[Federal Register Volume 63, Number 209 (Thursday, October 29, 1998)]
[Proposed Rules]
[Pages 57957-57963]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-28907]


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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