[Federal Register: October 29, 1998 (Volume 63, Number 209)]
[Proposed Rules]
[Page 57957-57963]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr29oc98-22]
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DEPARTMENT OF HEALTH AND HUMAN SERVICES
Food and Drug Administration
21 CFR Part 1020
[Docket No. 98N-0877]
Medical Devices; Performance Standards for Dental and
Mammographic X-Ray Devices; Amendment
AGENCY: Food and Drug Administration, HHS.
ACTION: Proposed rule.
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SUMMARY: The Food and Drug Administration (FDA) is proposing to exempt
panoramic dental x-ray units from the requirement that they be
manufactured with exposure timers which 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 subjected to unnecessary
radiation due to repeat radiographs. FDA also proposes five changes to
align the performance standard with the
[[Page 57958]]
equipment requirements issued under the Mammography Quality Standards
Act of 1992 (MQSA). First, the agency proposes to remove any reference
to the use of equipment not specifically designed for mammography from
the performance requirements for mammography equipment. Second, FDA
proposes that the mammographic field alignment requirements restrict
the irradiation beam to less than 2 percent of the source-image
receptor distance (SID) beyond the image receptor edges. Third, it is
proposed that the definition of an image receptor support device be
amended to specify that it must provide a primary protective barrier
for any orientation of the x-ray tube and image receptor support device
assembly. Fourth, it is proposed that the useful beam must be confined
to the dimensions of the primary barrier provided by the image receptor
support device (except on the chest wall side). Fifth, it is proposed
that exposures not be permitted without the primary barrier in place.
DATES: Written comments by January 27, 1999.
ADDRESSES: Submit written comments to the Dockets Management Branch
(HFA-305), Food and Drug Administration, 5630 Fishers Lane, rm. 1061,
Rockville, MD 20852.
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
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 (PHS Act) to Chapter V of the Federal
Food, Drug, and Cosmetic Act (the act). Under the act (21 U.S.C. 301 et
seq.), FDA is proposing to amend the performance standard for
diagnostic x-ray systems and their major components. Performance
Standards for Ionizing Radiation Emitting Products are contained in
part 1020 (21 CFR part 1020). This standard was initially published in
the Federal Register of August 15, 1972 (37 FR 16461). Since that time
there have been several amendments, both to stay current with
technological developments and to clarify the interpretation of the
provisions. Additionally, the President's Radiation Protection Guidance
to Federal Agencies for Diagnostic X-Rays, published on February 1,
1978 (43 FR 4377), recommended that the fundamental objective in
performing x-ray examinations should be to obtain optimum diagnostic
information with minimum patient exposure.
The radiographic equipment standards of Sec. 1020.31 apply to
diagnostic x-ray systems, including those used for dental radiography
and mammography. The most recent amendments to the performance
standard, published in the Federal Register of May 3, 1993 (58 FR
26386), and corrected May 28, 1993 (58 FR 31067), and May 19, 1994 (59
FR 26402), did not affect the timer requirements for dental systems or
the x-ray beam limitation on mammography systems. Most recently, the
passage of the MQSA (Pub. L. 102-539) and issuance of interim and final
MQSA regulations have focussed attention on the mammography equipment
requirements contained in part 1020. Although the MQSA is directed to
facility requirements for maintaining mammography quality, both the
interim and the final MQSA regulations contain certain requirements for
mammographic x-ray equipment that is also subject to the performance
standard for diagnostic x-ray systems (58 FR 67558, 58 FR 67565, and 62
FR 55976).
The safety and performance aspects of panoramic dental systems were
discussed with the Technical Electronic Product Radiation Safety
Standards Committee (TEPRSSC) in 1996. TEPRSSC is a statutory advisory
committee (21 U.S.C. 360kk(f)(1)(A)) that FDA is required to consult
prior to proposing any electronic product performance standards under
the act. TEPRSSC recommended that the performance standard be amended
to exempt panoramic systems from the timer reset requirement. The
issues of collimation of the mammography x-ray field and primary
barrier transmission were presented and discussed with TEPRSSC at the
1997 meeting. The recommendation was that FDA amend the performance
standard for diagnostic x-ray systems to allow the dimensions of the x-
ray beam to exceed the image receptor dimensions by up to 2 percent of
the SID, and that the beam be fully intercepted by the image receptor
support device, except on the chest wall side. TEPRSSC also recommended
that the primary barrier transmission requirement be retained, that
manufacturers discontinue the practice of designing general purpose x-
ray systems so that they may be used to perform mammography, and that
manufacturers not promote or encourage their use for mammography. FDA
has reviewed the recommendations of TEPRSSC and agrees with their
recommendations. Accordingly, FDA is proposing to amend the performance
standard as indicated as follows.
