ASTM ISO/ASTM51275-21

Standard Practice for Use of a Radiochromic Film Dosimetry System

SIGNIFICANCE AND USE
4.1 The radiochromic film dosimetry system provides a means for measuring absorbed dose based on radiation-induced change in color using spectrophotometers, densitometers or scanned images.  
4.2 Radiochromic film 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 radiochromic film dosimetry systems to measure absorbed dose in materials irradiated by photons or electrons in terms of absorbed dose to water. Radiochromic film dosimetry systems are generally used as routine dosimetry systems.  
1.2 The radiochromic film dosimeter is classified as a type II dosimeter on the basis of the complex effect of influence quantities (see ISO/ASTM 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 radiochromic film dosimetry system. It is intended to be read in conjunction with ISO/ASTM 52628.  
1.4 This practice covers the use of radiochromic film dosimetry systems under the following conditions:  
1.4.1 The absorbed dose range is 1 Gy to 150 kGy.  
1.4.2 The absorbed dose rate is 1 × 10-2 to 1 × 1013 Gy·s-1 (1-4).2  
1.4.3 The photon energy range is 0.1 to 50 MeV.  
1.4.4 The electron energy range is 70 keV to 50 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.

General Information

• Status: Published
• Publication Date: 30-Sep-2021
• ICS: 17.240 - Radiation measurements
• ICS: 37.040.25 - Radiographic films
• Technical Committee: E61 - Radiation Processing
• Drafting Committee: E61.02 - Dosimetry Systems

Relations

• Replaces: ASTM ISO/ASTM51275-13 - Standard Practice for Use of a Radiochromic Film Dosimetry System
• Effective Date: 01-Oct-2021

Overview

ASTM ISO/ASTM51275-21 is an international standard practice developed by ASTM for the use of radiochromic film dosimetry systems. This document provides protocols and recommendations for employing radiochromic film dosimeters to measure absorbed dose in materials irradiated by photons or electrons, primarily with reference to absorbed dose to water. Radiochromic film dosimetry systems are widely utilized as routine dosimetry tools in industrial radiation processing, supporting accurate monitoring and verification within irradiation facilities.

Radiochromic films undergo a quantifiable change in color when exposed to ionizing radiation. This color change can be measured using spectrophotometers, densitometers, or scanned images and correlated with radiation dose. The standard covers film dosimeter classification, practical usage, calibration, and quality assurance, aiding compliance with global best practices in dosimetry.

Key Topics

• Scope of Use: The standard applies to radiochromic film dosimetry systems within absorbed dose ranges from 1 Gy to 150 kGy and for dose rates of 1 × 10⁻² to 1 × 10¹³ Gy·s⁻¹. It is suitable for photon energies between 0.1 to 50 MeV and electron energies from 70 keV to 50 MeV.

• System Components:

  • Radiochromic film dosimeters: Flexible films that exhibit measurable optical absorbance changes post-irradiation.
  • Measurement instruments: Including spectrophotometers, densitometers, or image scanners, used to assess color changes.
  • Dosimeter holders and optional calibrated thickness gauges for consistent measurement.

• Calibration Requirements: Calibration must be undertaken per ISO/ASTM 51261, reflecting the influence of temperature, humidity, and other environmental factors encountered in use. Multiple calibration curves for different dose ranges can help manage measurement uncertainty.

• Influence Quantities: Dosimeter response can be affected by environmental conditions such as water content, temperature, humidity, dose rate, and exposure to light. Proper calibration and handling mitigate these effects.

• Routine Use and Verification: Procedures for inspecting incoming dosimeter stock, verifying system performance, and recording results as part of a measurement management system are clearly defined.

• Measurement Uncertainty: The standard mandates an estimation of uncertainty for all absorbed dose readings, referring to ISO/ASTM 51707 and GUM for detailed guidance.

Applications

Radiochromic film dosimetry finds widespread application in industries requiring precise and reliable measurement of ionizing radiation doses, including:

• Sterilization of medical devices: Ensures that medical products receive the required radiation dose for effective sterilization, supporting regulatory compliance.
• Food irradiation: Verifies absorbed doses to maintain quality and safety in treated food products.
• Routine monitoring in industrial radiation processing: Enables systematic dose mapping and process validation in irradiation facilities, supporting quality assurance programs.
• Process development and validation: Assures that new processes or equipment configurations deliver accurate doses for intended outcomes.

