1、Designation: E2303 111An American National StandardStandard Guide forAbsorbed-Dose Mapping in Radiation Processing Facilities1This standard is issued under the fixed designation E2303; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision
2、, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEEditorial changes were made throughout in December 2012.1. Scope1.1 This document provides guidance in determin
3、ingabsorbed-dose distributions (mapping) in products, materialsor substances irradiated in gamma, X-ray (bremsstrahlung) andelectron beam facilities.NOTE 1For irradiation of food and the radiation sterilization of healthcare products, specific ISO and ISO/ASTM standards containing dosemapping requir
4、ements exist. See ISO/ASTM Practices 51431, 51608,51649, 51702 and 51818 and ISO 11137-1. Regarding the radiationsterilization of health care products, in those areas covered by ISO11137-1, that standard takes precedence.1.2 This guide is one of a set of standards that providesrecommendations for pr
5、operly implementing dosimetry inradiation processing. it is intended to be read in conjunctionwith ASTM Practice E2628.1.3 Methods of analyzing the dose map data are described.Examples are provided of statistical methods that may be usedto analyze dose map data.1.4 Dose mapping for bulk flow process
6、ing and fluidstreams is not discussed.1.5 Dosimetry is an element of a total quality managementsystem for an irradiation facility. Other controls besides do-simetry may be required for specific applications such asmedical device sterilization and food preservation.1.6 This standard does not purport
7、to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory requirements prior to use.2. Referenced Documents2.1 ASTM Standards:2E170 T
8、erminology Relating to Radiation Measurements andDosimetryE178 Practice for Dealing With Outlying ObservationsE2232 Guide for Selection and Use of Mathematical Meth-ods for Calculating Absorbed Dose in Radiation Process-ing ApplicationsE2628 Practice for Dosimetry in Radiation Processing2.2 ISO/ASTM
9、 Standards:251261 Guide for Selection and Calibration of DosimetrySystems for Radiation Processing51431 Practice for Dosimetry in Electron Beam and X-Ray(Bremsstrahlung) Irradiation Facilities for Food Process-ing51608 Practice for Dosimetry in an X-ray (Bremsstrahlung)Facility for Radiation Process
10、ing51649 Practice for Dosimetry in an Electron Beam Facilityfor Radiation Processing at Energies between 300 keVand25 MeV51702 Practice for Dosimetry in a Gamma Irradiation Facil-ity for Radiation Processing51707 Guide for Estimating Uncertainties in Dosimetry forRadiation Processing51818 Practice f
11、or Dosimetry in an Electron Beam Facilityfor Radiation Processing at Energies between 80 and 300keV2.3 International Commission on Radiation Units and Mea-surements Reports:3ICRU Report 60 Fundamental Quantities and Units forIonizing Radiation2.4 International Organization for Standardization:4ISO 1
12、1137-1 Sterilization of health care products Radia-tion Part 1: Requirements for development, validation,and routine control of a sterilization process for medicaldevicesGUM Guide to the Expression of Uncertainty inMeasurement, 1995, ISBN 92-6710188-91This guide is under the jurisdiction of ASTM Com
13、mittee E61 on RadiationProcessingand is the direct responsibility of Subcommittee E61.03 on DosimetryApplication.Current edition approved July 1, 2011. Published August 2011. Originallyapproved in 2003. Last previous edition approved in 2003 as E2303-03. DOI:10.1520/E2303-11E01.2For referenced ASTM
14、and ISO/ASTM standards, visit the ASTM website,www.astm.org, or contact ASTM Customer Service at serviceastm.org. ForAnnual Book of ASTM Standards volume information, refer to the standardsDocument Summary page on the ASTM website.3Available from International Commission on Radiation Units andMeasur
15、ements, 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814.4Available from International Organization for Standardization (ISO), 1 rue deVaremb, Case postale 56, CH-1211, Geneva 20, Switzerland.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United
16、States1VIM International Vocabulary of Basic and General Termsin Metrology3. Terminology3.1 Definitions:3.1.1 absorbed-dose mappingmeasurement of absorbeddose within an irradiated product to produce a one-, two- orthree-dimensional distribution map of absorbed dose.3.1.1.1 DiscussionFor a process lo
17、ad, such a dose map isobtained using dosimeters placed at specified locations withinthe process load.3.1.2 calibration curve (VIM:2008)expression of the re-lation between indication and corresponding measured quantityvalue.3.1.2.1 DiscussionIn radiation processing standards, theterm “dosimeter respo