Amendments to performance standards for electronic products
ordinarily become effective 1 year after the date of publication of the
final rule to allow sufficient time for manufacturers to implement
changes in design or production practices (21 U.S.C. 360kk(c)). FDA
believes it would have good cause for prescribing an earlier effective
date for these proposed mammography amendments, as unneeded delay in
their implementation could lead to difficulties for mammography
facilities because of confusion about the requirements of different
government standards when the MQSA final regulations become effective
in April 1999. FDA also feels that an unneeded delay in the final
dental x-ray amendments could lead to problems for dental facilities.
Because this proposed amendment clarifies a provision of the Federal
standards, FDA believes that it will prevent misunderstandings by State
regulators. FDA welcomes comments on the timeframe for implementation
of a final rule.
II. Dental X-Ray Devices
A. Panoramic Dental Radiography
FDA established the requirement that exposure timers be
automatically reset upon premature termination of an exposure because
the agency believed that the resulting radiograph would not provide
adequate diagnostic information because of insufficient exposure of the
film. Further, it was felt that the continuation of the exposure was
not advisable because any patient movement occurring for any reason
would make it impossible to obtain an adequate diagnostic image. The
rationale was that discontinuing exposure would ensure that the patient
did not receive exposure to x-rays that was unnecessary since it would
not produce a clinically useful radiograph. The requirement that the
timer automatically be reset results in a repeat exposure from the
start in order to achieve adequate radiographic quality.
In 1974, FDA determined through correspondence with a manufacturer
of panoramic dental units that the timer requirement of
Sec. 1020.31(a)(2)(i) should not apply to the manufacturer's units. The
manufacturer's units performed a panoramic sweep in 9 to 12 seconds.
However, if the system were stopped, it could resume the panoramic
examination starting from where it was
[[Page 57959]]
interrupted, and viable image data would still be obtained without the
need to restart the panoramic view. This resumption was because of the
design of the system and the manner in which the image was acquired. As
the tube head of a panoramic system moves, so does the film, resulting
in only a small portion of the film being irradiated at a given
interval of time. A lead shield protects the unexposed and previously
exposed parts of the film. Therefore, stopping and restarting of the
exposure did not result in a radiograph which was unusable.
FDA notified the manufacturer that the panoramic dental unit would
not be considered noncompliant with the performance standard of
Sec. 1020.31(a)(2)(i) and FDA has followed this interpretation for
other panoramic dental units that perform in a similar manner since
then.
B. Interpretations of the Performance Standard
Although the agency has exercised its discretion in not enforcing
the timer requirement against manufacturers of panoramic dental units,
FDA believes it is necessary to expressly exempt such units from the
timer reset requirement. Section 542 of the act (21 U.S.C. 360ss)
provides that any State or local standard applicable to the same aspect
of performance as the Federal performance standard must be identical to
the Federal standard. State and local officials in jurisdictions that
have adopted requirements identical to Sec. 1020.31(a)(2)(i) may
enforce that requirement against manufacturers of panoramic dental
units. Thus, to ensure consistency among Federal, State, and local
requirements, FDA believes a change to the performance standard is
necessary.
III. Mammography X-Ray Devices
A. Equipment Requirements and the Mammography Quality Standards Act
The MQSA and FDA's regulations governing mammography establish
quality standards for facilities performing mammography to assure safe,
reliable, and accurate mammography nationwide. FDA would like to ensure
that the standards pertaining to radiation emitting electronic
products, including mammography equipment, and those pertaining to the
facilities that use such equipment are in accord. Presently, the
equipment standard specifies that the x-ray field must be contained
within the borders of the image receptor, except on the chest wall side
(Sec. 1020.31(f)(3)). The equipment standard also indicates a limit on
the maximum allowable transmission through the image receptor support
device. FDA proposes to modify the field alignment requirements to
allow the x-ray field to extend beyond any edge of the image receptor
in such a manner that this extension does not exceed 2 percent of the
SID. The limit on x-ray transmission through the image receptor support
would still apply except on the chest wall edge.
The MQSA requires that only equipment specifically designed for
mammography can be used by facilities. Systems designed for other types
of studies but provided with special attachments for mammography are no
longer allowed under MQSA. As a result, it is proposed that
Sec. 1020.31(f)(3) be changed to be consistent with the MQSA
requirements by deleting the language which previously included general
purpose radiographic systems.