By providing comprehensive protocols and quality assurance steps, this standard supports reproducible, accurate, and traceable dose measurements crucial for safety and efficacy in radiation applications.

Related Standards

Several other international documents complement or are referenced by ASTM ISO/ASTM51275-21, including:

• ISO/ASTM 52628: Practice for Dosimetry in Radiation Processing
• ISO/ASTM 51261: Practice for Calibration of Routine Dosimetry Systems for Radiation Processing
• ISO/ASTM 51707: Guide for Estimating Uncertainties in Dosimetry for Radiation Processing
• ASTM E3083: Terminology Relating to Radiation Processing: Dosimetry and Applications
• ASTM E275: Practice for Describing and Measuring Performance of Ultraviolet and Visible Spectrophotometers

For practitioners in radiation processing, adherence to this standard and related documents ensures compliance with international best practices and helps facilitate trade by meeting quality and regulatory requirements.

Standards Content (Sample)

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.
Designation: 51275 − 21
Standard Practice for
Use of a Radiochromic Film Dosimetry System
This standard is issued under the fixed designation 51275; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced documents
1.1 This is a practice for using radiochromic film dosimetry
2.1 ASTM Standards:
systems to measure absorbed dose in materials irradiated by
E275 Practice for Describing and Measuring Performance of
photons or electrons in terms of absorbed dose to water.
Ultraviolet and Visible Spectrophotometers
Radiochromic film dosimetry systems are generally used as
E3083 Terminology Relating to Radiation Processing: Do-
routine dosimetry systems.
simetry and Applications
1.2 The radiochromic film dosimeter is classified as a type II
2.2 ISO/ASTM Standards:
dosimeter on the basis of the complex effect of influence
51261 Practice for Calibration of Routine Dosimetry Sys-
quantities (see ISO/ASTM 52628).
tems for Radiation Processing
1.3 This document is one of a set of standards that provides
51707 Guide for Estimating Uncertainties in Dosimetry for
recommendations for properly implementing dosimetry in
Radiation Processing
radiation processing, and describes a means of achieving
52628 Practice for Dosimetry in Radiation Processing
compliance with the requirements of ISO/ASTM 52628 “Prac-
52701 Guide for Performance Characterization of Dosim-
tice for Dosimetry in Radiation Processing” for a radiochromic
eters and Dosimetry Systems for Use in Radiation Pro-
film dosimetry system. It is intended to be read in conjunction
cessing
with ISO/ASTM 52628.
2.3 International Commission on Radiation Units and Mea-
1.4 This practice covers the use of radiochromic film
surements (ICRU) Reports:
dosimetry systems under the following conditions:
ICRU Report 85a Fundamental Quantities and Units for
1.4.1 The absorbed dose range is 1 Gy to 150 kGy.
-2 13
Ionizing Radiation
1.4.2 The absorbed dose rate is 1 × 10 to 1 × 10
-1 2
ICRU Report 80 Dosimetry Systems for Use in Radiation
Gy·s (1-4).
Processing
1.4.3 The photon energy range is 0.1 to 50 MeV.
1.4.4 The electron energy range is 70 keV to 50 MeV.
2.4 ISO/ASTM Standards:
1.5 This standard does not purport to address all of the 12749-4 Nuclear energy – Vocabulary – Part 4: Dosimetry
safety concerns, if any, associated with its use. It is the
for radiation processing
responsibility of the user of this standard to establish appro-
2.5 Joint Committee for Guides in Metrology (JCGM)
priate safety, health, and environmental practices and deter-
Reports:
mine the applicability of regulatory limitations prior to use.
JCGM 100:2008, GUM 1995, with minor corrections,
1.6 This international standard was developed in accor-
Evaluation of measurement data – Guide to the Expres-
dance with internationally recognized principles on standard-
sion of Uncertainty in Measurement
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee. 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
This practice is under the jurisdiction of ASTM Committee E61 on Radiation Document Summary page on the ASTM website.