18、nse” is generally used for “indication.”3.1.3 dose map, dose mappingsee absorbed-dose map-ping.3.1.4 dose uniformity ratioratio of the maximum to theminimum absorbed dose within the irradiated product.3.1.4.1 DiscussionThe concept is also referred to as themax/min dose ratio. Product generally refer
19、s to the “processload.”3.1.5 dose zonea region or discrete point(s) within aprocess load that receives the same absorbed dose within thestatistical uncertainty of the irradiation process and absorbed-dose measurement(s).3.1.6 installation qualification (IQ)process of obtainingand documenting evidenc
20、e that equipment has been providedand installed in accordance with its specification.3.1.7 irradiation containerholder in which process load istransported through the irradiator.3.1.7.1 Discussion“Irradiation container” is often referredto simply as “container” and can be a carrier, cart, try, produ
21、ctcarton, pallet, product package or other holder.3.1.8 operational qualification (OQ)process of obtainingand documenting evidence that installed equipment operateswithin predetermined limits when used in accordance with itsoperational procedures.3.1.9 performance qualification (PQ)process of obtain
22、ingand documenting evidence that the equipment, as installed andoperated in accordance with operational procedures, consis-tently performs in accordance with predetermined criteria andthereby yields product meeting its specification.3.1.10 process loada volume of material with a specifiedproduct loa
23、ding configuration irradiated as a single entity.3.1.11 processing categorygroup of different product thatcan be processed together.3.1.11.1 DiscussionProcessing categories can be basedon, for instance, composition, density or dose requirements.3.1.12 reference materialhomogeneous material of knownr
24、adiation absorption and scattering properties used to establishcharacteristics of the irradiation process, such as scanuniformity, depth-dose distribution, throughput rate, and repro-ducibility of dose delivery.3.1.13 routine monitoring positionposition where ab-sorbed dose is monitored during routi
25、ne processing to ensurethat the product is receiving the absorbed dose specified for theprocess.3.1.13.1 DiscussionThis position may be a location ofminimum or maximum dose in the process load or it may be analternate convenient location in, on or near the process loadwhere the relationship of the d
26、ose at this position with theminimum and maximum dose has been established.3.1.14 simulated productmaterial with attenuation andscattering properties similar to those of the product, material orsubstance to be irradiated.3.1.14.1 DiscussionSimulated product is used during irra-diator characterizatio
27、n 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 product is sometimes referred to as com-pensating dummy. When used for absorbed-dose mapping,simulated product is sometimes
28、 referred to as phantom mate-rial.3.2 Definitions of other terms used in this standard thatpertain to radiation measurement and dosimetry may be foundin Terminology E170. Definitions in E170 are compatible withICRU Report 60; that document, therefore, may be used as analternative reference.4. Signif
29、icance and Use4.1 This guide is one of a set of guides and practices thatprovide recommendations for properly implementing dosim-etry in radiation processing. In order to understand andeffectively use this and other dosimetry standards, considerfirst “Practice for Dosimetry in Radiation Processing,”
30、 ASTMPractice E2628, which describes the basic requirements thatapply when making absorbed dose measurements in accor-dance with theASTM E10.01 series of dosimetry standards. Inaddition, ASTM Practice E2628 provides guidance on theselection of dosimetry systems and directs the user to otherstandards
31、 that provide information on individual dosimetrysystems, calibration methods, uncertainty estimation and radia-tion processing applications.4.2 Radiation processing is carried out under fixed pathconditions where (a) a process load is automatically movedthrough the radiation field by mechanical mea
32、ns or (b)aprocess load is irradiated statically by manually placing prod-uct at predetermined positions before the process is started. Inboth cases the process is controlled in such a manner that theprocess load position(s) and orientation(s) are reproduciblewithin specified limits.NOTE 2Static irra
33、diation encompasses irradiation of the process loadusing either manual rotation, no rotation or automated rotation.4.3 Some radiation processing facilities that utilize a fixedconveyor path for routine processing may also characterize aregion within the radiation field for static radiation processin
34、g,sometimes referred to as “Off Carrier” processing.4.4 Many radiation processing applications require a mini-mum absorbed dose (to achieve a desired effect or to fulfill alegal requirement), and a maximum absorbed dose (to ensureE2303 1112that the product, material or substance still meets function
