSC) on November 14, 1990. The proposed amendments that were 
discussed included the following:
    (1) Replacement of the current two-tier system of entrance exposure 
rate limits applicable during normal fluoroscopy on systems with 
automatic exposure rate control (AERC) with a single upper limit of 
2.58x10-3 coulomb per kilogram (C/kg) per minute (10 roentgens per 
minute (R/min)), regardless of mode of operation;
    (2) Establishment of an upper limit of 5.16x10-3 C/kg per 
minute (20 R/min) on entrance exposure rate during high-level control 
mode of fluoroscopy;
    (3) Establishment of a requirement for an AERC mode of operation 
for any fluoroscopic x-ray system capable of operating at an entrance 
exposure rate greater than 1.29x10-3 C/kg per minute (5 R/min); 
and
    (4) Application of the entrance exposure rate limits discussed in 
paragraphs (1) and (2) above during continuous recording of dynamic 
fluoroscopic images with a videotape recorder or similar device. The 
application of the entrance exposure rate limit during continuous 
recording requires a distinction between the continuous mode of 
operation and various modes of operation in which the x-ray exposure is 
pulsed. Therefore, a definition of pulsed mode of operation is being 
added. This is necessary because a consensus as to appropriate limits 
for the various pulsed recording modes does not exist and further study 
is needed before such a limit is imposed.
    TEPRSSC approved the content of the proposed amendments and 
concurred with publication of them for public comment. FDA proposed the 
amendments to the performance standard in the Federal Register of May 
3, 1993 (58 FR 26407). Interested persons were given until August 2, 
1993, to comment on the proposal. FDA received and considered one 
comment each from a radiological physicist and a professional 
organization representing radiologists and physicists. Both comments 
supported the proposed changes and suggested several additional 
amendments to the standard. These comments also addressed fluoroscopy-
related issues on which FDA specifically solicited comments in the 
preamble to the proposed rule. FDA appreciates having received these 
comments and will consider them in the context of possible future 
rulemaking activities related to fluoroscopic x-ray systems. A summary 
of the comments pertaining to the proposal of May 3, 1993, and FDA's 
responses are discussed below.
     In addition, in the final rule that published in the Federal 
Register of May 3, 1993 (58 FR 26386 at 26398), in Sec. 1020.30(b) (21 
CFR 1020.30(b), the acronym ``SID'' for source-image receptor distance 
was inadvertently omitted. This document is also correcting that error.

