1、ISO/ASTM 51608:2015(E)An American National StandardStandard Practice forDosimetry in an X-Ray (Bremsstrahlung) Facility forRadiation Processing at Energies between 50 keV and 7.5MeV1This standard is issued under the fixed designation ISO/ASTM 51608; the number immediately following the designation i
2、ndicates theyear of original adoption or, in the case of revision, the year of last revision.1. Scope1.1 This practice outlines the dosimetric procedures to befollowed during installation qualification, operationalqualification, performance qualification and routine processingat an X-ray (bremsstrah
3、lung) irradiator. Other proceduresrelated to operational qualification, performance qualificationand routine processing that may influence absorbed dose in theproduct are also discussed.NOTE 1Dosimetry is only one component of a total quality assuranceprogram for adherence to good manufacturing prac
4、tices used in radiationprocessing applications.NOTE 2ISO/ASTM Practices 51649, 51818 and 51702 describedosimetric procedures for electron beam and gamma facilities for radia-tion processing.1.2 For radiation sterilization of health care products, seeISO 11137-1, Sterilization of health care products
5、 Radiation Part 1: Requirements for development, validation androutine control of a sterilization process for medical devices.Inthose areas covered by ISO 11137-1, that standard takesprecedence.1.3 For irradiation of food, see ISO 14470, Food irradiation Requirements for development, validation and
6、routine con-trol of the process of irradiation using ionizing radiation forthe treatment of food. In those areas covered by ISO 14470,that standard takes precedence.1.4 This document is one of a set of standards that providesrecommendations for properly implementing and utilizingdosimetry in radiati
7、on processing. It is intended to be read inconjunction with ISO/ASTM Practice 52628, “Practice forDosimetry in Radiation Processing”.1.5 In contrast to monoenergetic gamma radiation, theX-ray energy spectrum extends from low values (about 35keV) up to the maximum energy of the electrons incident ont
8、he X-ray target (see Section 5 and Annex A1).1.6 Information about effective or regulatory dose limits andenergy limits for X-ray applications is not within the scope ofthis practice.1.7 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is there
9、sponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced documents2.1 ASTM Standards:2E170 Terminology Relating to Radiation Measurements andDosimetryE2232 Guide for Selection
10、 and Use of Mathematical Meth-ods for Calculating Absorbed Dose in Radiation Process-ing ApplicationsE2303 Guide for Absorbed-Dose Mapping in RadiationProcessing Facilities2.2 ISO/ASTM Standards:251261 Practice for Calibration of Routine Dosimetry Sys-tems for Radiation Processing51539 Guide for Use
11、 of Radiation-Sensitive Indicators51649 Practice for Dosimetry in an Electron Beam Facilityfor Radiation Processing at Energies Between 300 keVand 25 MeV51702 Practice for Dosimetry in a Gamma Facility forRadiation Processing51707 Guide for Estimating Uncertainties in Dosimetry forRadiation Processi
12、ng51818 Practice for Dosimetry in an Electron Beam Facilityfor Radiation Processing at Energies Between 80and 300keV52628 Practice for Dosimetry in Radiation Processing1This practice is under the jurisdiction of ASTM Committee E61 on RadiationProcessing and is the direct responsibility of Subcommitt
13、ee E61.03 on DosimetryApplication, and is also under the jurisdiction of ISO/TC 85/WG 3.Current edition approved Sept. 8, 2014. Published February 2015. Originallypublished as ASTM E 160894. Last previous ASTM edition E 160800. ASTM E160894 was adopted by ISO in 1998 with the intermediate designatio
14、n ISO15567:1998(E). The present International Standard ISO/ASTM 51608:2015(E) is amajor revision of the last previous edition ISO/ASTM 51608:2005(E), whichreplaced ISO/ASTM 51608:2002(E).2For referenced ASTM or ISO/ASTM standards, visit the ASTM website,www.astm.org, or contact ASTM Customer Service
15、 at serviceastm.org. ForAnnual Book of ASTM Standards volume information, refer to the standardsDocument Summary page on the ASTM website. ISO/ASTM International 2015 All rights reserved152701 Guide for Performance Characterization of Dosim-eters and Dosimetry Systems for use in Radiation Process-in
16、g2.3 ISO Standards:3ISO 11137-1 Sterilization of health care products Radia-tion Part 1: Requirements for development, validationand routine control of a sterilization process for medicaldevicesISO 14470 Food irradiation Requirements for thedevelopment, validation and routine control of the processo
17、f irradiation using ionizing radiation for the treatment offood2.4 International Commission on Radiation Units and Mea-surements (ICRU) Reports:4ICRU Report 14 Radiation Dosimetry: X Rays and GammaRays with Maximum Photon Energies Between 0.6 and 50MeVICRU Report 34 Dosimetry of Pulsed RadiationICRU
