ASTM ISO/ASTM51276-19

• Abstract:

  SIGNIFICANCE AND USE; 4.1 The PMMA dosimetry system provides a means for measuring absorbed dose based on a change in optical absorbance. ; 4.2 PMMA dosimetry systems are commonly used in industrial radiation processing, for example in the sterilization of medical devices and the irradiation of foods.; SCOPE; 1.1 This is 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 generally used as a routine dosimetry system. ; 1.2 The PMMA dosimeter is classified as a Type II dosimeter on the basis of the complex effect of influence quantities (see ISO/ASTM Practice 52628). ; 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 ISO/ASTM 52628 “Practice for Dosimetry in Radiation Processing” for a PMMA dosimetry system. It is intended to be read in conjunction with ISO/ASTM Practice 52628. ; 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 × 10−2 to 1 × 107 Gy·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 appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. ; 1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

• Status: Published
• Publication Date: 31-Jan-2019
• ICS: 17.240 - Radiation measurements
• Technical Committee: E61 - Radiation Processing
• Drafting Committee: E61.02 - Dosimetry Systems

• Replaces: ASTM ISO/ASTM51276-12 - Standard Practice for Use of a Polymethylmethacrylate Dosimetry System
• Effective Date: 01-Feb-2019
• Refers: ASTM E3083-17 - Standard Terminology Relating to Radiation Processing: Dosimetry and Applications
• Effective Date: 01-Oct-2017
• Refers: ASTM E275-08 - Describing and Measuring Performance of Ultraviolet and Visible Spectrophotometers
• Effective Date: 15-Oct-2008
• Refers: ASTM E275-01 - Standard Practice for Describing and Measuring Performance of Ultraviolet, Visible, and Near-Infrared Spectrophotometers
• Effective Date: 10-Feb-2001
• Refers: ASTM E275-93 - Standard Practice for Describing and Measuring Performance of Ultraviolet, Visible, and Near-Infrared Spectrophotometers
• Effective Date: 10-Feb-2001

Overview

ASTM ISO/ASTM51276-19: Standard Practice for Use of a Polymethylmethacrylate Dosimetry System provides industry guidelines for the use of polymethylmethacrylate (PMMA) dosimetry systems in routine measurement of absorbed dose in materials exposed to photon or electron radiation. PMMA dosimetry is widely accepted for its reliability and practicality in industrial radiation processing. This standard outlines methods for accurate absorbed dose measurement, details influencing factors, and specifies recommended operational procedures, supporting compliance with broader international dosimetry standards.

Key Topics

• Scope of Application: The standard applies to PMMA dosimetry systems used for process control and routine measurement in the dose range 0.1 kGy to 150 kGy, with absorbed dose rates from 1 × 10⁻² to 1 × 10⁷ Gy·s⁻¹.
• Dosimeter Classification: PMMA dosimeters are classified as Type II due to their response characteristics and the influence of external factors (influence quantities).
• Measurement Principle: Absorbed dose determination is based on the quantifiable change in optical absorbance of PMMA. After irradiation, readings are made using calibrated spectrophotometers at specified wavelengths.
• Influence Quantities: Environmental and operational factors such as temperature, dose rate, light exposure, and humidity can impact dosimeter response and must be managed.
• System Calibration and Verification: Users must calibrate their PMMA dosimetry systems per ISO/ASTM 51261, verify performance of instruments and track batch-to-batch consistency.
• Operational Procedures: The standard details requirements for dosimeter handling, irradiation, post-irradiation processing, and absorbance measurement to ensure measurement integrity.

Applications

PMMA dosimetry systems are essential in several high-reliability industries where accurate and traceable radiation dose measurement is critical, including:

• Medical Device Sterilization: Ensures proper sterilization through precise absorbed dose measurement, supporting regulatory compliance in healthcare manufacturing.
• Food Irradiation: Monitors absorbed dose to ensure food products achieve required levels of pathogen reduction without compromising quality.
• Industrial Material Processing: Used in routine dose mapping, process validation, and quality control in polymer modification and composite material processing.
• Research Settings: Applied in radiation metrology labs for calibration, intercomparison studies, and development of improved dosimetric techniques.
• Routine Dosimetry: PMMA dosimeters, when calibrated against reference systems, provide a reliable method for ongoing process monitoring and dose mapping in continuous production environments.