Processing and is the direct responsibility of Subcommittee E61.02 on Dosimetry Available from the International Commission on Radiation Units and
Systems. Originally developed as a joint ASTM/ISO standard in conjunction with Measurements, 7910 Woodmont Ave., suite 800, Bethesda, MD 20814, USA.
ISO/TC 85/WG 3. Available from International Organization for Standardization (ISO), ISO
Current edition approved Oct. 1, 2021. Published May 2024. Originally approved Central Secretariat, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva,
in 1988. Last previous edition approved in 2013 as ISO/ASTM 51275:2013(E). Switzerland, https://www.iso.org.
DOI: 10.1520/51275-21. Document produced by Working Group 1 of the Joint Committee for Guides in
The boldface numbers in parentheses refer to the bibliography at the end of this Metrology (JCGM/WG 1). Available free of charge at the BIPM website (http://
standard. www.bipm.org).
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
51275 − 21
JCGM 200:2008, VIM, International vocabulary of metrol- 4. Significance and use
ogy – Basis and general concepts and associated terms
4.1 The radiochromic film dosimetry system provides a
means for measuring absorbed dose based on radiation-induced
3. Terminology
change in color using spectrophotometers, densitometers or
scanned images.
3.1 Definitions:
3.1.1 dosimeter batch—quantity of dosimeters made from a
4.2 Radiochromic film dosimetry systems are commonly
specific mass of material with uniform composition, fabricated
used in industrial radiation processing, for example in the
in a single production run under controlled, consistent
sterilization of medical devices and the irradiation of foods.
conditions, and having a unique identification code.
5. Overview
3.1.2 dosimeter response—reproducible, quantifiable effect
5.1 Radiochromic film dosimeters are manufactured by
produced in the dosimeter by ionizing radiation.
various methods to produce freestanding or coated films, which
3.1.2.1 Discussion—For radiochromic film dosimeters, the
are flexible and transparent. They are generally supplied as
absorbance, specific absorbance or specific net absorbance is
small squares, strips, or long rolls or sheets that can be cut into
the dosimeter response.
a convenient size for dosimetry purposes. The response of the
dosimeters may be influenced by water content, irradiation
3.1.3 dosimeter stock—part of a dosimeter batch held by the
temperature, post-irradiation time to measurement, and other
user.
potential influence quantities that need to be taken into
3.1.4 measurement management system—a set of interre-
account. Many commercially available dosimeters are supplied
lated or interacting elements necessary to achieve metrological
in light- and vapor-tight packages, which effectively protect
confirmation and continual control of measurement processes.
against light and changes in ambient humidity. The dosimeters
3.1.5 radiochromic film dosimeter—specially prepared film should be calibrated under irradiation conditions that are
containing ingredients that undergo change in optical absor- similar to those in which they will be used.
bance under ionizing radiation, which can be related to
5.2 Ionizing radiation induces chemical reactions in the
absorbed dose to water.
material, which create or enhance absorption bands in the
visible or ultraviolet regions, or both, of the optical spectrum.
3.1.6 reference standard dosimetry system—dosimetry
Absorbance determined at appropriate wavelengths within
system, generally having the highest metrological quality
these radiation-induced absorption bands is quantitatively re-
available at a given location or in a given organization, from
lated to the absorbed dose. ICRU Report 80 provides technical
which measurements made there are derived.
information and historical development of the radiochromic
3.1.7 response—see dosimeter response.
film dosimetry systems in current use.
3.1.8 routine dosimetry system—dosimetry system cali-
5.3 The radiation-induced change in absorbance of the
brated against a reference standard dosimetry system and used
