1、Practice for use of a polymethylmethacrylate dosimetry system Pratique de lutilisation dun systme dosimtrique au polymthylmthacrylate INTERNATIONAL ISO/ASTM STANDARD 51276 Third edition 2012-07-15 Reference number ISO/ASTM 51276:2012(E) ISO/ASTM International 2012PDF disclaimer This PDF le may conta
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5、addresses given below. ISO/ASTM International 2012 All rights reserved. Unless otherwise specied, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microlm, without permission in writing from either ISO at the
6、address below or ISOs member body in the country of the requester. In the United States, such requests should be sent to ASTM International. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. +41 22 749 01 11 Fax +41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org ASTM International, 1
7、00 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, USA Tel. +610 832 9634 Fax +610 832 9635 E-mail khooperastm.org Web www.astm.org Published in the United States ISO/ASTM51276:2012(E) ii ISO/ASTM International 2012 All rights reservedContents Page 1 Scope . 1 2 Referenced document
8、s . 1 3 Terminology 1 4 Signicance and use . 2 5 Overview 2 6 Inuence quantities . 2 7 Dosimetry system and its verication . 3 8 Incoming dosimeter stock assessment . 3 9 Calibration 3 10 Routine use 3 11 Documentation requirements . 4 12 Measurement uncertainty 4 13 Keywords 4 ANNEX 4 Bibliography
9、. 5 Table A1.1 Basic properties of available PMMA dosimeters . 4 Table A1.2 Some suppliers of polymethylmethacrylate (PMMA) dosimeters 4 ISO/ASTM51276:2012(E) iii ISO/ASTM International 2012 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federatio
10、n of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee.
11、 International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technic
12、al committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75% of the member bodies casting a vote. ASTM International is one of the worlds largest voluntary standards development organizations with global participation from a
13、ffected stakeholders. ASTM technical committees follow rigorous due process balloting procedures. A pilot project between ISO and ASTM International has been formed to develop and maintain a group of ISO/ASTM radiation processing dosimetry standards. Under this pilot project, ASTM Subcommittee E10.0
14、1, Dosimetry for Radiation Processing, is responsible for the development and maintenance of these dosimetry standards with unrestricted participation and input from appropriate ISO member bodies. Attention is drawn to the possibility that some of the elements of this document may be the subject of
15、patent rights. Neither ISO nor ASTM International shall be held responsible for identifying any or all such patent rights. International Standard ISO/ASTM 51276 was developed by ASTM Committee E10, Nuclear Technology and Applications, through Subcommittee E10.01, and by Technical Committee ISO/TC 85
16、, Nuclear energy, nuclear technologies and radiological protection. Annex A1 of this International Standard is for information only. ISO/ASTM51276:2012(E) iv ISO/ASTM International 2012 All rights reservedISO/ASTM51276:2012(E) An American National Standard Standard Practice for Use of a Polymethylme
17、thacrylate Dosimetry System 1 This standard is issued under the xed designation ISO/ASTM 51276; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. 1. Scope 1.1 This is a practice for using polymethylmethacr
18、ylate (PMMA) dosimetry systems to measure absorbed dose in materials irradiated by photons or electrons in terms of absorbed dose to water. The PMMA dosimetry system is classied as a routine dosimetry system. 1.2 The PMMA dosimeter is classied as a Type II dosim- eter on the basis of the complex eff
19、ect of inuence quantities (see ASTM Practice E2628). 1.3 This document is one of a set of standards that provides recommendations for properly implementing dosimetry in radiation processing, and describes a means of achieving compliance with the requirements of ASTM E2628 “Practice forDosimetryinRad
20、iationProcessing”foraPMMAdosimetry system. It is intended to be read in conjunction with ASTM E2628. 1.4 This practice covers the use of PMMA dosimetry systems under the following conditions: 1.4.1 the absorbed dose range is 0.1 kGy to 150 kGy. 1.4.2 the absorbed dose rate is 1 3 10 2 to 1 3 10 7 Gy