Related Standards

For optimal quality assurance and reliable radiation processing, this standard should be used in conjunction with:

• ISO/ASTM 52628: Practice for Dosimetry in Radiation Processing - overarching requirements for conducting dosimetry.
• ISO/ASTM 51261: Practice for Selection and Calibration of Routine Dosimetry Systems for Radiation Processing.
• ISO/ASTM 51707: Guide for Estimating Measurement Uncertainty in Dosimetry for Radiation Processing.
• ASTM E170 / ASTM E3083: Terminology for radiation measurements and dosimetry.
• ISO 12749-4: Nuclear energy vocabulary relating to dosimetry for radiation processing.

Following ASTM ISO/ASTM51276-19 ensures reliable, repeatable, and auditable radiation processing and supports compliance with global trade and safety requirements in industries utilizing ionizing radiation.

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
ISO/ASTM 51276:2019(E)
Standard Practice for
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.
1. Scope 2. Referenced documents
2.1 ASTM Standards:
1.1 This is a practice for using polymethylmethacrylate
E275PracticeforDescribingandMeasuringPerformanceof
(PMMA) dosimetry systems to measure absorbed dose in
Ultraviolet and Visible Spectrophotometers
materials irradiated by photons or electrons in terms of
E3083Terminology Relating to Radiation Processing: Do-
absorbed dose to water. The PMMA dosimetry system is
simetry and Applications
generally used as a routine dosimetry system.
2.2 ISO/ASTM Standards:
1.2 The PMMA dosimeter is classified as a Type II dosim-
51261Practice for Calibration of Routine Dosimetry Sys-
eter on the basis of the complex effect of influence quantities
tems for Radiation Processing
(see ISO/ASTM Practice 52628).
51707Guide for Estimation of Measurement Uncertainty in
Dosimetry for Radiation Processing
1.3 This document is one of a set of standards that provides
52628Practice for Dosimetry in Radiation Processing
recommendations for properly implementing dosimetry in
52701Guide for Performance Characterization of Dosim-
radiation processing, and describes a means of achieving
eters and Dosimetry Systems for Use in Radiation Pro-
compliancewiththerequirementsofISO/ASTM52628“Prac-
cessing
tice for Dosimetry in Radiation Processing” for a PMMA
2.3 International Commission on Radiation Units and Mea-
dosimetry system. It is intended to be read in conjunction with
surements (ICRU) Reports:
ISO/ASTM Practice 52628.
ICRU Report 80Dosimetry Systems for Use in Radiation
1.4 This practice covers the use of PMMA dosimetry
Processing
systems under the following conditions:
ICRU Report 85aFundamental Quantities and Units for
1.4.1 the absorbed dose range is 0.1 kGy to 150 kGy.
Ionizing Radiation
−2 7 −1
1.4.2 the absorbed dose rate is1×10 to1×10 Gy·s .
2.4 ISO Standard:
12749-4Nuclearenergy—Vocabulary—Part4:Dosimetry
1.4.3 the photon energy range is 0.1 to 25 MeV.
for radiation processing
1.4.4 the electron energy range is 3 to 25 MeV.
2.5 Joint Committee for Guides in Metrology (JCGM)
1.5 This standard does not purport to address all of the
Reports:
safety concerns, if any, associated with its use. It is the
JCGM100:2008,GUM1995,withminorcorrectionsEvalu-
responsibility of the user of this standard to establish appro-
ation of measurement date - Guide to the Expression of
priate safety, health, and environmental practices and deter-
Uncertainty in Measurement
mine the applicability of regulatory limitations prior to use.
JCGM 200:2012, VIMInternational Vocabulary of Metrol-
1.6 This international standard was developed in accor-
ogy - Basic and General Concepts andAssociated Terms
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
For referenced ASTM and ISO/ASTM standards, visit the ASTM website,
Development of International Standards, Guides and Recom-
www.astm.org, or contact ASTM Customer Service at [e-mail]. For
mendations issued by the World Trade Organization Technical
Annual Book of ASTM Standards volume information, refer to the standard’s
Barriers to Trade (TBT) Committee.
Document Summary page on the ASTM website.
AvailablefromInternationalCommissiononRadiationUnits&Measurements,
7910 Woodmont Ave., Suite 400, Bethesda, MD 20814-3095, http://www.icru.org.
Available from International Organization for Standardization (ISO), ISO