II. Summary and Analysis of Comments

    1. Both of the comments received concurred with all of the proposed 
amendments to the performance standard, except that one of the comments 
suggested changing the proposed upper limit on entrance exposure rate 
during the high-level control mode of operation. That comment advocated 
a limit of 3.87x10-3 C/kg per minute (15 R/min), rather than the 
proposed limit of 5.16x10-3 C/kg per minute (20 R/min), but noted 
a lack of objective data to support the recommendation. The other 
comment concurred with the proposed limit of 5.16x10-3 C/kg per 
minute (20 R/min) and noted that a number of manufacturers provide 
equipment which does not exceed 2.58x10-3 C/kg per minute (10 R/
min) during fluoroscopy.
    The comment advocating a lower limit did not submit specific data 
supporting that position. The second comment on the appropriate upper 
limit to be imposed on entrance exposure rate during high-level control 
mode of operation noted that a lower limit was consistent with certain 
existing equipment, but nonetheless supported the limit proposed by 
FDA. After reviewing these comments, FDA concludes that its choice of 
an upper limit is a reasonable one. The objective in establishing such 
a limit is to provide a mode of operation that will reasonably 
accommodate unusual imaging requirements, but also will prevent 
unnecessarily high exposure rates. The limit proposed was based on the 
observation that the majority of fluoroscopic x-ray systems equipped 
with high-level control, which were evaluated in conjunction with FDA 
testing for compliance with the performance standard, are limited to 
maximum entrance exposure rates of less than 5.16x10-3 C/kg per 
minute (20 R/min). The proposed limit was also based on discussions 
with medical physicists regarding their experience in limiting entrance 
exposure rates, which indicated that a limit of 5.16x10-3 C/kg per 
minute (20 R/min) eliminates unnecessarily high exposure rates without 
compromising the use of the equipment. FDA interprets the lack of 
significant adverse comment on this proposal as an indication of 
general agreement with the proposed limit. Therefore, FDA rejects the 
suggestion that a limit of 3.87x10-3 C/kg per minute (15 R/min) be 
established for the maximum entrance exposure rate, and is establishing 
the upper limit of 5.16x10-3 C/kg per minute (20 R/min) as 
proposed.
    FDA notes that recommendations related to limits on entrance 
exposure rate resulted from a workshop on fluoroscopy cosponsored by 
FDA and the American College of Radiology (ACR) in October of 1992 
(Ref. 2). These recommendations generally favored limiting exposure 
rates from fluoroscopic x-ray systems in some manner and included 
suggestions for limiting the maximum exposure rate to the input surface 
of the image intensifier tube. FDA has chosen not to include these 
suggestions in this final rule because they were beyond the scope of 
the proposal. FDA will carefully consider the recommendations from the 
workshop related to limiting exposure rates in conjunction with future 
amendments.
    2. One of the comments suggested that the requirement for a 
continuous audible signal during the high-level control mode of 
operation be modified to specify that the signal be emitted at the 
fluoroscopic imaging assembly (at an FDA-specified volume level), to 
ensure that the signal is audible to the fluoroscopist.
    The current requirement for a continuous audible signal is that the 
signal must be audible to the fluoroscopist, which would seem to meet 
the intent of the comment. As with any medical device alarm or signal, 
the volume level of the signal should be designed to be sufficiently 
loud to alert the operator to the status of the device, taking into 
account any background noise likely to be present during use. In 
addition, the effect of an overly loud signal on the patient should be 
considered in the signal design. FDA disagrees that the agency should 
specify an emission location or a particular volume level for the 
signal, but encourages manufacturers, in the design of their systems, 
to consult available human factors guidelines for audio (and visual) 
characteristics of medical device alarms and signals (e.g., Ref. 1), 
and to test and evaluate their systems under representative operational 
conditions.
    3. One of the comments referred to the workshop on fluoroscopy 
discussed in comment 1 above, and noted a number of additional 
suggestions for changes to fluoroscopic x-ray system performance that 
were advocated by attendees at that workshop (Ref. 2).
    Those additional suggestions for changes are beyond the scope of 
the current proposal and would require a separate proposal and 
opportunity for comment. FDA agrees that the recommendations from the 
workshop should be considered as the basis for possible future 
amendments to the standard.

III. Environmental Impact

    The agency has determined under 21 CFR 25.24(e)(3) 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.

IV. Analysis of Impacts

     An analysis of the costs and benefits of this regulation, 
conducted under Executive Order 12291, was discussed in the proposed 
rule and the substance of that analysis has not changed. Executive 
Order 12291 has been superseded by Executive Order 12866. FDA has 
examined the impacts of this final rule under Executive Order 12866 and 
the Regulatory Flexibility Act (Pub. L. 96-354). 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 rule is consistent with the regulatory philosophy and principles 
identified in the Executive Order. In addition, the rule is not a 
significant regulatory action as defined by the Executive Order and so 
is not subject to review under the Executive Order.
     The Regulatory Flexibility Act requires agencies to analyze 
regulatory options that would minimize any significant impact of a rule 
on small entities. This amendment to the performance standard will 
affect the small fraction of fluoroscopic systems which are currently 
provided with high-level controls or which do not provide AERC, and 
have radiation outputs exceeding 1.29x10-3 C/kg per minute (5 R/
min). Further, the additional testing performed by x-ray manufacturers 
and government regulatory progams to ensure compliance with the 
performance standard, and the quality assurance testing performed by 
facilities can easily be included in current testing programs with 
minimal additional costs. The agency certifies that the rule will not 
have a significant economic impact on a substantial number of small 
entities. Therefore, under the Regulatory Flexibility Act, no further 
analysis is required.
     A copy of the threshold assessment supporting this determination 
is on file with the Dockets Management Branch (address above) and may 
be seen in that office between 9 a.m.and 4 p.m., Monday through Friday.

V. References

    The following references have been placed on display in the Dockets 
Management Branch (address above) and may be seen by interested persons 
from 9 a.m. to 4 p.m., Monday through Friday.
    1. ``Human Factors Engineering Guidelines and Preferred 
Practices for the Design of Medical Devices,'' AAMI HE48-R-93, 2d 
ed., Association for the Advancement of Medical Instrumentation, 
3330 Washington Blvd., suite 400, Arlington, VA 22201-4598, 1993.
    2. ``Proceedings of the ACR/FDA Workshop on Fluoroscopy,'' ACR, 
October 1992.

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, 21 CFR part 
1020 is 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: Secs. 501, 502, 515-520, 530-542, 701, 801 of the 
Federal Food, Drug, and Cosmetic Act (21 U.S.C. 351, 352, 360e-360j, 
360gg-360ss, 371, 381).