21、s 1 . 1.4.3 the photon energy range is 0.1 to 25 MeV. 1.4.4 the electron energy range is 3 to 25 MeV. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate safety and
22、 health practices and determine the applica- bility of regulatory limitations prior to use. 2. Referenced documents 2.1 ASTM Standards: 2 E170 TerminologyRelatingtoRadiationMeasurementsand Dosimetry E275 Practice for Describing and Measuring Performance of Ultraviolet and Visible Spectrophotometers
23、E2628 Practice for Dosimetry in Radiation Processing E2701 Guide for Performance Characterization of Dosim- etersandDosimetrySystemsforUseinRadiationProcess- ing 2.2 ISO/ASTM Standards: 2 51261 Guide for Selection and Calibration of Dosimetry Systems for Radiation Processing 51707 Guide for Estimati
24、ng Uncertainties in Dosimetry for Radiation Processing 2.3 International Commission on Radiation Units and Measurements (ICRU) Reports: 3 ICRU Report 60 Fundamental Quantities and Units for Ionizing Radiation ICRU Report 80 Dosimetry Systems for Use in Radiation Processing 2.4 ISO Reports: 4 GUM Gui
25、de to the Expression of Uncertainty in Measure- ment, 1995. VIM International Vocabulary of Basic and General Terms in Metrology, 2008 3. Terminology 3.1 Denitions: 3.1.1 calibration curveexpression of the relation between indication and corresponding measured quantity value (VIM). 3.1.1.1 Discussio
26、nin radiation processing dosimetry stan- dards,theterm dosimeter responseisgenerallyusedratherthan “indication”. Thus, a calibration curve is an expression of the relationbetweenthedosimeterresponseandthecorresponding measured quantity value. 3.1.2 dosimetera device that, when irradiated, exhibits a
27、 quantiable change that can be related to absorbed dose in a givenmaterialusingappropriatemeasurementinstrumentsand procedures. 3.1.3 dosimeter batchquantity of dosimeters made from a specic mass of material with uniform composition, fabricated in a single production run under controlled, consistent
28、 condi- tions, and having a unique identication code. 3.1.4 dosimeter responsereproducible, quantiable effect produced in the dosimeter by ionizing radiation. NOTE 1For PMMAdosimeters, the specic absorbance is the dosim- eter response. 3.1.5 dosimeter stockpartofadosimeterbatchheldbythe user. 3.1.6
29、measurement management systemset of interrelated or interacting elements necessary to achieve metrological conrmation and continual control of measurement processes. 1 This practice is under the jurisdiction of ASTM Committee E10 on Nuclear Technology and Applications and is the direct responsibilit
30、y of Subcommittee E10.01 on Radiation Processing: Dosimetry andApplications, and is also under the jurisdiction of ISO/TC 85/WG 3. Current edition approved Feb. 22, 2012. Published July 2012. Originally published as E127688. ASTM E1276-96 1 was adopted by ISO in 1998 with the intermediate designatio
31、n ISO 15558:1998(E). The present Third Edition of InternationalStandardISO/ASTM51276:2012(E)isamajorrevisionoftheSecond Edition of ISO/ASTM 51276:2002(E). 2 For referenced ASTM and ISO/ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.org. For Annu
32、al Book of ASTM Standards volume information, refer to the standards Document Summary page on the ASTM website. 3 Available from International Commission on Radiation Units and Measure- ments, 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814, U.S.A. 4 Available from International Organization for S
33、tandardization (ISO), 1, ch. de la Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland, http:/ www.iso.org 1 ISO/ASTM International 2012 All rights reserved 3.1.7 polymethylmethacrylate (PMMA) dosimeterpieceof specially selected or developed PMMA material, individually sealed by the manufa
34、cturer in an impermeable sachet, that duringexposuretoionizingradiationexhibitsacharacterizable changeinspecicopticalabsorbanceasafunctionofabsorbed dose. NOTE 2The piece of PMMA, when removed from the sachet after irradiation, is also commonly referred to as the dosimeter. 3.1.8 referencestandard d
35、osimetry systemdosimetry sys- tem, generally having the highest metrological quality avail- able at a given location or in a given organization, from which measurements made there are derived. 3.1.9 responsesee dosimeter response. 3.1.10 routine dosimetry systemdosimetry system cali- brated against