This practice is under the jurisdiction of ASTM Committee E61 on Radiation Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier,
Processing and is the direct responsibility of Subcommittee E61.02 on Dosimetry Geneva, Switzerland, http://www.iso.org.
Systems, and is also under the jurisdiction of ISO/TC 85/WG 3. DocumentproducedbyWorkingGroup1oftheJointCommitteeforGuidesin
Current edition approved July 16, 2019. Published August 2019. Originally Metrology (JCGM WG1), Available free of charge at the BIPM website (http://
ε1
published as E1276–88. ASTM E1276-96 was adopted by ISO in 1998 with www.bipm.org).
the intermediate designation ISO 15558:1998(E). The present Fourth Edition of DocumentproducedbyWorkingGroup2oftheJointCommitteeforGuidesin
International Standard ISO/ASTM 51276:2019(E) is a major revision of the Third Metrology (JCGM WG2), Available free of charge at the BIPM website (http://
Edition of ISO/ASTM 51276:2012(E). www.bipm.org).
© ISO/ASTM International 2019 – All rights reserved
ISO/ASTM 51276:2019(E)
3. Terminology and the response to radiation is verified using appropriate
sampling and testing before release for packaging, and ulti-
3.1 Definitions:
mately for use.
3.1.1 dosimeter batch—quantity of dosimeters made from a
5.2 Ionizing radiation induces chemical reactions in the
specific mass of material with uniform composition, fabricated
material, which create or enhance absorption bands in the
in a single production run under controlled, consistent
visible or ultraviolet regions of the spectrum, or both. Optical
conditions, and having a unique identification code.
absorbancedeterminedatappropriatewavelengthswithinthese
3.1.2 dosimeter response (indication)—reproducible, quan-
radiation-induced absorption bands is quantitatively related to
tifiablechangeproducedinthedosimeterbyionizingradiation.
the absorbed dose. ICRU Report 80 provides information on
3.1.2.1 Discussion—The dosimeter response value
the scientific basis and historical development of the PMMA
(indication),obtainedfromoneormoremeasurements,isused
dosimetry systems in current use.
in the estimation of absorbed dose.
5.3 The difference between the specific absorbance of un-
3.1.2.2 Discussion—For PMMA dosimeters, the dosimeter
irradiated and irradiated PMMA is dependent upon the wave-
response value (indication) is obtained from measurement of
length of the light which is used to make the measurement.
the optical absorbance.
Typically, the manufacturer specifies the recommended wave-
3.1.3 dosimeter stock—partofadosimeterbatchheldbythe
length that optimizes sensitivity and post-irradiation stability.
user.
The wavelengths recommended for examples of commonly
used systems are given in Table A1.1.
3.1.4 polymethylmethacrylate (PMMA) dosimeter—piece of
specially selected or developed PMMA material, individually
6. Influence quantities
sealed by the manufacturer in an impermeable sachet that,
when irradiated, exhibits a characterizable change in specific
6.1 Factors other than absorbed dose which influence the
absorbance that can be related to absorbed dose.
dosimeter response are referred to as influence quantities and
3.1.4.1 Discussion—The piece of PMMA, when removed
are discussed in the following sections. (See also ISO/ASTM
from the sachet after irradiation, is also commonly referred to
Guide 52701.) Examples of such influence quantities are
as the dosimeter.
temperature and dose rate.
3.1.5 specific absorbance (k)—optical absorbance, A,ata
6.2 Pre-Irradiation Conditions:
λ
selected wavelength λ, divided by the optical path length, d:
6.2.1 Dosimeter Conditioning and Packaging—Pieces of
PMMA are pre-conditioned by the manufacturer to optimize
k5 A /d (1)
λ
water concentration, and sealed in impermeable aluminum foil
3.2 Definitions of other terms used in this standard that
laminate sachets to maintain that condition.
pertain to radiation measurement and dosimetry may be found
6.2.2 Time Since Manufacture—With appropriate
in ISO/ASTM Practice 52628. Other terms that pertain to
manufacturing,packagingandstorageconditions,theshelf-life
radiation measurement and dosimetry may be found inASTM
ofsometypesofPMMAdosimetershasbeenshowntoexceed
Terminology E3083 and ISO Terminology ISO 12749-4.
ten years (1).
Where appropriate, definitions used in these standards have
6.2.3 Temperature—Exposure to temperatures outside the
