[Federal Register Volume 64, Number 127 (Friday, July 2, 1999)]
[Rules and Regulations]
[Pages 35924-35928]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-16835]
-----------------------------------------------------------------------
DEPARTMENT OF HEALTH AND HUMAN SERVICES
Food and Drug Administration
21 CFR Part 1020
[Docket No. 98N-0877]
Medical Devices; Performance Standard for Diagnostic X-Ray
Systems; Amendment
AGENCY: Food and Drug Administration, HHS.
ACTION: Final rule.
-----------------------------------------------------------------------
SUMMARY: The Food and Drug Administration (FDA) is issuing a final rule
that amends the diagnostic x-ray systems performance standard for
dental panoramic systems and mammography systems. This rule exempts
panoramic dental x-ray units from the requirement that they be
manufactured with exposure timers that automatically reset to zero upon
premature termination of an exposure. Removing the automatic timer
reset requirement will not compromise the quality of the radiographic
image and will protect patients from being subject to unnecessary
radiation due to repeat radiographs. This action also is intended to
align the performance standard for mammography systems with the
equipment requirements issued under the Mammography Quality Standards
Act of 1992 (the MQSA).
EFFECTIVE DATE: September 30, 1999.
FOR FURTHER INFORMATION CONTACT: Richard V. Kaczmarek, Center for
Devices and Radiological Health (HFZ-240), Food and Drug
Administration, 1350 Piccard Dr., Rockville, MD 20850, 301-594-0865.
SUPPLEMENTARY INFORMATION:
I. Background
A. Panoramic Dental Radiograph
The requirements in Sec. 1020.31 (21 CFR 1020.31) apply to
diagnostic x-ray systems, including those used for dental radiography
and mammography. Based on information from manufacturers, FDA had
determined that the timer requirement in Sec. 1020.31(a)(2)(i) should
not apply to panoramic dental units. As a result of that determination,
FDA exercised its enforcement discretion and did not apply the timer
requirement to panoramic dental units. Some States had adopted local
standards that were identical in language to FDA's regulation, but did
not exempt panoramic dental units from the timer requirement because
those units were not expressly exempted in the Federal regulation.
Those States were applying the timer requirement to dental panoramic
units. To correct this inconsistency, FDA has amended the regulations
to expressly exempt panoramic dental units from the timer requirement
in Sec. 1020.31(a)(2)(i). This change should lead to consistency among
government requirements.
B. Mammography X-Ray Devices
The recent passage of the MQSA (Pub. L. 102-539) and issuance of
the interim and final MQSA regulations have focussed attention on the
mammography equipment requirements contained in 21 CFR part 1020.
Although the MQSA is directed to facility requirements for maintaining
mammography quality, both the interim and the final MQSA regulations
address x-ray equipment that is also subject to the performance
standard for diagnostic x-ray systems (58 FR 67558 and 58 FR 67565,
December 21, 1993; and 62 FR 55976, October 28, 1997). The MQSA and
FDA's regulations governing mammography establish quality standards for
facilities performing mammography to ensure safe, reliable, and
accurate mammography nationwide. FDA wanted to ensure that the
standards applying to radiation emitting electronic products, including
mammography equipment, and those applying to the facilities that use
such equipment were in accord. To bring the standards into harmony, FDA
has amended its performance standard for diagnostic x-ray systems.
The MQSA standards also address the proper viewing of mammography
films. The standard practice is that these films be read on view boxes
(light boxes) with the ambient room light levels reduced. Unexposed
film areas and parts of the light box not covered by exposed film
should be masked to prevent the bright light surrounding the radiograph
from interfering with reading the film.
Extending the x-ray field to expose the borders of the film
simplifies the work of the radiologist and accreditation bodies because
they have to create only one mask size, rather than having to create
individualized masks for each facility. With the current practice being
to irradiate the same area of the same sized film for all patients,
there is little evidence that allowing the x-ray field to completely
darken the film will significantly raise the radiation safety risk to
the patient. FDA has amended the diagnostic x-ray systems standard to
allow fixed aperture and variable aperture beam-limiting device (BLD)
systems, to open up or adjust the field size to cover the entire film
and thus reduce the need to provide a different mask for each film. In
certain instances, limiting the x-ray field to the size of the breast
may be considered to be advantageous. Practitioners still retain this
option, which may result in improved imaging quality due to the
reduction of scattered radiation.
