Practice for use of a polymethylmethacrylate dosimetry system

ISO/ASTM 51276:2012 provides recommendations for properly implementing dosimetry in radiation processing. ISO/ASTM 51276:2012 specifies a practice for using polymethylmethacrylate (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 classified as a routine dosimetry system. The PMMA dosimeter is classified as a Type II dosimeter on the basis of the complex effect of influence quantities. ISO/ASTM 51276:2012 is applicable to the use of PMMA dosimetry systems under the following conditions: - the absorbed dose range is 0,1 kGy to 150 kGy; - the absorbed dose rate is 1 x 10−2 Gy·s−1 to 1 x 107 Gy·s−1; - the photon energy range is 0,1 MeV to 25 MeV; - the electron energy range is 3 MeV to 25 MeV.

Pratique de l'utilisation d'un système dosimétrique au polyméthylméthacrylate

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Publication Date
04-Oct-2012
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04-Oct-2012
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INTERNATIONAL ISO/ASTM
STANDARD 51276
Third edition
2012-07-15
Practice for use of a
polymethylmethacrylate dosimetry
system
Pratique de l’utilisation d’un système dosimétrique au
polyméthylméthacrylate
Reference number
ISO/ASTM 51276:2012(E)
© ISO/ASTM International 2012

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ISO/ASTM51276:2012(E)
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ii © ISO/ASTM International 2012– All rights reserved

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ISO/ASTM51276:2012(E)
Contents Page
1 Scope . 1
2 Referenced documents . 1
3 Terminology . 1
4 Significance and use . 2
5 Overview . 2
6 Influence quantities . 2
7 Dosimetry system and its verification . 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 . 5
Table A1.1 Basic properties of available PMMA dosimeters . 4
Table A1.2 Some suppliers of polymethylmethacrylate (PMMA) dosimeters . 4
© ISO/ASTM International 2012– All rights reserved iii

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ISO/ASTM51276:2012(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation 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. 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 technical 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 world’s largest voluntary standards development organizations with global
participation from affected 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 E10.01,
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 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, Nuclear energy, nuclear
technologies and radiological protection.
Annex A1 of this International Standard is for information only.
iv © ISO/ASTM International 2012– All rights reserved