B. Field Size Limitations
Section 1020.31(f)(3) pertains to field limitation of mammographic
x-ray equipment. It states that:
[R]adiographic systems designed only for mammography and general
purpose radiographic systems, when special attachments for
mammography are in service, 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.
The previous requirement holds the manufacturer or assembler of the
equipment (not the facility) responsible for providing means to limit
the x-ray field at the image receptor plane so that the x-ray field
does not extend beyond any edge of the image receptor except the side
adjacent to the chest wall. FDA's standard also defines the image
receptor as a fluorescent screen, radiographic film, 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.
The image receptor is the film itself (where film is used). In this
case, neither the image receptor assembly nor the cassette holder is
considered the image receptor. For fixed aperture devices, in order to
assure that the x-ray field does not exceed the edges of the image
receptor, the manufacturer must restrict the beam so that unexposed
edges will appear on the developed film to account for film size
tolerances or shifts inside the cassette. For stepless adjustable beam-
limiting devices (BLD), the means provided by the manufacturer to
assure compliance with the previous requirement is that the x-ray field
must always be slightly smaller than the light field. Thus, when the
operator adjusts the light field to the image receptor size, the x-ray
field will indeed be contained within the borders of the image receptor
(except of course on the side adjacent to the chest wall which is
allowed a tolerance of up to 2 percent of the SID). For this type of
BLD, the operator may also open the field to any size and is limited
only by the maximum opening allowed by the system which should be
restricted by the limits established by Sec. 1020.31(m).
One aspect of the MQSA requirements addresses the proper viewing of
mammography films. The standard practice is that these be read on view
boxes (light boxes) with the ambient room light levels reduced.
Unexposed film areas and parts of the light box should be masked to
prevent the bright light surrounding the radiograph from interfering
with the interpretation under these conditions. It is possible to
tailor the masking of these areas for individual cases; however, this
becomes a problem when large numbers of films are viewed, as in a
breast screening program. The work of the radiologist is expedited if
radiographs are produced without transparent margins. Another
consideration is that the clinical image review process of
accreditation bodies, such as the American College of Radiology, is
simplified by having to create only one mask size, rather than having
to create individualized masks for each facility. A practice used by
some facilities with variable aperture BLD is to increase the x-ray
field size to expose the borders of the film and thus reduce the need
to provide a different mask for each film. However, fixed aperture
systems cannot open up or adjust the field size to cover the entire
film to eliminate the unexposed borders. The radiation safety concept
of collimating the x-ray beam to the body region of interest is valid
in mammography, but it is of little relevance since the breast is
normally completely irradiated. There is little evidence that changing
the x-ray field coverage from just inside the edges of the film to just
outside the edges of the film would make a clinically significant
difference in image quality or significantly raise the radiation safety
risk to either the patient or the equipment operator.
Adoption of the 2 percent tolerance would bring FDA into
harmonization with the International Electrotechnical Commission (IEC)
equipment standard. The IEC has developed a draft standard
[[Page 57960]]
which addresses the requirements for the safety of mammographic x-ray
equipment and mammographic stereotactic devices (IEC 62B/60601-2-45).
Included in this document is a requirement that the x-ray field not
exceed the dimensions of the image receptor by more than 2 percent of
the source-image receptor distance, in agreement with what FDA is
herein proposing. In the rationale given for this decision, the IEC
included a discussion of currently accepted clinical practice that
involves irradiating the same field size area for all patients, which
in most cases substantially overlaps the actual region of interest. The
increasing use of brighter view boxes and radiographs of higher optical
densities is also mentioned, along with the importance of eliminating
view box glare at the film edges. Balancing this against the basic
radiation safety guidance of irradiating only the area of interest, the
IEC concluded that, in this case, any potential increase in patient
dose was justified by the overall benefit to the population being
screened.
With variable aperture collimation there is no control over how
much the x-ray beam can exceed the image receptor since the operator
can adjust the field larger. However, the field should not be larger
than the image receptor supporting device to prevent primary beam
irradiation of other parts of the body.
Manufacturers of mammographic equipment have requested that FDA
address the confusion between the requirements of the x-ray performance
standards and the MQSA. FDA is not requiring that the x-ray field must
exceed the area of the x-ray film. Rather, FDA is providing flexibility
by allowing the manufacturers to design their equipment so that the x-
ray field may be used to darken the film to its borders if desired by
the purchaser. Whether the film has borders or is darkened to the
edges, proper masking of the film for viewing is still needed for best
viewing results.