To reduce unnecessary radiation exposure to the patient beyond the
plane of the image receptor, FDA has requirements for x-ray field
limitation and alignment. In the past, all systems in use for
mammography had fixed aperture plates for x-ray field limitation. The
advent of the variable aperture BLD for mammography is potentially a
problem with respect to the primary barrier requirement if a BLD is
opened so that the useful beam extends beyond the primary barrier
provided by the image receptor support device. To prevent this problem,
a variable aperture BLD must provide some restriction on the maximum
field size to ensure that the entire useful beam at the plane of the
image receptor is contained within the image receptor support device,
which is also a primary barrier. In other words, for a fixed aperture
or a variable aperture BLD with the collimator opened as wide as
possible, the entire useful beam should not extend beyond the barrier,
at any available source-image receptor distance (SID), except at the
chest wall side, and the exposure level 5 centimeters beyond this
barrier should not exceed 2.58X10-8 coulombs per kilogram
(C/k) (0.1 milliroentgen (mR)) per exposure. This requirement is in
agreement with the International Electrotechnical Commission (IEC)
draft standard for mammography systems (IEC 62B/60601-2-45).
II. The Final Rule
FDA believes that the final rule establishes reasonable
requirements that can be implemented by the regulated industry without
unnecessary burden. None of the comments on the proposed rule requested
that FDA revise any of the changes proposed.
A. Panoramic Dental Radiograph
The final rule exempts panoramic dental x-ray units from the
requirement in Sec. 1020.31(a)(2)(i) that they be
[[Page 35925]]
manufactured with exposure timers that automatically reset to zero upon
premature termination of an exposure. This change incorporates into
regulation current FDA policy and should lead to consistency among
Federal, State, and local requirements.
B. Mammography X-Ray Devices
The MQSA requires that only x-ray equipment specifically designed
for mammography can be used for mammography. Therefore, FDA has removed
the reference in Sec. 1020.31(f)(3), which allowed the use of general
purpose x-ray equipment with special attachments for mammography. This
change harmonizes this regulation with the MQSA equipment requirements.
Section 1020.31 permits the x-ray irradiation field at the plane of
the image receptor to extend to the edges of the x-ray film. However,
to protect the patient from unnecessary exposure to radiation, the
mammographic field alignment requirement restricts the irradiation beam
from extending beyond the edge of the receptor by no more than 2
percent of the SID. The limit on x-ray transmission through the primary
barrier (except on the chest wall edge) remains unchanged. FDA has
added the words ``for transmission'' to Sec. 1020.31(m)(4) to further
clarify the section.
The definition for ``image receptor support device'' replaces the
definition of ``image receptor support'' and clarifies that image
receptor support devices must provide a primary protective barrier for
any orientation of the x-ray tube and the image receptor support device
(except the chest wall side). This revision maintains the requirement
in the current Sec. 1020.31(m) that the image receptor support device
must serve to provide a primary protective barrier that intercepts the
useful beam. Equipment manufactured prior to the effective date of this
rule has always been, and will continue to be, subject to the
requirement that the primary barrier must intercept the useful beam.
Unlike fixed aperture systems, which meet the established primary
barrier requirement, with variable aperture collimation there is the
possibility that the dimensions of the x-ray beam may be adjusted to
exceed the area of the image receptor. This requirement confines the x-
ray beam to the dimensions of the primary barrier provided by the image
receptor support device, except on the chest wall side.
FDA has clarified the requirement that patient exposures not be
permitted without an appropriate primary barrier in place, by stating
the requirement explicitly. FDA further clarifies the requirement by
adding the word appropriate prior to primary barrier. FDA wants to
clarify that it is not appropriate for a mammographic x-ray system to
generate x-rays with an inappropriate image receptor support device in
place. To reduce radiation exposure to the patient, the rule provides
that the image receptor support device, acting as the primary barrier,
must be in place before a mammographic x-ray system can generate x-
rays. This requirement requires the image receptor support device be
interlocked with the system so that an exposure cannot be made with the
image receptor support device removed.
C. Effective Date
This rule will be effective in 90 days. Usually, amendments to
performance standards for electronic products become effective 1 year
after the date of publication of the final rule to allow sufficient
time for manufacturers to implement the changes in design or production
practices (21 U.S.C. 360kk(c)). In the proposed rule, FDA explained its
good cause basis for proposing a shorter timeframe, namely that the
amendments were codifying current industry practice, making regulatory
requirements consistent, or relaxing requirements, and requested
comments on the proposed shortening of the timeframe. No comments were
received. Consequently, this rule becomes effective September 30, 1999.