36、a reference standard dosimetry system and used for routine absorbed dose measurements, including dose map- ping and process monitoring. 3.1.11 specic absorbance (k)optical absorbance, A l ,ata selected wavelength l, divided by the optical path length, d: k 5 A l /d (1) 3.2 Denitions of other terms u
37、sed in this practice that pertain to radiation measurement and dosimetry may be found inASTM Terminology E170. Denitions in E170 are compat- ible with ICRU Report 60; that document, therefore, may be used as an alternative reference. 4. Signicance and use 4.1 The PMMA dosimetry system provides a mea
38、ns for measuring absorbed dose based on a change in optical absor- bance. 4.2 PMMAdosimetrysystemsarecommonlyusedinindus- trial radiation processing, for example in the sterilization of medical devices and the irradiation of foods. 5. Overview 5.1 PMMA dosimeters may be manufactured by various metho
39、ds. For example, the raw material has historically been cast,extruded,orinjectionmolded.Fundamentally,ingredients required for the promotion and control of polymerization and stability, and, in the case of dyed dosimeters, specied quan- titiesofdyesappropriatefortherequiredrangeofresponse,are dissol
40、ved in methylmethacrylate, which is then polymerized. The material is then conditioned to adjust the water content, and the response to radiation is veried using appropriate sampling and testing before release for packaging, and ulti- mately for use. 5.2 Ionizing radiation induces chemical reactions
41、 in the material, which create or enhance absorption bands in the visible and/or ultraviolet regions of the spectrum. Optical absorbancedeterminedatappropriatewavelengthswithinthese radiation-induced absorption bands is quantitatively related to the absorbed dose. ICRU Report 80 provides information
42、 on the scientic basis and historical development of the PMMA dosimetry systems in current use. 5.3 The difference between the specic absorbance of un- irradiated and irradiated PMMA is dependent upon the wave- length of the light which is used to make the measurement. Typically, the manufacturer sp
43、ecies the recommended wave- length that optimizes sensitivity and post-irradiation stability. The wavelengths recommended for examples of commonly used systems are given in Table A1.1. 6. Inuence quantities 6.1 Factors other than absorbed dose which inuence the dosimeter response are referred to as
44、inuence quantities and arediscussedinthefollowingsections.(SeealsoASTMGuide E2701.) Examples of such inuence quantities are temperature and dose rate. 6.2 Pre-Irradiation Conditions: 6.2.1 Dosimeter Conditioning and PackagingPieces of PMMA are pre-conditioned by the manufacturer to optimize water co
45、ncentration, and sealed in impermeable aluminum foil laminate sachets to maintain that condition. 6.2.2 Time Since ManufactureWith appropriate manufac- turing,packagingandstorageconditions,theshelf-lifeofsome typesofPMMAdosimetershasbeenshowntoexceedtenyears (1). 5 6.2.3 TemperatureExposure to tempe
46、ratures outside the manufacturers recommended range should be minimized to reduce the potential for adverse effects on dosimeter response. 6.2.4 Relative HumidityThe effect of humidity is elimi- nated by the isolation provided by the sachet. 6.2.5 Exposure to LightThe effect of light exposure is eli
47、minated by the isolation provided by the sachet. 6.3 Conditions during Irradiation: 6.3.1 Irradiation Temperaturethe dosimeter response is affected by temperature and shall be characterized. 6.3.2 Absorbed-Dose Ratethe dosimeter response is af- fected by the absorbed-dose rate and shall be character
48、ized. 6.3.3 Dose Fractionationthe dosimeter response may be affectedbyincrementalexposuresandshouldbecharacterized. 6.3.4 Relative Humiditythe effect of humidity is elimi- nated by the isolation provided by the sachet. 6.3.5 Exposure to Lighttheeffectoflightexposure,ifany, is eliminated by the isola
49、tion provided by the sachet. 6.3.6 Radiation Energythe dosimeter response is depen- dent upon the radiation energy and the dosimeters shall be irradiated for calibration under the conditions of use. 6.4 Post-Irradiation Conditions: 6.4.1 Timethe time between irradiation and dosimeter reading shall be standardized and should conform to the manufacturers recommendations. 6.4.2 TemperatureExposure to temperatures outside the manufacturers recommended rang