C. X-ray Transmission Through Primary Barrier
In addition to the requirements for x-ray field limitation and
alignment for mammography, requirements for primary beam transmission
became effective on September 5, 1978. The current requirement,
Sec. 1020.31(m), states that:
[F]or x-ray systems manufactured after September 5, 1978, 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 exposure 5 centimeters from any
accessible surface beyond the plane of the image receptor supporting
device does not exceed 2.58x10-8 C/kg (0.1 mR) for each
activation of the tube.
The intent of this requirement is to provide radiation safety for
the patient beyond the plane of the image receptor. Based on the
restrictions described in Sec. 1020.31(m) and the accompanying
preamble, it is clear that the intent of the image receptor supporting
device (IRSD) requirement was to reduce irradiation beyond the plane of
the image receptor or the IRSD which could strike the patient. Thus,
primary irradiation must be blocked and reduced for any accessible area
5 centimeters (cm) beyond the image plane. It is understood that for
the chest wall side some primary beam irradiation would not be blocked
by the IRSD and this is allowed in order to obtain as much diagnostic
information from the chest wall side of the breast as possible. Since
all of the primary beam (except on the chest wall side) should be
intercepted by the IRSD, a measurement only need be made of the
transmitted beam and at the shortest SID which would yield the largest
transmission reading. While it may be safe to allow the x-ray field to
exceed the image receptor by a certain amount, and necessary in order
to adequately image the breast tissue anatomy in the chest wall area,
there is no adequate justification for allowing the primary beam to
extend beyond the primary barrier provided by the IRSD except at the
chest wall side.
An additional problem arises for those manufacturers who use their
cassette as the image receptor support device and have placed
attenuating material on the bottom of the cassette in order to meet the
transmission requirements. Should the edge alignment requirements be
increased by amendment, these manufacturers would need to add an
additional barrier to their system or continue to restrict the beam to
prevent unattenuated primary beam beyond the plane of the IRSD. FDA
feels that the definition of an image receptor support which appears in
Sec. 1020.30(b) should be changed to indicate that the support device
must provide a primary protective barrier. This should apply for any
orientation of the x-ray tube and image receptor support device
assembly, not just in the horizontal plane as it currently states.
Furthermore, exposures should not be possible without the image
receptor support device, acting as the primary barrier, being in place.
The primary barrier transmission requirement is an absolute
restriction. The limit specified leaves the manufacturer free to choose
the method to reduce the x-ray transmission so that it does not exceed
2.58 x10-8 coulombs (C) per kilogram (kg) (0.1 milliroentgen
(mR)) per exposure. The image receptor support device must intercept
all of the primary beam (except the chest wall side) and reduce the
transmitted radiation to what is considered safe and feasible. Any
changes in the field sizing should ensure adherence to the transmission
requirements. In the past, all systems in use for mammography had fixed
aperture plates for x-ray field determination. The advent of the
variable aperture BLD for mammography is potentially a problem if a
beam-limiting device is opened so that primary x-rays extend beyond the
primary barrier provided by the image receptor support device. In order
to prevent this, a variable aperture BLD must provide some restriction
on the maximum field size to ensure that the primary beam is contained
within the IRSD which is also a primary barrier. In other words, with
the collimator opened as wide as possible, primary x-radiation should
not extend beyond the barrier, at any available SID, except at the
chest wall side, and the exposure level 5 cm beyond this barrier should
be less than the exposure value given previously.
FDA's position on primary barrier transmission is in agreement with
that taken by the IEC. Their draft standard on safety requirements for
mammography systems (62B/60601-2-45) requires primary barrier shielding
to extend at least to the projection of the patient support at the
chest wall side, and to extend at least 1 percent of the SID beyond the
x-ray field at the other sides.
IV. Environmental Impact
The agency has determined under 21 CFR 25.30(a) and (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. Comments
Interested persons may, on or before January 27, 1999, submit to
the Dockets Management Branch (address above) written comments
regarding this proposal. Two copies of any 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 office above
between 9 a.m. and 4 p.m., Monday through Friday.