III. The Proposed Rule
In the Federal Register of October 29, 1998 (63 FR 57957), FDA
published a proposed rule to amend the performance standard for
diagnostic x-ray systems (dental and mammographic systems
requirements). The proposed rule contained the reasons for the proposed
amendment, summarized the Technical Electronic Product Radiation Safety
Standards Committee's recommendation regarding dental and mammographic
systems, and delineated the statutory authority under which FDA issues
this rule. The proposed rule also stated FDA's grounds showing good
cause for prescribing an earlier effective date than 1 year after the
date of publication of the final rule for these amendments to the
performance standard and solicited specific comment on the timeframe
for implementation of the final rule. Written comments were due January
27, 1999.
FDA received three comments, one each from a manufacturer, a
professional society, and a State agency. All three comments supported
the actions proposed in the rule. None of the comments commented on the
timeframe for implementation of the final rule.
IV. Response to Comments
All three comments supported the actions proposed in the rule. One
of the comments requested clarification concerning Sec. 1020.31(m)(2),
which would require that the x-ray tube shall not permit exposure
unless the barrier is in place to intercept the useful beam. The
concern was whether the manufacturer would be held responsible if an
individual equipment owner chose to partially dismantle the system or
bypass interlocks so that the x-ray tube could be operated with the
primary barrier removed. The comment stated that such action would
violate Sec. 1020.30(q)(2), which prohibits the owner of the equipment
from modifying the equipment such that it would no longer comply with
Sec. 1020.31. In such a case, the comment argued that FDA should cite
the owner, not the manufacturer, for noncompliance.
FDA agrees that a manufacturer should not be held responsible
should an owner circumvent the interlocks to operate the system with
the primary barrier removed. The regulation does not require the
manufacturer to design an interlock that cannot be defeated. A
modification by the owner that makes the unit noncompliant with
Secs. 1020.31(m)(2) and 1020.30(q) may cause the device to be
misbranded and adulterated. FDA could bring an action against the
person who caused the misbranding and adulteration and also seek to
enjoin use of the device.
None of the comments include any recommendations on the timeframe
for implementation of the final rule or suggest that FDA does not have
good cause for shortening the customary 1-year period. FDA believes
that unneeded delay in the implementation of these amendments could
lead to difficulties for mammography facilities because of confusion
over the requirements of the x-ray performance standard and standards
issued under the MQSA. In addition, because the amendments clarify a
provision of the Federal standard, FDA believes it is in the best
interests of patients, facilities, and manufacturers to implement the
dental x-ray equipment amendment expeditiously. For these reasons, the
effective date of the final rule will be 90 days after date of
publication in the Federal Register.
V. Environmental Impact
The agency has determined under 21 CFR 25.30(a) and (i) and
25.34(c) that
[[Page 35926]]
this action is of a type that does not individually or cumulatively
have a significant effect on the human environment. Therefore, neither
an environmental assessment nor an environmental impact statement is
required.
VI. Analysis of Impacts
FDA has examined the impact of this final rule under Executive
Order 12866 and the Regulatory Flexibility Act (5 U.S.C. 601-612) (as
amended by subtitle D of the Small Business Regulatory Fairness Act of
1996 (Pub. L. 104-121)), and the Unfunded Mandates Reform Act of 1995
(Pub. L. 104-4). Executive Order 12866 directs agencies to assess all
costs and benefits of available regulatory alternatives and, when
regulation is necessary, to select regulatory approaches that maximize
net benefits (including potential economic, environmental, public
health and safety, and other advantages; distributive impacts; and
equity). The agency believes this final rule is consistent with the
regulatory philosophy and principles identified in the Executive Order.
In addition, the final rule is not a significant regulatory action as
defined by the Executive Order and therefore 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. Because this final rule increases the flexibility of
the performance standard and codifies current interpretations of
Federal regulations in order to prevent inconsistent interpretations by
State and local governments, and because none of the domestic
manufacturers of panoramic dental units or mammography x-ray systems
would be considered small entities, the agency certifies that the final
rule will not have a significant economic impact on a substantial
number of small entities engaged in manufacturing. Because dental and
mammography facilities will buy machines with the changes to the
performance standard allowed in this final rule only if it is
economically advantageous to do so, the agency certifies that the final
rule will not have a significant economic impact on a substantial
number of small entities that are facilities (most, if not all, of
which would be considered small entities). Therefore, under the
Regulatory Flexibility Act, no further analysis is required.
In the proposed rule, FDA conducted and published an initial
regulatory flexibility analysis to ensure that impacts on small
entities were assessed and to alert any potentially impacted entities
to the opportunity to submit comments to this agency. No comments on
the initial regulatory flexibility analysis were submitted. This final
rule will not impose costs of $100 million or more in either the
private sector or State, local, and tribal governments in the
aggregate. Consequently, a summary statement of analysis under section
202(a) of the Unfunded Mandates Reform Act of 1995 is not required.
