1、ISO/ASTM 51608:2015(E)Standard 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 indicates theyear of original
2、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 (bremsstrahlung) irradiator. Other proce
3、duresrelated 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 practices used in radiationproces
4、sing 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 Radiation Part 1: Requiremen
5、ts 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 routine con-trol of the proce
6、ss 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 radiation processing. It is intended
7、 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 onthe X-ray target (see Section
8、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 theresponsibility of the user of t
9、his 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 and Use of Mathematical Meth
10、-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 of Radiation-Sensitive Indic
11、ators51649 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 Processing51818 Practice for Dosimetr
12、y 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 Subcommittee E61.03 on DosimetryApplica
13、tion, 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 designation ISO15567:1998(E). The prese
14、nt 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 at serviceastm.org. ForAnnua
15、l Book of ASTM Standards volume information, refer to the standardsDocument Summary page on the ASTM website. ISO/ASTM International 2017 All rights reservedThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decisi
16、on on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.152701 Guide for Performance Characterization of Dosim-eters and Dosimetry Systems for use in Radiation Process-ing2.3 ISO Sta
17、ndards: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 processof irradiatio
18、n 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 Report 35 R
19、adiation 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 Guides in Metrol
20、ogy (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. The SIunit of
21、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 ofincremental mass d
22、m (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 that isstati
23、onary 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 Practice 51649
24、. 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 radiation processin
25、g, 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 motion. This
26、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 depends on the
27、 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 irradiation of a
28、 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 to theminimu
29、m 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 instrument(s)and p
30、rocedures.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 proceduresfor the system
31、s 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 energy of1.6
32、02 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.3Available from the
33、 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 of the Join
34、t 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 2017 All rights reserved 3.1.13 irradiation containerholder in which product isplaced during the irradiation process.3.1.13.1 Discussion“Ir
35、radiation 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 continual contr
36、ol 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 documenting
37、 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 configuration irradiate
38、d 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 absorption and scat
39、tering 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 the produc
40、t,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, simulated pro
41、duct 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 bremsstrahlung and the
42、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 used as an adj
43、ective 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 electron bea
44、m 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 dosimetry may
45、 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 value or to
46、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 the purpose
47、 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 onto polyme
48、rs;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 regulated irradia
49、tion 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, routine dosimetry maybe used to monitor the reproducibility of the radiation process.4.2 Radiation processing specifications usually include apair of absorbed-dose l