beenderivedfrom,andareconsistentwithdefinitionsinICRU
manufacturer’s recommended range should be minimized to
Report 85a, and general metrological definitions given in the
reduce the potential for adverse effects on dosimeter response.
VIM.
6.2.4 Relative Humidity—The effect of humidity is elimi-
nated by the isolation provided by the sachet.
4. Significance and use
6.2.5 Exposure to Light—The effect of light exposure is
4.1 The PMMA dosimetry system provides a means for
eliminated by the isolation provided by the sachet.
measuring absorbed dose based on a change in optical absor-
6.3 Conditions during Irradiation:
bance.
6.3.1 Irradiation Temperature—the dosimeter response is
4.2 PMMAdosimetrysystemsarecommonlyusedinindus-
affected by temperature and shall be characterized.
trial radiation processing, for example in the sterilization of
6.3.2 Absorbed-Dose Rate—the dosimeter response is af-
medical devices and the irradiation of foods.
fected by the absorbed-dose rate and shall be characterized.
6.3.3 Dose Fractionation—the dosimeter response may be
5. Overview
affectedbyincrementalexposuresandshouldbecharacterized.
6.3.4 Relative Humidity—the effect of humidity is elimi-
5.1 PMMA dosimeters may be manufactured by various
nated by the isolation provided by the sachet.
methods. For example, the raw material has historically been
6.3.5 Exposure to Light—theeffectoflightexposure,ifany,
cast,extruded,orinjectionmolded.Fundamentally,ingredients
is eliminated by the isolation provided by the sachet.
required for the promotion and control of polymerization and
stability, and, in the case of dyed dosimeters, specified quan-
titiesofdyesappropriatefortherequiredrangeofresponse,are
dissolved in methylmethacrylate, which is then polymerized.
Theboldfacenumbersinparenthesesrefertothebibliographyattheendofthis
The material is then conditioned to adjust the water content, practice.
© ISO/ASTM International 2019 – All rights reserved
ISO/ASTM 51276:2019(E)
6.3.6 Radiation Energy—the dosimeter response is depen- 7.1.4.1 Means of verifying thickness gauge calibration, for
dent upon the radiation energy and the dosimeters shall be example through the use of certified thickness gauge blocks,
irradiated for calibration under the conditions of use. exceeding the range of thicknesses encountered.
6.4 Post-Irradiation Conditions: 7.2 Measurement Management System, including the do-
6.4.1 Time—the time between irradiation and dosimeter
simeter batch calibration curve resulting from calibration
reading shall be standardized and should conform to the according to ISO/ASTM Practice 51261, and the procedures
manufacturer’s recommendations.
for use.
6.4.2 Temperature—Exposure to temperatures outside the
7.3 Performance Verification of Instrumentation:
manufacturer’s recommended range should be minimized to
7.3.1 At prescribed time intervals, and whenever there are
reduce the potential for adverse effects on dosimeter response.
indications of poor performance during periods of use, the
6.4.3 Conditioning Treatment—Post-irradiation treatment is
wavelength and absorbance scales of the spectrophotometer
not applicable.
shall be checked at or near the analysis wavelength, and the
6.4.4 Relative Humidity—Prior to opening the sachet, the
resultsdocumented.Thisinformationshouldbecomparedwith
effectofhumidityiseliminatedbytheisolationprovidedbythe
the instrument specifications to verify adequate performance,
sachet.
and the result documented. (See ASTM Practice E275.)
6.4.5 Exposure to Light—Prior to opening the sachet, any
7.3.2 At prescribed time intervals the calibration of the
effect of light exposure is eliminated by the isolation provided
thickness gauge shall be checked and the result documented.
by the sachet.
The thickness gauge shall also be checked before, during, and,
NOTE 1—Two categories of post-irradiation change are of concern
if considered appropriate, after use, to ensure reproducibility
when devising a practical operational protocol for the use of dosimeters:
the changes which occur if the sachet is left unopened; and those which and absence of zero drift.
occur after it is opened. It is good practice to assess the post-irradiation
change of dosimeters under both of these conditions. Examples of results
8. Incoming dosimeter stock assessment
obtained by a manufacturer are given in (2).