In part, the final rule codifies the equipment performance
standards established under the MQSA by requiring only x-ray systems
designed specifically for mammography be marketed for mammography. This
rule updates the x-ray performance standard to reflect a standard
already enforced under the MQSA. Consequently, FDA expects no economic
impact from this portion of the final rule.
The final rule also permits the x-ray irradiation field to extend
to the edges of the x-ray film but not beyond the primary barrier
provided by the image receptor support device. It further changes the
definition of an image receptor support device, clarifying that it must
provide a primary protective barrier and that exposures not be possible
without the image receptor support device being in place, acting as the
primary barrier. Exposing all of the film allows one size of film mask
to be used for proper viewing of mammography films using light boxes
and prohibiting extension of the beam beyond the primary barrier
protects the patient from unnecessary exposure to radiation. The
amendment to relax the field edge alignment criteria will not require
any changes to x-ray mammography systems that are currently compliant;
these systems will remain compliant after the effective date. The
amendment will, however, allow the user to modify or purchase a
collimator that has the ability to provide films without light borders
as a convenience in simplifying viewing conditions. FDA believes that
most of the image receptor support devices that are currently in use
meet the requirements in the amendments to Secs. 1020.30(b) and
1020.31(m). In addition, when the manufacturer's design of the cassette
holder provides the primary barrier attenuation itself, then the
cassette holder is considered a part of the image receptor support
device. Therefore, FDA estimates that the amendments to
Secs. 1020.30(b) and 1020.31(m) will impose minimal new costs. This
rule also allows more flexibility for mammography facilities and
accreditation bodies without compromising the public health and may
reduce costs to mammography facilities and accreditation bodies by
simplifying the masking of images.
The final rule exempts panoramic x-ray dental units from the
requirement that they be manufactured with exposure timers that
automatically reset to zero or the initial setting upon premature
termination of an exposure. For panoramic dental exposures,
interrupting the exposure does not affect the quality of images already
taken. Consequently, restarting the exposure at the initial starting
point exposes patients to unnecessary radiation. This rule removes a
regulatory requirement, while still protecting the public health, and
may reduce costs to dental facilities and patients. FDA has identified
no new reporting, recordkeeping, or other compliance requirements
associated with this rule.
The Safe Medical Devices Act of 1990 (Pub. L. 101-629) enacted on
November 28, 1990, transferred the provisions of the Radiation Control
for Health and Safety Act of 1968 (Pub. L. 90-602) from Title III of
the Public Health Service Act (42 U.S.C. 201 et seq.) to Chapter V of
the Federal Food, Drug, and Cosmetic Act (21 U.S.C. 201 et seq.). These
provisions regulate electronic products that emit radiation. On October
27, 1992, the MQSA was enacted to establish uniform, national quality
standards for mammography. The MQSA (42 U.S.C. 263b(f)(1)(B)) requires
the use of radiological equipment specifically designed for mammography
to be used for mammography. Similarly, 21 CFR 900.12(b)(1) of the
interim and final mammography regulations prohibits the use of
conventional radiographic equipment for mammography.
There are approximately 10,000 mammography facilities in the United
States. Because this change in the performance standard only applies to
components manufactured after the effective date of the final rule, the
associated cost does not apply to those machines manufactured prior to
that date. FDA estimates that approximately 10 percent of facilities
replace their mammography machines in any one year. At this time, FDA
is unable to estimate the demand for the modifications to systems
currently in use. As discussed previously, the change concerning x-ray
beam collimation is less restrictive than the present standard. FDA
estimates the cost per system to be between $0 and $5,000, if the
system modification is made during production.
There are approximately 138,500 dental facilities in the United
States of
[[Page 35927]]
which 40 percent provide access to panoramic dental x-ray units. An
uncertain number of these facilities may request the manufacturer to
remove the automatic reset of the exposure timer on their panoramic
machines; however, they are not required to do so. FDA believes that
the facility will only make this change if it is economically or
clinically advantageous to do so. FDA estimates it will cost a facility
an amount equal to what would be assessed for a routine service call
(approximately $150.00 or less) to remove the automatic reset function
for premature termination of an exposure for existing systems. FDA
believes that manufacturers no longer manufacture panoramic dental x-
ray units with automatic reset exposure times.
