1、ANSI N42.46-2008American National Standard for Determination of the Imaging Performance of X-Ray and Gamma-Ray Systems for Cargo and Vehicle Security ScreeningIEEE3 Park Avenue New York, NY 10016-5997, USA19 August 2008Accredited by the American National Standards InstituteSponsored by theNational C
2、ommittee on Radiation Instrumentation, N42N42.46ANSI N42.46-2008 American National Standard for Determination of the Imaging Performance of X-Ray and Gamma-Ray Systems for Cargo and Vehicle Security Screening Sponsor National Committee on Radiation Instrumentation, N42 Accredited by the American Nat
3、ional Standards Institute Secretariat Institute of Electrical and Electronics Engineers, Inc. Approved 19 May 2008 American National Standards Institute Abstract: This standard is intended to be used to determine the imaging performance of x-ray and gamma-ray systems utilized to inspect loaded or em
4、pty vehicles, including personal and commercial vehicles of any type; marine and air cargo containers of any size; railroad cars; and palletized or unpalletized cargo larger than 1 m 1 m in cross-section. Keywords: cargo/vehicle security screening, contrast sensitivity, gamma ray, imaging performanc
5、e, penetration, spatial resolution, wire detection, x-ray The Institute of Electrical and Electronics Engineers, Inc. 3 Park Avenue, New York, NY 10016-5997, USA Copyright 2008 by the Institute of Electrical and Electronics Engineers, Inc. All rights reserved. Published 19 August 2008. Printed in th
6、e United States of America. IEEE is a registered trademark in the U.S. Patent +1-978-750-8400. Permission to photocopy portions of any individual standard for educational classroom use can also be obtained through the Copyright Clearance Center. Introduction This introduction is not part of ANSI N42
7、.46-2008, American National Standard for Determination of the Imaging Performance of X-Ray and Gamma-Ray Systems for Cargo and Vehicle Security Screening. This standard is the responsibility of the Accredited American Standards Committee on Radiation Instrumentation, N42. The standard was approved b
8、y the N42 letter ballot of November 2007January 2008. Notice to users Laws and regulations Users of these documents should consult all applicable laws and regulations. Compliance with the provisions of this standard does not imply compliance to any applicable regulatory requirements. Implementers of
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15、his URL for errata periodically. v Copyright 2008 IEEE. All rights reserved. Interpretations Current interpretations can be accessed at the following URL: http:/standards.ieee.org/reading/ieee/interp/ index.html. Patents Attention is called to the possibility that implementation of this standard may
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18、d are expressly advised that determination of the validity of any patent rights, and the risk of infringement of such rights, is entirely their own responsibility. Further information may be obtained from the IEEE Standards Association. vi Copyright 2008 IEEE. All rights reserved. Participants At th
19、e time it approved this standard, the Accredited Standards Committee on Radiation Instrumentation, N42, had the following membership: Michael P. Unterweger, Chair Louis Costrell, Deputy Chair William Ash, Administrative Secretary Organization Represented.Name of Representative Bartlett Services .Mor
20、gan Cox Canberra Markku Koskelo Chew, M.H .Jack M. Selby Commerce Dept, U.S. NIST Michael P. Unterweger Louis Costrell (Alt.) Consultant Frank X. Masse Department of Homeland Security .Peter Shebell Entergy-ANO .Ron Schwartz Health Physics Society .Sandy Perle IEEE Louis Costrell .Anthony Spurgin (A
21、lt.) .Michael P. Unterweger (Alt.) International Medcom Don Sythe Lawrence Berkeley National Lab .Edward J. Lampo Lawrence Livermore National Lab .Gary Johnson NASA, GSFC . R. Sachidananda Babu Nuclear Regulatory Commission Cynthia Jones Nuclear Standards Unlimited .Al N. Tschaeche Oak Ridge Nationa
22、l Laboratory .Peter J. Chiaro, Jr. .Charles Britton (Alt.) ORTEC Ronald M. Keyser Pacific Northwest National Laboratory .Richard Kouzes Swinth Associates .Kenneth L. Swinth U.S. Army Edward Groeber U.S. Nuclear Regulatory CommissionCynthia G. Jones Members-At-Large .Ernesto Corte .Joseph C. McDonald
23、 .Paul L. Phelps .Joseph Stencel .Lee J. Wagner vii Copyright 2008 IEEE. All rights reserved. viii Copyright 2008 IEEE. All rights reserved. At the time this standard was completed, Subcommittee N42.HSI had the following membership: Morgan Cox, Chair Michael P. Unterweger, Vice Chair Paul Bailey Pet
24、er J. Chairo, Jr David Gilliam Mark Hoover Cynthia G. Jones Ronald Keyser Richard Kouzes Joseph C. McDonald Leticia Pibida Brian Rees Peter Shebell David Trombino At the time this standard was completed, the ANSI N42.46 Working Group had the following membership: Raymond D. Mintz, Chair Jim Lamers,
25、Vice Chair Curtis Bell Paul M. Bergstrom Greg Budner Tom Cassidy Frank Cerra Michael W. Curtin Andy Dancisin Robert Frankle Gordon Gillerman Nick Gillett Larry Hudson Siraj Khan Kevin Keaty John LaRegina Roland Liu Roy Lindquist Luke McCormick Brian Mee Rex Richardson Fred Roder Wade Sapp Steve Selt
26、zer Mark Torbek David Waters Stacy G. Wright Contents 1. Overview 1 1.1 Scope . 2 1.2 Purpose 2 2. Definitions 2 3. General considerations . 4 3.1 Special word usage 4 4. Performance measurement procedures . 4 4.1 General requirements . 4 4.2 Standard test conditions . 4 4.3 Radiation field measurem
27、ents 5 4.4 Documentation . 6 4.5 Image quality measurement objectives and scope . 7 4.6 Test object positions 7 4.7 Penetration . 8 4.8 Spatial resolution . 10 4.9 Wire detection 12 4.10 Contrast sensitivity 13 Annex A (informative) Bibliography . 16 Annex B (informative) Documentation for Image-Qua