[[Page 57961]]
VI. Analysis of Impacts
FDA has examined the impact of this proposed 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 that this proposed rule is consistent with
the regulatory philosophy and principles identified in the Executive
Order. In addition, the proposed 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. An analysis of available information suggests that
costs to the entities most affected by this rule, including small
entities, are not expected to be significant, as described in the
following analysis. FDA believes that the proposed regulation will not
have a significant impact on a substantial number of small entities,
but conducted 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 the agency.
This proposed 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 proposed rule codifies the equipment performance
standards established under the Mammography Quality Standards Act of
1992 (MQSA) (Pub. L. 102-539) by proposing to require only x-ray
systems designed solely for mammography be marketed for mammography.
This proposal updates the x-ray performance standard to reflect a
standard already enforced under MQSA. Consequently, FDA expects no
economic impact from this portion of the proposed rule.
The proposed rule also proposes to permit 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 proposes to change the definition of an image receptor support
device, clarifying that it must provide a primary protective barrier
and that exposures should 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 while not allowing the
beam beyond the primary barrier protects the patient from unnecessary
exposure to radiation. FDA believes that most of the image receptor
support devices that are currently in use provide a primary protective
barrier that meets the requirements in the proposed 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 proposed
amendments to Secs. 1020.30(b) and 1020.31(m) will impose minimal new
costs. This proposal 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 proposed rule further proposes to exempt panoramic x-ray dental
units from the requirement that they be manufactured with exposure
timers which 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 proposal removes
a regulatory requirement, while still protecting the public health, and
may reduce costs to dental facilities and patients.
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 PHS Act (42 U.S.C. 201 et seq.) (PHS Act) to chapter V of the act.
These provisions regulate electronic products which emit radiation. On
October 27, 1992, the MQSA (Pub. L. 102-539) was enacted to establish
uniform, national quality standards for mammography. 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,
Sec. 900.12(b)(1) of the interim and final mammography regulations
prohibits the use of conventional radiographic equipment for
mammography. FDA has reviewed related Federal rules and has not
identified any other rules that duplicate, overlap, or conflict with
the proposed rule. FDA has also identified no new reporting,
recordkeeping or other compliance requirements associated with this
proposed rule.
There are approximately 10,000 mammography facilities in the United
States. Because this potential change in the performance standard only
applies to machines 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 1 year. At this
time, FDA is unable to estimate the demand for the proposed systems
modifications. As discussed previously, the proposed 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 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 established 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
[[Page 57962]]
manufacturers, none would be considered small entities. FDA invites
comments on this analysis of the number of entities that may be
affected by the proposed changes to the performance standard.
For the mandatory changes proposed for 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 proposed amendments to Secs. 1020.30(b)
and 1020.31(m). There are approximately 10,000 mammography facilities
in the United States. Because this potential 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 1 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 the 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 in 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 proposed changes to the performance standard, FDA
allows manufacturers and facilities to decide whether to implement any
device modifications in response to the greater flexibility proposed in
these mammography collimation requirements. If the benefits associated
with the flexibility proposed in this rulemaking are outweighed by the
costs to the facility, the facility can choose to not purchase a device
which has been modified in response to the greater flexibility proposed
in this rulemaking. With regard to the mandatory change proposed for
the primary barrier requirement, 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 proposed amendment to Sec. 1020.31(m). Therefore,
FDA does not anticipate that the proposed amendment to Sec. 1020.31(m)
will impose any significant costs.
Because most of these proposed changes to the mammography
performance standard and the proposed change to the timer requirement
for panoramic dental systems provide for greater flexibility, FDA
considered no alternatives to accomplish the stated objectives of the
applicable statutes. For the primary barrier standard proposed 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
FDA tentatively concludes that this proposed rule contains no new
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, 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. Section 1020.30 is amended by alphabetically adding a definition
to paragraph (b) to read as follows:
Sec. 1020.30 Diagnostic x-ray systems and their major components.
* * * * *
(b) * * *
Image receptor supporting 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 (the effective date of the final
rule) 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 which performs as
prescribed in paragraphs (f)(4)(i), (f)(4)(ii), and (f)(4)(iii) of this
section. For systems which 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 supporting 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.
* * * * *
(m) Primary protective barrier for mammography x-ray systems. For
mammography x-ray systems manufactured after (the effective date of the
final rule).
(1) At any SID where exposures can be made, the image receptor
support device shall provide a primary protective barrier which
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 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.
[[Page 57963]]
(4) Compliance 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: October 21, 1998.
William K. Hubbard,
Associate Commissioner for Policy Coordination.
[FR Doc. 98-28907 Filed 10-28-98; 8:45 am]
BILLING CODE 4160-01-F