radiochromic film depends on the wavelength of the light
for routine absorbed dose measurements, including dose map-
which is used to make the measurement.
ping and process monitoring.
6. Influence quantities
3.1.9 specific absorbance (k)—optical absorbance, A , at a
λ
6.1 Factors other than absorbed dose which influence the
selected wavelength λ, divided by the optical path length, d:
dosimeter response are referred to as influence quantities. (See
k 5 A ⁄d (1)
λ
ISO/ASTM Guide 52701.) See Refs (2-16) for examples of the
3.1.10 specific net absorbance (Δk)—net absorbance, ΔA ,
types and magnitudes of the effects. It is recommended to
λ
at a selected wavelength, λ, divided by the optical pathlength,
calibrate the dosimetry system under the conditions of use
d, through the dosimeter material as follows:
(in-situ calibration) in order to help to account for the influence
quantities and reduce their associated uncertainty along with
Δk 5 ΔA ⁄d (2)
λ
batch to batch variations. Examples of such factors are
3.2 Definitions of other terms used in this practice that
temperature, humidity, dose rate and dose fractionation.
pertain to radiation measurement and dosimetry may be found
NOTE 1—Due to the variety of radiochromic dosimeter types the
in ISO/ASTM Practice 52628. Other terms that pertain to
manufacturer should be consulted for specific recommendations regarding
influence quantities and their significance for dosimeter use, shipment and
radiation measurement and dosimetry may be found in ASTM
storage.
Terminology E3083 and ISO Terminology 12749-4. Where
6.2 Pre-Irradiation Conditions:
appropriate, definitions used in these standards have been
derived from, and are consistent with definitions in ICRU 6.2.1 Dosimeter Conditioning and Packaging—Dosimeters
may be conditioned by the manufacturer to optimize water
Report 85a; and general metrological definitions given in the
VIM. content in the film, and then sealed in vapor and light tight
pouches to maintain that condition.
6.2.2 Time since Manufacture—The shelf-life of the differ-
ent types of radiochromic film dosimeters varies and the
Document produced by Working Group 2 of the Joint Committee for Guides in
manufacturer should be contacted for recommended duration.
Metrology (JCGM/WG 2). Available free of charge at the BIPM website (http://
www.bipm.org). However, it is recommended that users carry out performance
51275 − 21
NOTE 5—Light used for measurement of dosimeter response might
verification of pre-irradiation absorbance and post-irradiation
contain a UV component that can affect dosimeter response.
response stability over the useful life of the dosimeter batch.
6.2.3 Temperature—Exposure to extreme temperature dur-
7. Dosimetry system and its verification
ing shipment and storage at the user’s facility might affect
dosimeter response.
7.1 Components of the Radiochromic Film Dosimetry
6.2.4 Relative Humidity—Dosimeters may be packaged so
System—The following are components of radiochromic film
they are not affected by environmental changes in humidity;
dosimetry systems:
dosimeters without protective packaging might be affected.
7.1.1 Radiochromic Film Dosimeters—The film may be
6.2.5 Exposure to Light—Dosimeters may be packaged so
provided in bulk or in pouches of one or more dosimeters. A
they are not affected by exposure to light; dosimeters without
pouch provides humidity and light protection.
protective packaging might be affected.
7.1.2 Measurement Instruments—For each instrument used
to measure dosimeter response, determine and establish the
6.3 Conditions During Irradiation:
specific measurement settings capable of providing highly
6.3.1 Irradiation Temperature—Irradiation temperature is
reproducible results over the required dose range. For example,
expected to influence dosimeter response.
use the peak absorbance wavelength for a specific dosimeter to
6.3.2 Absorbed-dose Rate—Absorbed-dose rate might influ-
optimize measurement reproducibility. Some dosimeters may
ence dosimeter response.
require use of an off-peak wavelength to extend the usable dose
6.3.3 Dose Fractionation—Dose fractionation might influ-