28、lity measurements . 17 Annex C (informative) Representative test fixtures . 26 ix Copyright 2008 IEEE. All rights reserved. American National Standard for Determination of the Imaging Performance of X-Ray and Gamma-Ray Systems for Cargo and Vehicle Security Screening IMPORTANT NOTICE: This standard
29、is not intended to assure safety, security, health, or environmental protection in all circumstances. Implementers of the standard are responsible for determining appropriate safety, security, environmental, and health practices or regulatory requirements. This IEEE document is made available for us
30、e subject to important notices and legal disclaimers. These notices and disclaimers appear in all publications containing this document and may be found under the heading “Important Notice” or “Important Notices and Disclaimers Concerning IEEE Documents.” They can also be obtained on request from IE
31、EE or viewed at http:/standards.ieee.org/IPR/disclaimers.html. 1. Overview This standard is organized according to the following list: Clause 1 provides the scope and purpose of this standard. Clause 2 provides definitions for those users not familiar with x-ray and gamma-ray systems and/or their ap
32、plication to cargo and vehicle security screening. Clause 3 sets forth the general considerations necessary for application of this standard, including special word usage, environmental factors, safety requirements and installation code compatibility. Clause 4 describes the requisite test conditions
33、, documentation, test objects, test-object locations and test procedures to measure imaging performance in terms of penetration, spatial resolution, wire detection, and contrast sensitivity. Annex A provides an informative list of references. Annex B provides example data sheets to record the result
34、s of the imaging tests conducted according to this standard. Annex C illustrates test fixtures. 1 Copyright 2008 IEEE. All rights reserved. ANSI N42.46-2008 American National Standard for Determination of the Imaging Performance of X-Ray and Gamma-Ray Systems for Cargo and Vehicle Security Screening
35、 1.1 Scope This standard is intended to be used to determine the imaging performance of x-ray and gamma-ray systems utilized to inspect loaded or empty vehicles, including personal and commercial vehicles of any type; marine and air cargo containers of any size; railroad cars; and palletized or unpa
36、lletized cargo larger than 1 m 1 m in cross-section. The standard applies to systems that are the following: Single or multiple energy, source, or view Employ primary (i.e., transmission) and/or scatter (e.g., backscatter) radiation detection Used to detect prohibited and controlled materials and/or
37、 to verify manifests Primarily imaging systems but also may have complementary features such as material discrimination and automatic active or passive threat alerts. This standard does not address how to test these complementary features. Adherence to all applicable mechanical and electrical safety
38、 requirements and compatibility with all applicable installation codes, including electro-magnetic compatibility requirements, is extremely important for any type of x-ray or gamma-ray screening system; however, identification of these requirements is not within the scope of this standard. 1.2 Purpo
39、se The purpose of this document is to provide standard, repeatable and verifiable methods to describe and measure the imaging performance characteristics of the systems listed above. It is not intended to determine the capability of a security screening system under specific operational inspection c
40、onditions. 2. Definitions The following definitions apply to ANSI/IEEE standards that have been developed at the request of the Department of Homeland Security (DHS) for instruments to be used by DHS and emergency responders. 2.1 air cargo container: A closed container, usually of aluminum or fabric
41、 with a steel floor, used to hold cargo transported by air. 2.2 backscatter: The deflection of radiation through angles greater than 90 to the initial direction of travel, or the radiation so deflected. 2.3 beam energy: The maximum emitted energy of an x-ray or gamma-radiation source, usually measur
42、ed in multiples of a thousand electron volts (keV) or a million electron volts (MeV). 2.4 blocking material: Energy-absorbent material, usually steel of varying thickness, placed between a radiation source and the test object to be imaged. 2.5 cabinet x-ray system: A radiographic system meeting the
43、requirement of FCC Code of Federal Regulations Title 21, Part 1020.40 with respect to radiation levels outside the system and access to the interior of the system; usually applied to systems for inspecting parcels, baggage and small cargo. 2.6 cargo density: Mean cargo density measured in grams per
44、cubic centimeter (g/cm3). 2 Copyright 2008 IEEE. All rights reserved. ANSI N42.46-2008 American National Standard for Determination of the Imaging Performance of X-Ray and Gamma-Ray Systems for Cargo and Vehicle Security Screening 2.7 contrast sensitivity: The percent of change in the thickness of a
45、n otherwise uniform material that is minimally perceptible in the x-ray or gamma-ray image. 2.8 detector: A device that converts ionizing radiation to a corresponding electrical signal. 2.9 dual-energy system: An x-ray system operating at two discrete voltages that can be capable of distinguishing d
46、ifferences in the photon-atom interaction cross-sections. 2.10 dual-view system: A system providing two images of an object obtained at two different aspect angles. 2.11 gray (Gy): The SI unit of absorbed dose of radiation; one Gy is equal to an absorbed dose of 1 J/kg (100 rads). 2.12 isodose conto
47、ur: A perimeter around the screening system on which all points receive equal amounts of radiation dose from an operational energy source; it is used in this standard to aid in obtaining measurements of imaging performance under consistent and comparable conditions. 2.13 known occupant: A person visible in a vehicle; e.g., driver or passenger. 2.14