    2. Section 1020.30 is amended in paragraph (b) by alphabetically 
adding a new definition for ``Pulsed mode'' and by revising the 
definition for ``Source-image receptor distance'' to read as follows:


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

* * * * *
    (b) Definitions. * * *
* * * * *
    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.
* * * * *
    Source-image receptor distance (SID) means the distance from the 
source to the center of the input surface of the image receptor.
* * * * *
    3. Section 1020.32 is amended by revising paragraph (d), by 
redesignating paragraphs (e) through (h) as paragraphs (f) through (i), 
respectively, and by adding new paragraph (e) to read as follows:


Sec. 1020.32  Fluoroscopic equipment.

* * * * *
    (d) Entrance exposure rates. For fluoroscopic equipment 
manufactured before May 19, 1995, the following requirements apply:
    (1) Equipment with automatic exposure rate control (AERC). 
Fluoroscopic equipment that is provided with AERC shall not be operable 
at any combination of tube potential and current that will result in an 
exposure rate in excess of 2.58x10-3 coulomb per kilogram (C/kg) 
per minute (10 roentgens per minute (10 R/min)) at the point where the 
center of the useful beam enters the patient, except:
    (i) During recording of fluoroscopic images, or
    (ii) When an optional high-level control is provided. When so 
provided, the equipment shall not be operable at any combination of 
tube potential and current that will result in an exposure rate in 
excess of 1.29x10-3 C/kg per minute (5 R/min) at the point where 
the center of the useful beam enters the patient, 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) Equipment without AERC (manual mode). Fluoroscopic equipment 
that is not provided with AERC shall not be operable at any combination 
of tube potential and current that will result in an exposure rate in 
excess of 1.29x10-3 C/kg per minute (5 R/min) at the point where 
the center of the useful beam enters the patient, except:
    (i) During recording of fluoroscopic images, or
    (ii) When an optional 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.
    (3) Equipment with both an AERC mode and a manual mode. 
Fluoroscopic equipment that is 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 exposure rate in excess of 
2.58x10-3 C/kg per minute (10 R/min) in either mode at the point 
where the center of the useful beam enters the patient except:
    (i) During recording of fluoroscopic images, or
    (ii) When the mode or modes have an optional high-level control, in 
which case that mode or modes shall not be operable at any combination 
of tube potential and current that will result in an exposure rate in 
excess of 1.29x10-3 C/kg per minute (5 R/min) at the point where 
the center of the useful beam enters the patient, 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 is being employed.
    (4) 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 exposure rate shall 
be measured at 1 centimeter above the tabletop or cradle.
    (ii) If the source is above the x-ray table, the exposure rate 
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 exposure rate 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 imaging 
assembly.
    (iv) In a lateral type of fluoroscope, the exposure 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.
    (5) Exemptions. Fluoroscopic radiation therapy simulation systems 
are exempt from the requirements set forth in paragraph (d) of this 
section.
    (e) Entrance exposure rate limits. For fluoroscopic equipment 
manufactured on and after May 19, 1995, the following requirements 
apply:
    (1) Fluoroscopic equipment operable at any combination of tube 
potential and current that results in an exposure rate greater than 
1.29x10-3 C/kg per minute (5 R/min) at the point where the center 
of the useful beam enters the patient shall be equipped with AERC. 
Provision for manual selection of technique factors may be provided.
    (2) Fluoroscopic equipment shall not be operable at any combination 
of tube potential and current that will result in an exposure rate in 
excess of 2.58x10-3 C/kg per minute (10 R/min) at the point where 
the center of the useful beam enters the patient except:
    (i) 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.
    (ii) When an optional high-level control is activated. When the 
high-level control is activated, the equipment shall not be operable at 
any combination of tube potential and current that will result in an 
exposure rate in excess of 5.16x10-3 C/kg per minute (20 R/min) at 
the point where the center of the useful beam enters the patient. 
Special means of activation of high-level controls shall be required. 
The high-level control shall only be operable 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 (e) of this 
section shall be determined as follows:
    (i) If the source is below the x-ray table, the exposure rate shall 
be measured at 1 centimeter above the tabletop or cradle.
    (ii) If the source is above the x-ray table, the exposure rate 
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 exposure rate 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 lateral type of fluoroscope, the exposure 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 (e) of this 
section.
* * * * *

    Dated: May 12, 1994.
Michael R. Taylor,
Deputy Commissioner for Policy.
[FR Doc. 94-12155 Filed 5-17-94; 8:45 am]
BILLING CODE 4160-01-F