35、alspecifications or to fulfill a legal requirement).4.5 Information from the dose mapping is used to:4.5.1 Characterize the radiation process and assess thereproducibility of absorbed-dose values, which may be used aspart of operational qualification and performance qualification.4.5.2 Determine the
36、 spatial distribution of absorbed dosesand the zone(s) of maximum and minimum absorbed dosesthroughout a process load, which may consist of an actual orsimulated product.4.5.3 Establish the relationship between the dose at aroutine monitoring position and the dose within the minimumand maximum dose
37、zones established for a process load.4.5.4 Verify mathematical dose calculation methods. SeeASTM Guide E2232.4.5.5 Determine the effect of process interruptions on thedistribution of absorbed dose and the magnitude of the mini-mum and maximum doses.4.5.6 Assess the impact on the distribution of abso
38、rbed doseand the magnitude of the minimum and maximum dosesresulting from the transition from one process load to anotherwhere changes, for example, in product density or productloading pattern may occur.5. Prerequisites5.1 Prerequisites to Dose Mapping: Installation Qualifica-tion and Dosimetry Sys
39、tem Calibration:5.1.1 Prior to performing dose mapping for irradiator op-erational qualification (OQ) and performance qualification(PQ), confirm that installation qualification (IQ) is complete.5.1.1.1 For electron beam and X-ray irradiation facilities,IQ includes dosimetric testing to confirm the c
40、haracteristics ofthe beam (electron energy, average beam current, and ifapplicable, scan width and scan uniformity). Refer to ISO/ASTM 51431, 51608, 51818, 51649 and ISO 11137-1.5.1.1.2 For gamma irradiation facilities, dosimetric testingis not required during IQ; however, the activity of the source
41、and location of the individual components of the source shouldbe confirmed and documented. Refer to ISO/ASTM 51702 andISO 11137-1.5.1.2 Select an appropriate dosimetry system(s) for the dosemapping exercises. See 6.2.4.1 and ASTM Practice E2628 forguidance.5.2 Calibration of the Dosimetry System:5.2
42、.1 Prior to use, the dosimetry system, consisting ofdosimeters measurement instruments and their associated ref-erence standards, and procedures for the systems use, shouldbe calibrated in accordance with the users documented pro-cedure that specifies details of the calibration process andquality as
43、surance requirements. Calibration methods are de-scribed in ISO/ASTM 51261.NOTE 3A dosimetry system calibration obtained using irradiationconditions different from the conditions of use may be used for relativedose measurement applications. For example, an irradiation facility mayperform a lab-based
44、 calibration with subsequent verification using refer-ence standard dosimeters under the conditions of use.While dose mappingat the irradiation facility may be performed using dose values from thelab-based calibration (prior to completing the verification exercise) toassess the dose distribution and
45、 locations of minimum and maximumabsorbed dose, these dose measurements would be considered preliminary(i.e. relative) pending the outcome of the verification exercise.5.2.2 For the calibration of the instruments, and for theverification of instrument performance between calibrations,see ISO/ASTM 51
46、261 or instrument-specific operatingmanuals, or both.6. Dose Mapping6.1 Dose Mapping for Operational Qualification of theIrradiation Facility:6.1.1 As specified in ISO/ASTM Practices 51431, 51608,51649, 51702, and ISO 11137-1, perform irradiation facilitydose mapping to characterize the irradiator w
47、ith respect to thedose distribution and reproducibility of absorbed dose delivery.This should be performed in accordance with a formal valida-tion program, and should cover the operational range that willbe used in the irradiation of products.6.1.2 Perform irradiation facility dose mapping by placin
48、gdosimeters in a number of process loads of reference materialthat fills the container to its design volume limits. The numberof process loads to be dose mapped should be large enough (3or more) to determine the variability of dose. For thoseirradiation facilities that vary operating parameters whic
49、himpact dose distribution, dose mapping should be carried outover a range of selected operating parameters which cover theoperational limits to be used in the irradiation of products.6.1.2.1 Specific to Photon-based Facilities (gamma orX-ray)Material densities should be within the density rangefor which the irradiator is to be used.When processing multipledensities, dose mapping should be done for at least twodensities close to the minimum and maximum density to beprocessed to assess the impact density has on the magnitudeand distribution of the abs