8.1 Aprotocolshallbeestablishedforthepurchase,receipt,
6.5 Response Measurement Conditions:
acceptance and storage of dosimeters.
6.5.1 ExposuretoLight—Afteropeningthesachet,exposure
to light may affect the response of the dosimeter. Users should
8.2 For dosimeters received, the user shall perform an
follow manufacturer’s recommended practices.
incoming inspection of a representative sample to verify, for
6.5.2 Temperature—Exposure to temperatures outside the
example, batch designation against the manufacturer’s
manufacturer’s recommended range should be minimized to
certification, sachet integrity, and that the sample’s thickness
reduce the potential for adverse effects on dosimeter response.
range, pre-irradiation absorbance, and radiation response, are
6.5.3 Relative Humidity—After opening the sachet, pro-
within documented specifications.
longedexposuretoextremehumidityconditionsmayaffectthe
8.3 Retain sufficient dosimeters for additional
responseofthedosimeter.Therefore,thetimebetweenopening
investigations, or for use during verification, or recalibration.
the sachet and dosimeter reading should be minimized.
6.5.4 Handling—Handle dosimeter by its edges. Skin oils, 8.4 Store dosimeters according to the manufacturer’s writ-
dirt and debris on the surface of dosimeters that are perpen- ten recommendations, or as justified by published data or
dicular to the analyzing light beam, may affect the absorbance experience.
of light, therefore impacting the dose measurement. NOTE 2—For some industries or uses of PMMAdosimeters, where the
dose delivered to product is a defined specification, the monitoring and
documentation of storing conditions is recommended in order to prevent
7. Dosimetry system and its verification
storage conditions being a cause of influence quantities.
7.1 Components of the PMMA Dosimetry System—The
following are components of PMMA dosimetry systems:
9. Calibration
7.1.1 Polymethylmethacrylate Dosimeters.
9.1 Prior to use of each batch of dosimeters, the dosimetry
7.1.2 Calibrated Spectrophotometer (or an equivalent
system shall be calibrated in accordance with the user’s
instrument), capable of measuring optical absorbance at the
procedures, which shall detail the calibration process and
analysis wavelength and having documentation specifying
qualityassurancerequirementsincompliancewithISO/ASTM
analysis wavelength range, accuracy of wavelength selection
Practice 51261.
and absorbance determination, spectral bandwidth, and stray
light rejection.
9.2 The user’s dosimetry sys
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
ISO/ASTM 51276:2012(E)
ISO/ASTM 51276 − 2019(E)
Standard Practice for
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.
1. Scope
1.1 This is 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 generally used
as a routine dosimetry system.
1.2 The PMMA dosimeter is classified as a Type II dosimeter on the basis of the complex effect of influence quantities (see
ASTMISO/ASTM Practice E2628).52628).
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 ASTMISO/ASTM E262852628 “Practice for
Dosimetry in Radiation Processing” for a PMMA dosimetry system. It is intended to be read in conjunction with ASTMISO/ASTM
E2628.Practice 52628.
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.
−2 7 −1
1.4.2 the absorbed dose rate is 1 × 10 to 1 × 10 Gy·s .
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 appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced documents
2.1 ASTM Standards:
E170 Terminology Relating to Radiation Measurements and Dosimetry
E275 Practice for Describing and Measuring Performance of Ultraviolet and Visible Spectrophotometers
E2628E3083 Practice for Dosimetry in Radiation ProcessingTerminology Relating to Radiation Processing: Dosimetry and
Applications
E2701 Guide for Performance Characterization of Dosimeters and Dosimetry Systems for Use in Radiation Processing
2.2 ISO/ASTM Standards:
51261 GuidePractice for Selection and Calibration of Routine Dosimetry Systems for Radiation Processing
51707 Guide for Estimating Uncertainties Estimation of Measurement Uncertainty in Dosimetry for Radiation Processing
52628 Practice for Dosimetry in Radiation Processing
52701 Guide for Performance Characterization of Dosimeters and Dosimetry Systems for Use in Radiation Processing