Most, if not all, of the mammography facilities and dental
facilities would be considered small under the criteria establishment
by the Small Business Administration. FDA's registration system shows
five manufacturers of panoramic dental units. Of the domestic
manufacturers, none would be considered small entities. There are
approximately 10 manufacturers of mammography x-ray systems. Of these
manufacturers, none would be considered small entities.
For the mandatory changes to image receptor support devices, FDA
believes that most of the image receptor support devices that are
currently in use provide a primary barrier that is capable of meeting
the requirements in the amendments to Secs. 1020.30(b) and 1020.31(m).
There are approximately 10,000 mammography facilities in the United
States. Because this change in the performance standard only applies to
systems manufactured after the effective date of a final rule, the
costs associated with any changes that may need to be made, would not
apply to those machines manufactured prior to that date. FDA estimates
that approximately 10 percent of facilities replace their mammography
systems in any one year (10 percent of 10,000 = 1,000). FDA estimates
the cost per system to be between $0 and $2,000 in the event that any
manufacturers are required to implement design or production changes to
ensure that exposures not be permitted on their systems without a
primary barrier being in place. FDA estimates approximately 95 percent
of systems currently being marketed already meet this requirement. With
an annual mammography system replacement rate of 10 percent (i.e.,
1,000 new systems purchased per year), FDA estimates only approximately
5 percent of these 1,000 systems may increase the cost to meet the
requirement. To calculate the annual cost, FDA estimates a cost of $0
to $2,000 per system multiplied by 50 systems (5 percent of 1,000 =
50). Using this estimate, the costs are expected to be approximately $0
to $100,000.
Under these changes to the performance standard, FDA allows
manufacturers and facilities to decide whether to implement any device
modifications in response to the greater flexibility in these
mammography collimation requirements. If the benefits associated with
the flexibility in this rulemaking are outweighed by the costs to the
facility, the facility can choose to not purchase a device that has
been modified in response to the greater flexibility in this
rulemaking. With regard to the mandatory change, FDA believes that the
great majority of the image receptor support devices that are currently
being manufactured provide a primary barrier that is capable of meeting
the requirements in the amendment to Sec. 1020.31(m). Therefore, FDA
does not anticipate that the amendment to Sec. 1020.31(m) will impose
any significant costs.
Because most of these changes to the mammography performance
standard and the change to the timer requirement for panoramic dental
systems do not increase regulatory burdens, FDA considered no
alternatives to accomplish the stated objectives of the applicable
statutes. For the primary barrier standard in Sec. 1020.31(m), FDA
considered not requiring the primary barrier to be in place to
intercept the useful beam. This alternative was rejected because
without the primary barrier in place, patients would be exposed to
unnecessary radiation.
VII. Paperwork Reduction Act of 1995
This final rule contains no collections of information. Therefore,
clearance by the Office of Management and Budget under the Paperwork
Reduction Act of 1995 is not required.
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: 21 U.S.C. 351, 352, 360e-360j, 360gg-360ss, 371, 381.
2. Section 1020.30 is amended in paragraph (b) by removing the
definition of ``image receptor support'' and adding a new definition in
alphabetical order to read as follows:
Sec. 1020.30 Diagnostic x-ray systems and their major components.
* * * * *
(b) * * *
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.
* * * * *
3. Section 1020.31 is amended by revising paragraphs (a)(2)(i),
(f)(3), and (m) to read as follows:
Sec. 1020.31 Radiographic equipment.
* * * * *
(a) * * *
(2) * * *
(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.
* * * * *
(f) * * *
(3) Systems designed for mammography. (i) Mammographic beam-
limiting devices manufactured after 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 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.
(ii) Each image receptor support device intended for installation
on a system designed for mammography shall have clear and permanent
markings to indicate the maximum image receptor size for which it is
designed.
* * * * *
[[Page 35928]]
(m) Primary protective barrier for mammography x-ray systems. For
mammography x-ray systems manufactured after September 30, 1999:
(1) 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.
(2) The x-ray tube shall not permit exposure unless the appropriate
barrier is in place to intercept the useful beam as required in
paragraph (m)(1) of this section.
(3) The transmission of the useful beam through the primary
protective barrier shall be limited such that the exposure 5
centimeters from any accessible surface beyond the plane of the primary
protective barrier does not exceed 2.58X10-8 C/kg (0.1 mR)
for each activation of the tube.
(4) Compliance 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.
Dated: June 16, 1999.
Margaret M. Dotzel,
Acting Associate Commissioner for Policy Coordination.
[FR Doc. 99-16835 Filed 7-1-99; 8:45 am]
BILLING CODE 4160-01-F