range. Examples of appropriate analysis wavelengths for spe-
ence dosimeter response.
cific dosimetry systems are provided by the manufacturer and
6.3.4 Relative Humidity—For some dosimeters, the amount
in Refs (3-10, 18-21). Depending on the specific dosimetry
of water in the dosimeter is known to influence its response.
system, the response may be absorbance, change in
For dosimeters used outside manufacturer’s sealed packaging,
absorbance, specific absorbance or specific net absorbance.
it is recommended to calibrate the dosimetry system under the
7.1.2.1 Calibrated Spectrophotometer (or an equivalent
conditions of use (in-plant calibration) in order to mitigate any
instrument), capable of measuring optical absorbance at the
possible effect of variations in the amount of water in the
analysis wavelength and having documentation specifying
dosimeter and hence its response.
analysis wavelength range, accuracy of wavelength selection
6.3.5 Exposure to Light—Dosimeters may be packaged so
and absorbance determination, spectral bandwidth, and stray
they are not affected by exposure to light; dosimeters without
light rejection.
protective packaging might be affected.
6.3.6 Radiation Energy—The response of dosimeters has
NOTE 6—The selected spectrophotometer should be capable of satisfy-
been demonstrated to be independent of energy. However,
ing specified precision and dose range requirements. For example, in thin
when electron energy is low enough to result in a dose gradient
film dosimetry, the spectral bandwidth setting should be appropriate (for
example, several nm) for a given dosimeter thickness in order to avoid
through the thickness of the dosimeter, difficulties in interpre-
introducing optical interference fringes that adversely affect measurement
tation of the measured response may result (17).
reproducibility and can severely limit the lower end of achievable dose
range.
NOTE 2—At low energies the thickness of the packaging material might
give rise to measurement errors.
7.1.2.2 Densitometer, with appropriate traceable calibration
6.4 Post-Irradiation Conditions:
standards.
6.4.1 Time—Dosimeters may take significant time for the
7.1.2.3 Film Image Scanner, with appropriate traceable
absorbance to stabilize after irradiation (10-12, 18, 19). A post
calibration standards.
irradiation heat-treatment process may stabilize the absorbance
7.1.3 Dosimeter Holder, to position the dosimeter reproduc-
sooner.
ibly during the absorbance measurement process.
NOTE 3—The response of some film dosimeters can be stabilized by a 7.1.4 Calibrated Thickness Gauge (Optional), with appro-
post-irradiation heat treatment. Users should consult the manufacturer for
priate calibration standards.
specific recommendations but generally the packaging status and a
temperature and timer interval are specified as part of a heat treatment NOTE 7—Most users will elect not to implement an on-site thickness
procedure (for example, 55–65 °C for 15–30 min). measurement capability due to the technical difficulty associated with
NOTE 4—It is the responsibility of the user to establish a post-irradiation performing highly reproducible thickness measurements on soft surfaced
treatment process, and to ensure that the same procedure is followed film dosimeters. Instead, most users will either ignore thickness (treating
during calibration and during measurement. it as a constant) or utilize the average thickness as stated by the
manufacturer.
6.4.2 Temperature—Storage temperature after irradiation
7.2 Measurement Management System, including verifica-
might influence dosimeter response.
tion of the dosimetry system calibration curve resulting from
6.4.3 Relative Humidity—Water content in dosimeter after
calibration according to ISO/ASTM Practice 51261, and the
irradiation might influence dosimeter response.
procedures for its use.
6.4.4 Exposure to Light—Dosimeters may be packaged so
they are not affected by exposure to light; dosimeters without
7.3 Performance Verification of Instrumentation:
protective packaging might be affected.
7.3.1 At user-defined intervals b
...