This practice is under the jurisdiction of ASTM Committee E61 on Radiation Processing and is the direct responsibility of Subcommittee E61.02 on Dosimetry Systems,
and is also under the jurisdiction of ISO/TC 85/WG 3.
ε1
Current edition approved Feb. 22, 2012. July 16, 2019. Published July 2012August 2019. Originally published as E 1276 – 88. ASTM E 1276 - 96 was adopted by ISO
in 1998 with the intermediate designation ISO 15558:1998(E). The present ThirdFourth Edition of International Standard ISO/ASTM 51276:2012(E)51276:2019(E) is a major
revision of the SecondThird Edition of ISO/ASTM 51276:2002(E).51276:2012(E).
For referenced ASTM and ISO/ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book
of ASTM Standards volume information, refer to the standard’s Document Summary page on the ASTM website.
© ISO/ASTM International 2019 – All rights reserved
ISO/ASTM 51276:2019(E)
2.3 International Commission on Radiation Units and Measurements (ICRU) Reports:
ICRU Report 60 Fundamental Quantities and Units for Ionizing Radiation
ICRU Report 80 Dosimetry Systems for Use in Radiation Processing
ICRU Report 85a Fundamental Quantities and Units for Ionizing Radiation
2.4 ISO Standard:
12749-4 Nuclear energy — Vocabulary — Part 4: Dosimetry for radiation processing
2.5 ISO Joint Committee for Guides in Metrology (JCGM) Reports:
GUMJCGM 100:2008, GUM 1995, with minor corrections Evaluation of measurement date - Guide to the Expression of
Uncertainty in Measurement, 1995.Measurement
JCGM 200:2012, VIM International Vocabulary of Metrology - Basic and General Terms in Metrology, 2008Concepts and
Associated Terms
3. Terminology
3.1 Definitions:
3.1.1 calibration curve—expression of the relation between indication and corresponding measured quantity value (VIM).
3.1.1.1 Discussion—
in radiation processing dosimetry standards, the term dosimeter response is generally used rather than “indication”. Thus, a
calibration curve is an expression of the relation between the dosimeter response and the corresponding measured quantity value.
3.1.2 dosimeter—a device that, when irradiated, exhibits a quantifiable change that can be related to absorbed dose in a given
material using appropriate measurement instruments and procedures.
3.1.1 dosimeter batch—quantity of dosimeters made from a specific mass of material with uniform composition, fabricated in
a single production run under controlled, consistent conditions, and having a unique identification code.
3.1.2 dosimeter response—response (indication)—reproducible, quantifiable effectchange produced in the dosimeter by ionizing
radiation.
NOTE 1—For PMMA dosimeters, the specific absorbance is the dosimeter response.
3.1.2.1 Discussion—
The dosimeter response value (indication), obtained from one or more measurements, is used in the estimation of absorbed dose.
3.1.2.2 Discussion—
For PMMA dosimeters, the dosimeter response value (indication) is obtained from measurement of the optical absorbance.
3.1.3 dosimeter stock—part of a dosimeter batch held by the user.
3.1.6 measurement management system—set of interrelated or interacting elements necessary to achieve metrological
confirmation and continual control of measurement processes.
3.1.4 polymethylmethacrylate (PMMA) dosimeter—piece of specially selected or developed PMMA material, individually
sealed by the manufacturer in an impermeable sachet, that during exposure to ionizing radiation sachet that, when irradiated,
exhibits a characterizable change in specific optical absorbance as a function of absorbance that can be related to absorbed dose.
NOTE 2—The piece of PMMA, when removed from the sachet after irradiation, is also commonly referred to as the dosimeter.
3.1.4.1 Discussion—
The piece of PMMA, when removed from the sachet after irradiation, is also commonly referred to as the dosimeter.
Available from International Commission on Radiation Units and& Measurements, 7910 Woodmont Ave., Suite 800,400, Bethesda, MD 20814, U.S.A.20814-3095,
http://www.icru.org.
Available from International Organization for Standardization (ISO), 1, ch. de la Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland, http://www.iso.orgISO
Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva, Switzerland, http://www.iso.org.
Document produced by Working Group 1 of the Joint Committee for Guides in Metrology (JCGM WG1), Available free of charge at the BIPM website
