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X-Ray Personnel Security Screening Systems Update Presented to TEPRSSC October 1, 2003 Gaithersburg, MD
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Background (1) Sep. 1998: TEPRSSC recommends a mandatory standard for backscatter systems. Apr. 1999: FDA proposes new consensus standard to ANSI/HPS N43. Apr. 2002: Radiation Safety for Personnel Screening Systems Using X Rays, becomes voluntary standard N43.17. June 2002: Transmission systems are discussed at TEPRSSC meeting – need for mandatory standard was restated.
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Background (2) In 2002 TEPRSSC recommended a mandatory standard based on ANSI N43.17 performance requirements. TEPRSSC also recognized that, although present transmission systems do not meet these requirements, there may be a limited number of legitimate uses for these systems (e.g. in lieu of a using a medical x-ray unit for the detection of swallowed contraband). It was proposed that the mandatory standard allow for exceptions, providing for appropriate manufacturer’s instructions, to allow such limited uses.
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ANSI N43.17 Dose Limits 0.1 Sv (10 µrem) effective dose per scan 250 Sv (25 mrem) effective dose per year
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New Documents Health Physics Society Position Statement: Use of ionizing radiation for security screening individuals. NCRP Presidential Report on Radiation Protection Advice: Screening of Humans for Security Purposes Using Ionizing Radiation Scanning Systems.
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HPS Position Statement (1) 1.The practice should be limited to those applications that result in an overall net benefit to society. 2.When the practice is used to screen members of the general public, screening systems and their use should conform to the requirements of ANSI/HPS N43.17. 3.Subjects should be informed of the radiation exposure.
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HPS Position Statement (2) Appropriate organizations should develop criteria for determining when the social benefits of public screening outweigh the risks associated with ionizing radiation exposure. The criteria should represent the consensus of professional, consumer- advocacy, labor, and business organizations; academic institutions; government agencies; and the general public.
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NCRP SC 1-12 FDA with co-sponsorship from the Transportation Security Administration (TSA) requested guidance from the National Council on Radiation Protection and Measurements (NCRP). “NCRP Presidential Report” format was chosen for speed (now being published as NCRP Commentary 16).
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FDA’s Request to NCRP for Guidance (1) Risk assessment Appropriate use conditions Targeted and susceptible populations Dose limits Informed consent
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Operator qualifications Benefit vs. risk (net benefit?) Record keeping General screening vs. follow-up evaluations FDA’s Request to NCRP for Guidance (2)
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NCRP Report SC 1-12: Scope (1) Is compatible with present NCRP system of radiation protection. Includes brief review of known risks. Considers potentially screened populations and susceptible subgroups. Makes dose recommendations based on radiation safety and usefulness of images.
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NCRP Report SC 1-12: Scope (2) Addresses: Need for communication of radiation exposure and effects Operator training requirements Recordkeeping Testing of equipment
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NCRP Report SC 1-12: Scope (3) Does not address: Net benefit - justification for use is outside of the role of NCRP
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NCRP Report SC 1-12: Bottom Line (1) Ionizing radiation dose from security screening must conform with NCRP-116 recommendation for frequent exposures for the general public: ≤ 1 mSv/y (100 mrem/y) effective dose from all non-medical, man- made sources
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NCRP Report SC 1-12: Bottom Line (2) The NCRP-116 administrative control of 0.25 mSv (25 mrem) annual effective dose to an individual from sources under one control (one venue) is a more practical alternative, albeit still potentially difficult to verify. The administrative control adequately protects all population groups.
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NCRP Report SC 1-12: Recommendations (1) Two Categories: 1.General-Use Systems Conform with ANSI N43.17 dose requirement of 0.1 Sv/scan (10 rem/scan) 2.Limited-Use Systems Between 0.1 and 10 Sv/scan (10 rem to 1 mrem/scan)
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NCRP Report SC 1-12: Recommendations (2) General-Use Systems May be used for screening general public. Limited-Use Systems Must be used with discretion (e.g. second tier screening). Should consider non-ionizing alternatives. Must limit usage so that any one individual not exceed 0.25 mSv in a year from one site.
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NCRP Report SC 1-12: Recommendations (3) Users of limited-use systems must assume responsibility of providing reasonable assurance that the annual administrative control is not exceeded. Written protocols Record keeping
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NCRP Report SC 1-12: Recommendations (4) Bystanders Should have the same level of protection as individuals screened (i.e. 0.25 mSv/y from one site). Operators The same level of protection is recommended.
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NCRP Report SC 1-12: Recommendations (5) Equipment testing Initially (after installation) After maintenance or repair Operator training See NCRP reports 127, 133, 134 List of 25 topics to be covered Annual refresher training followed by testing
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NCRP Report SC 1-12: Recommendations (6) Information to individual scanned Risk, benefit, and comparative examples Should be provided in lay terms prior to screening Should be disseminated and readily available Informed consent Not necessary
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Recapitulation In 2002 TEPRSSC recommended a mandatory standard based on ANSI N43.17 performance requirements. TEPRSSC also recognized that, although present transmission systems do not meet these requirements, there may be a limited number of legitimate uses for these systems (e.g. in lieu of a using a medical x-ray unit for the detection of swallowed contraband). It was proposed that the mandatory standard allow for exceptions, providing for appropriate manufacturer’s instructions, to allow such limited uses.
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Conclusion In the past year two leading radiation protection institutions, HPS and NCRP, went on record on the issue of x-ray screening of people for security purposes. Their recommendations are in harmony with the 2002 TEPRSSC recommendations. FDA will take all these documents and the previous CRCPD resolution into consideration in drafting a mandatory standard.
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