18、 Report 35 Radiation Dosimetry: Electron Beams withEnergies Between 1 and 50 MeVICRU Report 37 Stopping Powers for Electrons and Posi-tronsICRU Report 80 Dosimetry Systems for Use in RadiationProcessingICRU Report 85a Fundamental Quantities and Units forIonizing Radiation2.5 Joint Committee for Guid
19、es in Metrology (JCGM)Report:JCGM 100:2008, GUM 1995, with minor corrections,Evaluation of measurement dataGuide to the expressionof uncertainty in measurement53. Terminology3.1 Definitions:3.1.1 absorbed dose (D)quantity of ionizing radiationenergy imparted per unit mass of a specified material. Th
20、e SIunit of absorbed dose is the gray (Gy), where 1 gray isequivalent to the absorption of 1 joule per kilogram of thespecified material (1 Gy = 1 J/kg). The mathematical relation-ship is the quotient of d by dm, where d is the meanincremental energy imparted by ionizing radiation to matter ofincrem
21、ental mass dm (see ICRU Report 85a).D 5 d/dm (1)3.1.2 beam lengthdimension of the irradiation zone alongthe direction of product movement, at a specified distance fromthe accelerator window.3.1.2.1 DiscussionBeam length is perpendicular to beamwidth and to the electron beam axis. In case of product
22、that isstationary during irradiation, beam length and beam widthmay be interchangeable.3.1.3 beam widthdimension of the irradiation zone per-pendicular to the direction of product movement, at a specifieddistance from the accelerator window.3.1.3.1 DiscussionFor graphic illustration, see ISO/ASTM Pr
23、actice 51649. This term usually applies to electronirradiation.3.1.4 bremsstrahlungbroad-spectrum electromagnetic ra-diation emitted when an energetic charged particle is influ-enced by a strong electric or magnetic field, such as that in thevicinity of an atomic nucleus.3.1.4.1 DiscussionIn radiati
24、on processing, bremsstrahl-ung photons with sufficient energy to cause ionization aregenerated by the deceleration or deflection of energetic elec-trons in a target material. When an electron passes close to anatomic nucleus, the strong coulomb field causes the electron todeviate from its original m
25、otion. This interaction results in aloss of kinetic energy by the emission of electromagneticradiation. Such encounters are uncontrolled and they produce acontinuous photon energy distribution that extends up to themaximum kinetic energy of the incident electron. Thebremsstrahlung energy spectrum de
26、pends on the electronenergy, the composition and thickness of the X-ray target, andthe emission direction of photon angle of emission with respectto the incident electron.3.1.5 charged-particle equilibrium (referred to as electronequilibrium in the case of electrons set in motion by photon-beam irra
27、diation of a material)condition in which the kineticenergy of charged particles (or electrons), excluding rest mass,entering an infinitesimal volume of the irradiated materialequals the kinetic energy of charge particles (or electrons)emerging from it.3.1.6 dose uniformity ratioratio of the maximum
28、to theminimum absorbed dose within the irradiated product.3.1.6.1 DiscussionThe concept is also referred to as themax/min dose ratio.3.1.7 dosimeterdevice that, when irradiated, exhibits aquantifiable change that can be related to absorbed dose in agiven material using appropriate measurement instru
29、ment(s)and procedures.3.1.8 dosimeter responsereproducible, quantifiable effectproduced in the dosimeter by ionizing radiation.3.1.9 dosimetry systemsystem used for measuring ab-sorbed dose, consisting of dosimeters, measurement instru-ments and their associated reference standards, and proceduresfo
30、r the systems use.3.1.10 electron energykinetic energy of an electron.3.1.10.1 DiscussionUnit is usually electron volt (eV),kiloelectron volt (keV), or megaelectron volt (MeV). 1 eV isthe kinetic energy acquired by a single electron acceleratedthrough a potential difference of 1 V. 1 eV is equal to
31、energy of1.602 10-19joules.3.1.11 electron energy spectrumparticle fluence distribu-tion of electrons as a function of energy.3.1.12 installation qualification (IQ)process of obtainingand documenting evidence that equipment has been providedand installed in accordance with its specifications.3Availa
32、ble from the International Organization for Standardization, 1 Rue deVaremb, Case Postale 56, CH1211, Geneva 20, Switzerland.4Available from the International Commission on Radiation Units andMeasurements, 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814, U.S.A.5Document produced by Working Group 1
33、 of the Joint Committee for Guides inMetrology (JCGM/WG 1). Available free of charge at the BIPM website (http:/www.bipm.org).ISO/ASTM 51608:2015(E)2 ISO/ASTM International 2015 All rights reserved3.1.13 irradiation containerholder in which product isplaced during the irradiation process.3.1.13.1 Di
