1 Thomas B. Shope Office of Science and Technology Center for Devices and Radiological Health U.S....

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Thomas B. ShopeOffice of Science and Technology

Center for Devices and Radiological HealthU.S. Food and Drug Administration

Rockville, Maryland

tbs@cdrh.fda.gov301-443-3314 ext. 132

Update on Proposed Amendments

to the Performance Standard for Diagnostic X-ray Systems

(21 CFR 1020.30 - .33)(The Fluoroscopic System Amendments)

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Outline

Background on amendment development.

Status of comments.

Estimated schedule for completion.

Future role of international standards?

Advice or comment from the committee

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Background

Community recognized need for amendments to address changes in technology in early 1990s• Increased radiation output capability and new imaging

modes• Digital subtraction angiography, lithotripsy systems• 1992 ACR/FDA Workshop on Fluoroscopy

► Consensus on need for display of patient dose info Development of IEC Standard 60601-2-43: Particular

requirements for the safety of X-ray equipment for interventional procedures

Concerns over radiation injuries from fluoroscopy

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FDA’s Actions Regarding Fluoroscopic X-ray

Systems 1993 - Proposed rule regarding limit on maximum

exposure rate during high-level control mode 1995 - Final rule effective, other amendments needed 1997 - ANPR for additional amendments published Discussion of concepts for amendments and proposed

rule with TEPRSSC at 1997 and 1998 meetings “Year 2000 Problem” diverts resources/delays

progress

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FDA’s Actions Regarding Fluoroscopic X-ray

Systems December 2002 - Proposed rule published following

development of impact analysis, estimates of costs and benefits

Comment period ended April 10, 2003

FDA consideration of comments

Preparation of Final Rule

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Comments on proposed rule

Comments from 12 individuals or organizations• Two state agencies• Three professional associations• One industry association• Two x-ray equipment manufacturers• Four individuals, including one medical physicist

and one radiation effects researcher Comments, in general, were in favor of

amendments

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Comments on proposed rule

Some objections to specific proposals or details Changes suggested to the standard that were not

part of FDA’s proposal - Such changes would generally require an additional proposal for comment• Definitions, clarifications, significant changes

Several comments urged “harmoniztion” with IEC standards for x-ray equipment

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Examples of specific comments

Modify definitions Desire to consult/confer with FDA on development

of additional requirements• Dose limits for input to the image receptor• Imaging performance• Characterization and requirements for solid state

x-ray imaging devices

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Comments on Definitions

Attenuation block - size, thickness Mode of operation - single control in IEC standard C-arm fluoroscope Exposure - definition of second meaning (loading) Isocenter Solid state x-ray imaging device Visible area Others

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Critiques of proposed requirements

Manufacturer description of intended uses for specific modes of operation in user information

Manner and accuracy of dose display data Ultimate responsibility for modifications initiated by

user/owner Audible signal during fluoroscopy - conflict with

current IEC standard 60601-2-7 for generators Application of dose display and last image hold to

mini C-arm systems (SID < 45 cm)

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Reference location for system with isocenter

Shield

Shield

Monitor

15 cm

Dose rate orcumulative doseat reference point

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8.3mGy/minmGy

During irradiationAir kerma rate

mGy/minmGy66.8

Following irradiationCumulative air kerma

Proposed display of dose information

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mGy/min

mGy

Air kerma rate

Cumulative air kerma

Display of air kerma rate during irradiation.

Continuous display of cumulative air kerma.

Alternative display of dose information

4.8

127.5

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Accuracy of dose display?

Proposed accuracy of display of 25%

IEC Standard 60601-2-43 requires 50%

Is an accuracy of better than 50% necessary?

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Critiques of proposed requirements

Manufacturer description of intended uses for specific modes of operation in user information

Manner and accuracy of dose display data Ultimate responsibility for modifications initiated by

user/owner Audible signal during fluoroscopy - conflict with

current IEC standard 60601-2-7 for generators Application of dose display and last image hold to

mini C-arm systems (SID < 45 cm)

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Additional changes not in NPR

Require info and tools for troubleshooting, repair, service, and testing

Specification of voltage (kVp) waveform Use specific IEC requirements - dose info, test

procedures, primary protective barrier Display peak skin dose and “skin dose map” Display of collimation without irradiation Indication of x-ray beam-on and “live image” Post-exposure “image cropping” of digital images

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Skin dose “mapping” system

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Additional changes not in NPR

Require info and tools for troubleshooting, repair, service, and testing

Specification of voltage (kVp) waveform Use specific IEC requirements - dose info, test

procedures, primary protective barrier Display peak skin dose and “skin dose map” Display of collimation without irradiation Indication of x-ray beam-on and “live image” Post-exposure “image cropping” of digital images

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Electronic “cropping” of digital images

Area of imagereceptor

X-ray field area

Area of stored image

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Electronic “cropping” of digital images

Stored and displayed image

X-ray field

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“Cropping” of poorly collimated image

Area of imagereceptor

X-ray field

Area of stored image

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X-ray field border

Stored and displayed image

“Cropping” of poorly collimated image

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Question?

Are requirements about “electronic cropping” of digital images needed in performance standards for digital diagnostic x-ray systems?

Initial display versus storage of images?

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Errors and omissions noted

Discussion of “unique” modes of operation and dose information for them

Omission of effective date for 1020.32(m)(2) and clarification of requirement to indicate filtration used

Attenuation of material between patient and image receptor

Tolerance on dose display data - 1020.30(h)(6)(i) Typo in proposed 1020.32(k)(5)(ii) describing the

alternate location of the reference point

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Schedule for completion

Finalize decisions regarding regulatory wording

Draft Federal Register notice for final rule that responds to comments

CDRH, FDA, HHS and OMB review of FR notice

Anticipate completion by end of calendar 2003, rule would be effective in late 2004 or early 2005.

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Future role of international (IEC)

standards? Relationship between U.S. and IEC standards needs attention in global economy?• No IEC standards when U.S. std. Developed• Process for developing IEC standards different from

the regulatory process►Consensus of national committees►Maintenance teams - structure being revised

• Are IEC standards “enforced” on manufacturers?• FDA standards address only radiation safety

performance

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Future role of international (IEC)

standards? Could IEC standards be used in place of U.S.

standards (for medical x-ray, for other electronic products)?• How could they be enforced?• Impact on State radiation control programs?• Impact on Federal preemption?• Could medical device authorities be used to

assure compliance with “voluntary” IEC stds?

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Future role of international (IEC)

standards?• Could IEC standards be used without legislative

changes?• Would public health be protected if reliance

placed on IEC standards?• Could FDA or U.S. national committee play

effective role in maintenance of IEC standards? • Do current problems with Dx x-ray systems

warrant continued mandatory standard?• Would greater public health impact be obtained

through other FDA activities?

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Comments & Questions