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ISO/ASTM51276:2012(E)
An American National Standard
Standard Practice for
1
Use of a Polymethylmethacrylate Dosimetry System
This standard is issued under the fixed 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.
2
1. Scope 2.2 ISO/ASTM Standards:
51261 Guide for Selection and Calibration of Dosimetry
1.1 This is a practice for using polymethylmethacrylate
Systems for Radiation Processing
(PMMA) dosimetry systems to measure absorbed dose in
51707 Guide for Estimating Uncertainties in Dosimetry for
materials irradiated by photons or electrons in terms of
Radiation Processing
absorbed dose to water. The PMMA dosimetry system is
2.3 International Commission on Radiation Units and
classified as a routine dosimetry system.
3
Measurements (ICRU) Reports:
1.2 The PMMA dosimeter is classified as a Type II dosim-
ICRU Report 60 Fundamental Quantities and Units for
eter on the basis of the complex effect of influence quantities
Ionizing Radiation
(see ASTM Practice E2628).
ICRU Report 80 Dosimetry Systems for Use in Radiation
1.3 This document is one of a set of standards that provides
Processing
recommendations for properly implementing dosimetry in
4
2.4 ISO Reports:
radiation processing, and describes a means of achieving
GUM Guide to the Expression of Uncertainty in Measure-
compliance with the requirements of ASTM E2628 “Practice
ment, 1995.
forDosimetryinRadiationProcessing”foraPMMAdosimetry
VIM International Vocabulary of Basic and General Terms
system. It is intended to be read in conjunction with ASTM
in Metrology, 2008
E2628.
1.4 This practice covers the use of PMMA dosimetry
3. Terminology
systems under the following conditions:
3.1 Definitions:
1.4.1 the absorbed dose range is 0.1 kGy to 150 kGy.
−2 7 −1 3.1.1 calibration curve—expression of the relation between
1.4.2 the absorbed dose rate is 1 3 10 to 1 3 10 Gy·s .
indication and corresponding measured quantity value (VIM).
1.4.3 the photon energy range is 0.1 to 25 MeV.
3.1.1.1 Discussion—in radiation processing dosimetry stan-
1.4.4 the electron energy range is 3 to 25 MeV.
dards,theterm dosimeter responseisgenerallyusedratherthan
1.5 This standard does not purport to address all of the
“indication”. Thus, a calibration curve is an expression of the
safety concerns, if any, associated with its use. It is the
relationbetweenthedosimeterresponseandthecorresponding
responsibility of the user of this standard to establish appro-
measured quantity value.
priate safety and health practices and determine the applica-
3.1.2 dosimeter—a device that, when irradiated, exhibits a
bility of regulatory limitations prior to use.
quantifiable change that can be related to absorbed dose in a
2. Referenced documents givenmaterialusingappropriatemeasurementinstrumentsand
2
procedures.
2.1 ASTM Standards:
3.1.3 dosimeter batch—quantity of dosimeters made from a
E170 TerminologyRelatingtoRadiationMeasurementsand
specific mass of material with uniform composition, fabricated
Dosimetry
in a single production run under controlled, consistent condi-
E275 Practice for Describing and Measuring Performance
tions, and having a unique identification code.
of Ultraviolet and Visible Spectrophotometers
3.1.4 dosimeter response—reproducible, quantifiable effect
E2628 Practice for Dosimetry in Radiation Processing
produced in the dosimeter by ionizing radiation.
E2701 Guide for Performance Characterization of Dosim-
etersandDosimetrySystemsforUseinRadiationProcess-
NOTE 1—For PMMAdosimeters, the specific absorbance is the dosim-
ing eter response.
3.1.5 dosimeter stock—partofadosimeterbatchheldbythe
1
user.
This practice is under the jurisdiction of ASTM Committee E10 on Nuclear
Technology and Applications and is the direct responsibility of Subcommittee 3.1.6 measurement management system—set of interrelated
E10.01 on Radiation Processing: Dosimetry andApplications, and is also under the
or interacting elements necessary to achieve metrological
jurisdiction of ISO/TC 85/WG 3.
confirmation and continual control of measurement processes.
Current edition approved Feb. 22, 2012. Published July 2012. Originally
´1
published as E1276–88. ASTM E1276-96 was adopted by ISO in 1998 with
the intermediate designation ISO 15558:1998(E). The present Third Edition of
InternationalStandardISO/ASTM51276:2012(E)isamajorrevisionoftheSecond
3
Edition of ISO/ASTM 51276:2002(E). Available from International Commission on Radiation Units and Measure-
2
For referenced ASTM and ISO/ASTM standards, visit the ASTM website, ments, 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814, U.S.A.
4
www.astm.org, or contact ASTM Customer Service at service@astm.org. For Available from International Organization for Standardization (ISO), 1, ch. de
Annual Book of ASTM Standards volume information, refer to the standard’s la Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland, http://
Document Summary page on the ASTM website. www.iso.org
© ISO/ASTM International 2012– All rights reserved
1