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.
Designation: ISO/ASTM 51275 − 2013(E) 51275 − 21
Standard Practice for
Use of a Radiochromic Film Dosimetry System
This standard is issued under the fixed designation ISO/ASTM 51275; the number immediately following the designation indicates the
year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last
reapproval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This is a practice for using radiochromic film dosimetry systems to measure absorbed dose in materials irradiated by photons
or electrons in terms of absorbed dose to water. Radiochromic film dosimetry systems are generally used as routine dosimetry
systems.
1.2 The radiochromic film dosimeter is classified as a Typetype II dosimeter on the basis of the complex effect of influence
quantities. See ASTM Practice quantities (see ISO/ASTM E262852628.).
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 radiochromic film dosimetry system. It is intended to be read in conjunction with
ASTMISO/ASTM E262852628.
1.4 This practice covers the use of radiochromic film dosimetry systems under the following conditions:
1.4.1 The absorbed dose range is 1 Gy to 150 kGy.
-2 13 -1 2
1.4.2 The absorbed dose rate is 1 × 10 to 1 × 10 Gy·s (1-4).
1.4.3 The photon energy range is 0.1 to 50 MeV.
1.4.4 The electron energy range is 70 keV to 50 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 and healthsafety, 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.
This guidepractice 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 . Originally developed as a joint ASTM/ISO standard in conjunction with ISO/TC 85/WG 3.
Current edition approved April 9, 2013Oct. 1, 2021. Published June 2013May 2024. Originally published as ASTM E 1275–88. Last previous ASTM edition
ε1
E 1275–98approved in 1988. Last previous edition approved . ASTM E 1275–93 was adopted by ISO in 1998 with the intermediate designation ISO 15557:1998(E). The
present International Standard ISO/ASTM 51275:2013(E) replaces ISO 15557 and is a major revision of the last previous edition ISO/ASTM 51275:2004(E). in 2013 as
ISO/ASTM 51275:2013(E). DOI: 10.1520/51275-21.
The boldface numbers in parentheses refer to the bibliography at the end of this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
51275 − 21
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 Practice for Calibration of Routine Dosimetry Systems for Radiation Processing
51707 Guide for Estimating Uncertainties 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
2.3 International Commission on Radiation Units and Measurements (ICRU) Reports:
ICRU Report 85a Fundamental Quantities and Units for Ionizing Radiation
ICRU Report 80 Dosimetry Systems for Use in Radiation Processing
2.4 ISO/ASTM Standards:
12749-4 Nuclear energy – Vocabulary – Part 4: Dosimetry for radiation processing
2.5 Joint Committee for Guides in Metrology (JCGM) Reports:
JCGM 100:2008, GUM 1995, with minor corrections, Evaluation of measurement data – Guide to the Expression of Uncertainty
in Measurement
JCGM 200:2008, VIM, International vocabulary of metrology – Basis and general concepts 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’.
3.1.2 dosimeter—device having a reproducible, measurable response to radiation that can be used to measure the absorbed dose
in a given system.
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 dosimetrydosimeter response—reproducible, quantifiable effect produced in the dosimeter by ionizing radiation.
3.1.2.1 Discussion—
For radiochromic film dosimeters, the absorbance, specific absorbance or specific net absorbance is the dosimeter response.
3.1.3 dosimetrydosimeter stock—part of a dosimeter batch held by the user.
3.1.4 measurement management system—a set of interrelated or interacting elements necessary to achieve metrological
confirmation and continual control of measurement processes.
3.1.5 radiochromic film dosimeter—specially prepared film containing ingredients that undergo change in optical absorbance
under ionizing radiation, which can be related to absorbed dose to water.
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.
Available from the International Commission on Radiation Units and Measurements, 7910 Woodmont Ave., suite 800, Bethesda, MD 20814, USA.
Available from International Organization for Standardization (ISO), ISO Central Secretariat, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva, Switzerland,
https://www.iso.org.
Document produced by Working Group 1 of the Joint Committee for Guides in Metrology (JCGM/WG 1). 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/WG 2). Available free of charge at the BIPM website
(http://www.bipm.org).
51275 − 21
3.1.6 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.
3.1.7 response—see dosimeter response.
3.1.8 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.
3.1.9 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
k 5 A ⁄d (1)
λ
3.1.10 specific net absorbance (Δk)—(Δk)—net absorbance, ΔA , at a selected wavelength, λ, divided by the optical pathlength,
λ
d, through the dosimeter material as follows:
Δk 5 ΔA ⁄D (2)
λ
Δk 5 ΔA ⁄d (2)
λ
3.2 Definitions of other terms used in this practice 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 12749-4. Where appropriate, definitions used in E170 are compatible with these
standards have been derived from, and are consistent with definitions in ICRU Report 85a; that document, therefore, may be used