34、scussion“Irradiation container” is often re-ferred to simply as “container” and can be a carrier, cart, tray,product carton, pallet, product package or other holder.3.1.14 measurement management systemset of interre-lated or interacting elements necessary to achieve metrologicalconfirmation and cont
35、inual control of measurement processes.3.1.15 operational qualification (OQ)process of obtainingand documenting evidence that installed equipment operateswithin predetermined limits when used in accordance with itsoperational procedures.3.1.16 performance qualification (PQ)process of obtain-ing and
36、documenting evidence that the equipment, as installedand operated in accordance with operational procedures, con-sistently performs in accordance with predetermined criteriaand thereby yields product meeting its specification.3.1.17 process loadvolume of material with a specifiedloading configuratio
37、n irradiated as a single entity.3.1.18 processing categorygroup of different product thatcan be processed together.3.1.18.1 DiscussionProcessing categories can be basedon, for instance, composition, density or dose requirements.3.1.19 reference materialhomogeneous material of knownradiation absorpti
38、on and scattering properties used to establishcharacteristics of the irradiation process, such as scanuniformity, depth-dose distribution, throughput rate, and repro-ducibility of dose delivery.3.1.20 simulated productmaterial with radiation attenua-tion and scattering properties similar to those of
39、 the product,material or substance to be irradiated.3.1.20.1 DiscussionSimulated product is used during irra-diator characterization as a substitute for the actual product,material or substance to be irradiated. When used in routineproduction runs in order to compensate for the absence ofproduct, si
40、mulated product is sometimes referred to as com-pensating dummy. When used for absorbed-dose mapping,simulated product is sometimes referred to as phantom mate-rial.3.2 Definitions of Terms Specific to This Standard:3.2.1 X-radiationionizing electromagnetic radiation,which includes both bremsstrahlu
41、ng and the characteristicradiation emitted when atomic electrons make transitions tomore tightly bound states. See bremsstrahlung.3.2.1.1 DiscussionIn radiation processing applications,the principal X-radiation is bremsstrahlung.3.2.2 X-rayof or relating to X-radiation.3.2.2.1 DiscussionX-ray is use
42、d as an adjective whileX-radiation is used as a noun.3.2.3 X-ray converterdevice for generating X-radiation(bremsstrahlung) from an electron beam, consisting of a target,means for cooling the target, and a supporting structure.3.2.4 X-ray targetcomponent of the X-ray converter thatis struck by the e
43、lectron beam and which produces X-radiation.3.2.4.1 DiscussionThe X-ray target is usually made ofmetal with a high atomic number (such as tantalum), highmelting temperature, and high thermal conductivity.3.3 Definitions of other terms used in this standard thatpertain to radiation measurement and do
44、simetry may be foundin ASTM Terminology E170. Definitions in E170 are compat-ible with ICRU Report 85a, which may be used as analternative reference.4. Significance and use4.1 A variety of products and materials are irradiated withX-radiation to modify their characteristics and improve theeconomic v
45、alue or to reduce their microbial population forhealth-related purposes. Dosimetry requirements might varydepending on the type and end use of the product. Someexamples of irradiation applications where dosimetry may beused are:4.1.1 Sterilization of health care products;4.1.2 Treatment of food for
46、the purpose of parasite andpathogen control, insect disinfestation, and shelf life extension;4.1.3 Disinfection of consumer products;4.1.4 Cross-linking or degradation of polymers and elasto-mers;4.1.5 Curing composite material;4.1.6 Polymerization of monomers and oligomer and graft-ing of monomers
47、onto polymers;4.1.7 Enhancement of color in gemstones and other mate-rials;4.1.8 Modification of characteristics of semiconductor de-vices; and4.1.9 Research on materials effects of irradiation.NOTE 3Dosimetry with measurement traceability and with knownmeasurement uncertainty is required for regula
48、ted irradiation processes,such as the sterilization of health care products and treatment of food.Dosimetry may be less important for other industrial processes, such aspolymer modification, which can be evaluated by changes in the physicalproperties of the irradiated materials. Nevertheless, routin
49、e dosimetry maybe used to monitor the reproducibility of the radiation process.4.2 Radiation processing specifications usually include apair of absorbed-dose limits: a minimum value to ensure theintended beneficial effect and a maximum value that theproduct can tolerate while still meeting its functional orregulatory specifications. For a given application, one or bothof these values may be prescribed by process specifications orregulations. Knowledge of the dose distribution within irradi-ated material is essential to he