(http://www.bipm.org).
Document produced by Working Group 2 of the Joint Committee for Guides in Metrology (JCGM WG2), Available free of charge at the BIPM website
(http://www.bipm.org).
© ISO/ASTM International 2019 – All rights reserved
ISO/ASTM 51276:2019(E)
3.1.8 reference–standard dosimetry system—dosimetry system, generally having the highest metrological quality available at a
given location or in a given organization, from which measurements made there are derived.
3.1.9 response—see dosimeter response.
3.1.10 routine dosimetry system—dosimetry system calibrated against a reference standard dosimetry system and used for
routine absorbed dose measurements, including dose mapping and process monitoring.
3.1.5 specific absorbance (k)—optical absorbance, A , at a selected wavelength λ, divided by the optical path length, d:
λ
k 5 A /d (1)
λ
3.2 Definitions of other terms used in this practicestandard that pertain to radiation measurement and dosimetry may be found
in ISO/ASTM Practice 52628. Other terms that pertain to radiation measurement and dosimetry may be found in ASTM
Terminology E170E3083. Definitions and ISO Terminology ISO 12749-4. Where appropriate, definitions used in E170 are
compatible with ICRU Report 60; that document, therefore, may be used as an alternative reference.these standards have been
derived from, and are consistent with definitions in ICRU Report 85a, and general metrological definitions given in the VIM.
4. Significance and use
4.1 The PMMA dosimetry system provides a means for measuring absorbed dose based on a change in optical absorbance.
4.2 PMMA dosimetry systems are commonly used in industrial 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 methods. For example, the raw material has historically been cast,
extruded, or injection molded. Fundamentally, ingredients required for the promotion and control of polymerization and stability,
and, in the case of dyed dosimeters, specified quantities of dyes appropriate for the required range of response, are dissolved in
methylmethacrylate, which is then polymerized. The material is then conditioned to adjust the water content, and the response to
radiation is verified using appropriate sampling and testing before release for packaging, and ultimately for use.
5.2 Ionizing radiation induces chemical reactions in the material, which create or enhance absorption bands in the visible
and/oror ultraviolet regions of the spectrum. spectrum, or both. Optical absorbance determined at appropriate wavelengths within
these radiation-induced absorption bands is quantitatively related to the absorbed dose. ICRU Report 80 provides information on
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 wavelength
of the light which is used to make the measurement. Typically, the manufacturer specifies the recommended wavelength that
optimizes sensitivity and post-irradiation stability. The wavelengths recommended for examples of commonly used systems are
given in Table A1.1.
6. Influence quantities
6.1 Factors other than absorbed dose which influence the dosimeter response are referred to as influence quantities and are
discussed in the following sections. (See also ASTMISO/ASTM Guide E2701.)52701.) Examples of such influence quantities are
temperature and dose rate.
6.2 Pre-Irradiation Conditions:
6.2.1 Dosimeter Conditioning and Packaging—Pieces of PMMA are pre-conditioned by the manufacturer to optimize water
concentration, and sealed in impermeable aluminum foil laminate sachets to maintain that condition.
6.2.2 Time Since Manufacture—With appropriate manufacturing, packaging and storage conditions, the shelf-life of some types
of PMMA dosimeters has been shown to exceed ten years (1).
6.2.3 Temperature—Exposure to temperatures outside the manufacturer’s recommended range should be minimized to reduce
the potential for adverse effects on dosimeter response.
6.2.4 Relative Humidity—The effect of humidity is eliminated by the isolation provided by the sachet.
6.2.5 Exposure to Light—The effect of light exposure is eliminated by the isolation provided by the sachet.
6.3 Conditions during Irradiation:
6.3.1 Irradiation Temperature—the dosimeter response is affected by temperature and shall be characterized.