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ISO/ASTM51276:2012(E)
3.1.7 polymethylmethacrylate (PMMA) dosimeter—pieceof Typically, the manufacturer specifies the recommended wave-
specially selected or developed PMMA material, individually length that optimizes sensitivity and post-irradiation stability.
sealed by the manufacturer in an impermeable sachet, that The wavelengths recommended for examples of commonly
duringexposuretoionizingradiationexhibitsacharacterizable used systems are given in Table A1.1.
changeinspecificopticalabsorbanceasafunctionofabsorbed
dose.
6. Influence quantities
6.1 Factors other than absorbed dose which influence the
NOTE 2—The piece of PMMA, when removed from the sachet after
irradiation, is also commonly referred to as the dosimeter. dosimeter response are referred to as influence quantities and
arediscussedinthefollowingsections.(SeealsoASTMGuide
3.1.8 reference–standard dosimetry system—dosimetry sys-
E2701.) Examples of such influence quantities are temperature
tem, generally having the highest metrological quality avail-
and dose rate.
able at a given location or in a given organization, from which
6.2 Pre-Irradiation Conditions:
measurements made there are derived.
6.2.1 Dosimeter Conditioning and Packaging—Pieces of
3.1.9 response—see dosimeter response.
PMMA are pre-conditioned by the manufacturer to optimize
3.1.10 routine dosimetry system—dosimetry system cali-
water concentration, and sealed in impermeable aluminum foil
brated against a reference standard dosimetry system and used
laminate sachets to maintain that condition.
for routine absorbed dose measurements, including dose map-
6.2.2 Time Since Manufacture—With appropriate manufac-
ping and process monitoring.
turing,packagingandstorageconditions,theshelf-lifeofsome
3.1.11 specific absorbance (k)—optical absorbance, A ,ata
l
typesofPMMAdosimetershasbeenshowntoexceedtenyears
selected wavelength l, divided by the optical path length, d:
5
(1).
k 5 A /d (1)
l
6.2.3 Temperature—Exposure to temperatures outside the
3.2 Definitions of other terms used in this practice that
manufacturer’s recommended range should be minimized to
pertain to radiation measurement and dosimetry may be found
reduce the potential for adverse effects on dosimeter response.
inASTM Terminology E170. Definitions in E170 are compat-
6.2.4 Relative Humidity—The effect of humidity is elimi-
ible with ICRU Report 60; that document, therefore, may be
nated by the isolation provided by the sachet.
used as an alternative reference.
6.2.5 Exposure to Light—The effect of light exposure is
eliminated by the isolation provided by the sachet.
4. Significance and use
6.3 Conditions during Irradiation:
4.1 The PMMA dosimetry system provides a means for
6.3.1 Irradiation Temperature—the dosimeter response is
measuring absorbed dose based on a change in optical absor-
affected by temperature and shall be characterized.
bance.
6.3.2 Absorbed-Dose Rate—the dosimeter response is af-
4.2 PMMAdosimetrysystemsarecommonlyusedinindus-
fected by the absorbed-dose rate and shall be characterized.
trial radiation processing, for example in the sterilization of
6.3.3 Dose Fractionation—the dosimeter response may be
medical devices and the irradiation of foods.
affectedbyincrementalexposuresandshouldbecharacterized.
6.3.4 Relative Humidity—the effect of humidity is elimi-
5. Overview
nated by the isolation provided by the sachet.
5.1 PMMA dosimeters may be manufactured by various
6.3.5 Exposure to Light—theeffectoflightexposure,ifany,
methods. For example, the raw material has historically been
is eliminated by the isolation provided by the sachet.
cast,extruded,orinjectionmolded.Fundamentally,ingredients
6.3.6 Radiation Energy—the dosimeter response is depen-
required for the promotion and control of polymerization and
dent upon the radiation energy and the dosimeters shall be
stability, and, in the case of dyed dosimeters, specified quan-
irradiated for calibration under the conditions of use.
titiesofdyesappropriatefortherequiredrangeofresponse,are
6.4 Post-Irradiation Conditions:
dissolved in methylmethacrylate, which is then polymerized.
6.4.1 Time—the time between irradiation and dosimeter
The material is then conditioned to adjust the water content,
reading shall be standardized and should conform to the
and the response to radiation is verified using appropriate
manufacturer’s recommendations.
sampling and testing before release for packaging, and ulti-
6.4.2 Temperature—Exposure to temperatures outside the
mately for use.
manufacturer’s recommended range should be minimized to
5.2 Ionizing radiation induces chemical reactions in the
reduce the potential for adverse effects on dosimeter response.
material, which create or enhance absorption bands in the
6.4.3 Conditioning Treatment—Post-irradiation treatment is
visible and/or ultraviolet regions of the spectrum. Optical
not applicable.
absorbancedeterminedatappropriatewavelengthswithinthese
6.4.4 Relative Humidity—Prior to opening the sachet, the
radiation-induced absorption bands is quantitatively related to
effectofhumidityiseliminatedbytheisolationprovidedbythe
the absorbed dose. ICRU Report 80 provides information on
sachet.
the scientific basis and historical development of the PMMA
dosimetry systems in current use.
5.3 The difference between the specific absorbance of un-
irradiated and irradiated PMMA is dependent upon the wave- 5
Theboldfacenumbersinparenthesesrefertothebibliographyattheendofthis
length of the light which is used to make the measurement. practice.
© ISO/ASTM International 2012– All rights reserved
2

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ISO/ASTM51276:2012(E)
6.4.5 Exposure to Light—Prior to opening the sachet, any if considered appropriate, after use, to ensure reproducibility
effect of light exposure is eliminated by the isolation provided and absence of zero drift.
by the sachet.
8. Incoming dosimeter stock assessment
NOTE 3—Two categories of post-irradiation change are of concern
8.1 Aprotocolshallbeestablishedforthep
...

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