as an alternative reference.and general metrological definitions given in the VIM.
4. Significance and use
4.1 The radiochromic film dosimetry system provides a means for measuring absorbed dose based on radiation-induced change
in color using spectrophotometers, densitometers or scanned images.
4.2 Radiochromic film 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 Radiochromic film dosimeters are manufactured by various methods to produce freestanding or coated films, which are
flexible and transparent. They are generally supplied as small squares, strips, or long rolls or sheets that can be cut into a convenient
size for dosimetry purposes. The response of the dosimeters may be influenced by water content, irradiation temperature,
post-irradiation time to measurement, and other potential influence quantities that need to be taken into account. Many
commercially available dosimeters are supplied in light- and vapor-tight packages, which effectively protect against light and
changes in ambient humidity. The dosimeters should be calibrated under irradiation conditions that are similar to those in which
they will be used.
5.2 Ionizing radiation induces chemical reactions in the material, which create or enhance absorption bands in the visible or
ultraviolet regions, or both, of the optical spectrum. Absorbance determined at appropriate wavelengths within these
radiation-induced absorption bands is quantitatively related to the absorbed dose. ICRU Report 80 provides technical information
and historical development of the radiochromic film dosimetry systems in current use.
5.3 The radiation-induced change in absorbance of the radiochromic film depends on the wavelength of the light which is used
to make the measurement.
6. Influence quantities
6.1 Factors other than absorbed dose which influence the dosimeter response are referred to as influence quantities. Examples of
such factors are temperature and dose rate. See ASTM (See ISO/ASTM Guide E270152701.) See Refs (2-1416) for examples of
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the types and magnitudes of the effects. It is recommended to calibrate the dosimetry system under the conditions of use (in-situ
calibration) in order to help to account for the influence quantities and reduce their associated uncertainty along with batch to batch
variations. Examples of such factors are temperature, humidity, dose rate and dose fractionation.
NOTE 1—Due to the variety of radiochromic dosimeter types the manufacturer should be consulted for specific recommendations regarding influence
quantities and their significance for dosimeter use, shipment and storage.
6.2 Pre-Irradiation Conditions:
6.2.1 Dosimeter Conditioning and Packaging—Dosimeters may be conditioned by the manufacturer to optimize water content in
the film, and then sealed in vapor and light tight pouches to maintain that condition.
6.2.2 Time since Manufacture—The shelf-life of some the different types of radiochromic film dosimeters has been shown to
exceed nine years. varies and the manufacturer should be contacted for recommended duration. However, it is recommended that
users carry out performance verification of pre-irradiation absorbance and post-irradiation response stability over the useful life of
the dosimeter batch.
6.2.3 Temperature—Exposure to extreme temperature during shipment and storage at the user’s facility might affect dosimeter
response. The manufacturer should be consulted for specific recommendations for dosimeter shipment and storage.
6.2.4 Relative Humidity—Dosimeters may be packaged so they are not affected by environmental changes in humidity; dosimeters
without protective packaging might be affected. The manufacturer should be consulted for specific recommendations for dosimeter
shipment and storage.
6.2.5 Exposure to Light—Dosimeters may be packaged so they are not affected by exposure to light; dosimeters without protective
packaging might be affected. The manufacturer should be consulted for specific recommendations for dosimeter shipment and
storage.
6.3 Conditions During Irradiation:
6.3.1 Irradiation Temperature—Irradiation temperature is expected to influence dosimeter response. It is recommended to
calibrate the dosimetry system under the conditions of use (in-plant calibration) in order to mitigate the effect of temperature on
dosimeter response.
6.3.2 Absorbed-dose Rate—Absorbed-dose rate might influence dosimeter response. It is recommended to calibrate the dosimetry
system under the conditions of use (in-plant calibration) in order to mitigate any possible effect of dose rate on dosimeter response.
6.3.3 Dose Fractionation—Dose fractionation might influence dosimeter response. It is recommended to calibrate the dosimetry
system under the conditions of use (in-plant calibration) in order to mitigate any possible effect of dose fractionation.
6.3.4 Relative Humidity—For some dosimeters, the amount of water in the dosimeter is known to influence its response. For
dosimeters used outside manufacturer’s sealed packaging, it is recommended to calibrate the dosimetry system under the
conditions of use (in-plant calibration) in order to mitigate any possible effect of variations in the amount of water in the dosimeter
and hence its response.
6.3.5 Exposure to Light—Dosimeters may be packaged so they are not affected by exposure to light; dosimeters without protective
packaging might be affected.