6.3.2 Absorbed-Dose Rate—the dosimeter response is affected by the absorbed-dose rate and shall be characterized.
6.3.3 Dose Fractionation—the dosimeter response may be affected by incremental exposures and should be characterized.
6.3.4 Relative Humidity—the effect of humidity is eliminated by the isolation provided by the sachet.
6.3.5 Exposure to Light—the effect of light exposure, if any, is eliminated by the isolation provided by the sachet.
The boldface numbers in parentheses refer to the bibliography at the end of this practice.
© ISO/ASTM International 2019 – All rights reserved
ISO/ASTM 51276:2019(E)
6.3.6 Radiation Energy—the dosimeter response is dependent 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 Time—the time between irradiation and dosimeter reading shall be standardized and should conform to the manufacturer’s
recommendations.
6.4.2 Temperature—Exposure to temperatures outside the manufacturer’s recommended range should be minimized to reduce
the potential for adverse effects on dosimeter response.
6.4.3 Conditioning Treatment—Post-irradiation treatment is not applicable.
6.4.4 Relative Humidity—Prior to opening the sachet, the effect of humidity is eliminated by the isolation provided by the
sachet.
6.4.5 Exposure to Light—Prior to opening the sachet, any effect of light exposure is eliminated by the isolation provided by the
sachet.
NOTE 1—Two categories of post-irradiation change are of concern when devising a practical operational protocol for the use of dosimeters: the changes
which occur if the sachet is left unopened; and those which occur after it is opened. It is good practice to assess the post-irradiation change of dosimeters
under both of these conditions. Examples of results obtained by a manufacturer are given in (2).
6.5 Response Measurement Conditions:
6.5.1 Exposure to Light—After opening the sachet, exposure to light may affect the response of the dosimeter. Users should
follow manufacturer’s recommended practices.
6.5.2 Temperature—Exposure to temperatures outside the manufacturer’s recommended range should be minimized to reduce
the potential for adverse effects on dosimeter response.
6.5.3 Relative Humidity—After opening the sachet, prolonged exposure to extreme humidity conditions may affect the response
of the dosimeter. Therefore, the time between opening the sachet and dosimeter reading should be minimized.
6.5.4 Handling—Handle dosimeter by its edges. Skin oils, dirt and debris on the surface of dosimeters that are perpendicular
to the analyzing light beam, may affect the absorbance of light, therefore impacting the dose measurement.
7. Dosimetry system and its verification
7.1 Components of the PMMA Dosimetry System—The following are components of PMMA dosimetry systems:
7.1.1 Polymethylmethacrylate Dosimeters.
7.1.2 Calibrated Spectrophotometer (or an equivalent instrument), capable of measuring optical absorbance at the analysis
wavelength and having documentation specifying analysis wavelength range, accuracy of wavelength selection and absorbance
determination, spectral bandwidth, and stray light rejection.
7.1.2.1 Means of verifying the accuracy of optical absorbance-measurement, for example through the use of certified optical
absorption filters, covering more than the range of absorption encountered.
7.1.2.2 Means of verifying wavelength calibration, for example through the use of certified filters.
7.1.3 Holder, to position the dosimeter reproducibly in, and perpendicular to, the analyzing light beam.
7.1.4 Calibrated Thickness Gauge.
7.1.4.1 Means of verifying thickness gauge calibration, for example through the use of certified thickness gauge blocks,
exceeding the range of thicknesses encountered.
7.2 Measurement Management System, including the dosimeter batch calibration curve resulting from calibration according to
ISO/ASTM Practice 51261, and the procedures for use.
7.3 Performance Verification of Instrumentation:
7.3.1 At prescribed time intervals, and whenever there are indications of poor performance during periods of use, the
wavelength and absorbance scales of the spectrophotometer shall be checked at or near the analysis wavelength, and the results
documented. This information should be compared with the instrument specifications to verify adequate performance, and the
result documented. (See
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