6.3.6 Radiation Energy—The response of dosimeters has been demonstrated to be independent of energy. However, when electron
energy is low enough to result in a dose gradient through the thickness of the dosimeter, difficulties in interpretation of the
measured response may result (1517).
NOTE 2—At low energies the thickness of the packaging material might give rise to measurement errors.
6.4 Post-Irradiation Conditions:
6.4.1 Time—Dosimeters may take significant time for the absorbance to stabilize after irradiation (10-12, 16 and 1718, 19). A post
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irradiation heat-treatment process may stabilize the absorbance sooner. Dosimeter manufacturer should be consulted for specific
recommendation for post-irradiation heat treatment.
NOTE 3—The response of FWT-60 and B3 some film dosimeters can be stabilized by a post-irradiation heat treatment. Users should consult the
manufacturer for specific recommendations but generally the packaging status and a temperature and timer interval are specified as part of a heat treatment
procedure (for example, 55–65 °C for 15–30 min).
NOTE 4—It is the responsibility of the user to establish a post-irradiation treatment process, and to ensure that the same procedure is followed during
calibration and during measurement.
6.4.2 Temperature—Storage temperature after irradiation might influence dosimeter response. Dosimeter manufacturer should be
consulted for specific recommendation for storage of irradiated dosimeters.
6.4.3 Relative Humidity—Water content in dosimeter after irradiation might influence dosimeter response. Dosimeter manufac-
turer should be consulted for specific recommendation for storage of irradiated dosimeters.
6.4.4 Exposure to Light—Dosimeters may be packaged so they are not affected by exposure to light; dosimeters without protective
packaging might be affected.
6.5 Response Measurement Conditions:
6.5.1 Requirements for post irradiation conditions apply to conditions of measurement.
NOTE 5—Light used for measurement of dosimeter response might contain a UV component that can affect dosimeter response.
7. Dosimetry system and its verification
7.1 Components of the Radiochromic Film Dosimetry System—The following are components of radiochromic film dosimetry
systems:
7.1.1 Radiochromic Film Dosimeters—The film may be provided in bulk or in pouches of one or more dosimeters. A pouch
provides humidity and light protection.
7.1.2 Measurement Instruments—For each instrument used to measure dosimeter response, determine and establish the specific
measurement settings capable of providing highly reproducible results over the required dose range. For example, use the peak
absorbance wavelength for a specific dosimeter to optimize measurement reproducibility. Some dosimeters may require use of an
off-peak wavelength to extend the usable dose range. Examples of appropriate analysis wavelengths for specific dosimetry systems
are provided by the manufacturer and in Refs (3-10, 16-18-21). Depending on the specific dosimetry system, the response may be
absorbance, change in absorbance, specific absorbance or specific net absorbance.
7.1.2.1 Calibrated Spectrophotometer (or an equivalent instrument), with appropriate traceable calibration standards.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.
NOTE 6—Select a spectrophotometer The selected spectrophotometer should be capable of satisfying specified precision and dose range requirements. For
example, in thin film dosimetry, the spectral bandwidth setting mustshould be appropriate (for example, several nm) for a given dosimeter thickness in
order to avoid introducing optical interference fringes that adversely affect measurement reproducibility and can severely limit the lower end of achievable
dose range.
7.1.2.2 Densitometer, with appropriate traceable calibration standards.
7.1.2.3 Film Image Scanner, with appropriate traceable calibration standards.
7.1.3 Dosimeter Holder, to position the dosimeter reproducibly during the absorbance measurement process.
7.1.4 Calibrated Thickness Gauge (Optional), with appropriate calibration standards.
NOTE 7—Most users will elect not to implement an on-site thickness measurement capability due to the technical difficulty associated with performing
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highly reproducible thickness measurements on soft surfaced film dosimeters. Instead, most users will either ignore thickness (treating it as a constant)
or utilize the average thickness as stated by the manufacturer.
7.2 Measurement Management System, including verification of the dosimetry system calibration curve resulting from calibration
according to ISO/ASTM Practice 51261, and the procedures for its use.
7.3 Performance Verification of Instrumentation:
7.3.1 At prescribed time intervals, or in the event of suspected performance issues during periods of use, check measurements
against their calibration standards.user-defined intervals based on risk-assessment, the performance of the spectrophotometer shall
be verified, the result(s) documented, and the result(s) compared with the instrument specifications (see ASTM Practice E275).
7.3.1.1 Verify the accuracy of optical absorbance measurement at or near the analysis wavelength (at a minimum) over the full
range of the absorbance scale utilized for measurement of the dosimeter, for example t
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