ASTM ISO/ASTM51956-21

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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 51956 − 2013(E) 51956 − 21
Standard Practice for
Use of a Thermoluminescence-Dosimetry System (TLD
System) for Radiation Processing
This standard is issued under the fixed designation ISO/ASTM 51956; 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 practice covers procedures for the use of thermoluminescence dosimeters (TLDs) to measure the absorbed dose in
materials irradiated by photons or electrons in terms of absorbed dose to water. Thermoluminescence-dosimetry systems (TLD
systems) are generally used as routine dosimetry systems.
1.2 The thermoluminescence dosimeter (TLD) is classified as a type II dosimeter on the basis of the complex effect of influence
quantities on the dosimeter response. 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 TLD system. It is intended to be read in conjunction with ISO/ASTM 52628.
1.4 This practice covers the use of TLD systems under the following conditions:
1.4.1 The absorbed-dose range is from 1 Gy to 10 kGy.
-2 10 -1
1.4.2 The absorbed-dose rate is between 1 × 10 and 1 × 10 Gy s .
1.4.3 The radiation-energy range for photons and electrons is from 0.1 to 50 MeV.
1.5 This practice does not cover measurements of absorbed dose in materials subjected to neutron irradiation.
1.6 This practice does not cover procedures for the use of TLDs for determining absorbed dose in radiation-hardness testing of
electronic devices. devices or for clinical dosimetry. Procedures for the use of TLDs for radiation-hardness testing are given in
ASTM Practice E668. Procedures for use of TLDs in clinical dosimetry are given in ISO 28057.
1.7 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.
1.8 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 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 . Originally developed as a joint ASTM/ISO standard in conjunction with ISO/TC 85/WG 3.
Current edition approved Aug. 1, 2013Oct. 1, 2021. Published November 2013May 2024. Originally published as ASTM E 1956–98. The present International Standard
ISO/ASTM 51956:2013(E) is a major revision of the last previous edition ISO/ASTM 51956:2005(E).approved in 1998. Last previous edition approved in 2013 as ISO/ASTM
51956:2013(E). DOI: 10.1520/51956-21.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
51956 − 21
2. Referenced documents
2.1 ASTM Standards:
E170 Terminology Relating to Radiation Measurements and Dosimetry
E666 Practice for Calculating Absorbed Dose From Gamma or X Radiation
E668 Practice for Application of Thermoluminescence-Dosimetry (TLD) Systems for Determining Absorbed Dose in
Radiation-Hardness Testing of Electronic Devices
E3083 Terminology Relating to Radiation Processing: Dosimetry and Applications
2.2 ISO/ASTM Standards:
51261 Practice for Calibration of Routine Dosimetry Systems for Radiation Processing
51608 Practice for Dosimetry in an X-Ray (Bremsstrahlung) Facility for Radiation Processing
51649 Practice for Dosimetry in an Electron-Beam Facility for Radiation Processing at Energies Between 300 keV and 25 MeV
51702 Practice for Dosimetry in Gamma Irradiation Facilities for Radiation Processing
51707 Guide for Estimating Uncertainties in Dosimetry for Radiation Processing
51939 Practice for Blood Irradiation Dosimetry
51940 Guide for Dosimetry for Sterile Insect Release Programs
52628 Practice for Dosimetry in Radiation Processing
52701 Guide for Performance Characterization of Dosimeters and Dosimetry Systems for Use in Radiation Processing
2.3 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
2.4 ISO Standard:Standards:
ISO 10012 Measurement Management Systems—Requirements for Measurement Processes and Measuring Equipment
ISO 12749-4 Nuclear energy—Vocabulary—Part 4: Dosimetry for radiation processing
ISO 28057 Clinical dosimetry – Dosimetry with solid thermoluminescence detectors for photon and electron radiations in
radiotherapy
2.5 International Commission on Radiation Units and Measurements (ICRU) Report:
ICRU Report 80 Dosimetry Systems for Use in Radiation Processing
ICRU Report 85a Fundamental Quantities and Units for Ionizing Radiation
3. Terminology
3.1 Definitions:
3.1.1 annealing—thermal treatment of a TLD prior to irradiation or prior to readout.
3.1.1.1 Discussion—
Pre-irradiation annealing of TLDs is usually done to erase the effects of previous irradiation and to readjust the sensitivity of the
phosphor; pre-readout annealing usually is done to reduce low-temperature TLD response.
3.1.2 calibration—set of operations that establish, under specified conditions, the relationship between values of quantities
indicated by a measuring instrument or measuring system, or values represented by a material measure or a reference material, and
the corresponding values realized by standards.
3.1.2.1 Discussion—
Calibration conditions include environmental and irradiation conditions present during irradiation, storage and measurement of the
dosimeters that are used for the generation of a calibration curve. To achieve stable environmental conditions, it may be necessary
to condition the dosimeters before performing the calibration procedure.
3.1.3 calibration curve—expression of the relation between indication and corresponding measured quantity value. (VIM)
For referenced ASTM and ISO/ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book
of ASTM Standards volume information, refer to the standard’s Document Summary page on the ASTM website.
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.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.International Organization for
Standardization (ISO), ISO Central Secretariat, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva, Switzerland, https://www.iso.org.
Available from International Commission on Radiation Units and Measurements, 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814, USA.
51956 − 21
3.1.4 charged-particle equilibrium—condition in which the kinetic energy of charged particles (or electrons), excluding rest mass,
entering an infinitesimal volume of the irradiated material equals the kinetic energy of charge particles (or electrons) emerging
from it.
3.1.4.1 Discussion—
When electrons are the predominant charged particles, the term “electron equilibrium” is often used to describe charged-particle
equilibrium.
3.1.2 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.
3.1.3 dosimeter stock—part of a dosimeter batch held by the user.
3.1.7 dosimetry system—system used for measuring absorbed dose, consisting of dosimeters, measurement instruments and their
associated reference standards, and procedures for the system’s use.
3.1.8 electron equilibrium—charged-particle equilibrium for electrons. See charged-particle equilibrium.
3.1.9 measurement management system—set of interrelated or interacting elements necessary to achieve metrological confirmation
and continual control of measurement processes. (ISO 10012)
3.1.10 quality assurance—all systematic actions necessary to provide adequate confidence that a calibration, measurement, or
process is performed to a predefined level of quality.
3.1.11 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.
3.1.4 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 thermoluminescence dosimeter (TLD)—TL phosphor, alone or incorporated in a material, used for determining the absorbed
dose to materials.
3.1.5.1 Discussion—
For example, the TL phosphor is sometimes incorporated in a TFE-fluorocarbon matrix.
3.1.6 thermoluminescence dosimeter reader (TLD reader)—instrument used to measure the light emitted from a TLD consisting
essentially of a heating element, a light-measuring device, and appropriate electronics.
3.1.7 thermoluminescence dosimeter response (TLD response)—light emitted by the TLD and read out during its heating cycle
consisting of one of the following: (a) the total light output over the entire heating cycle, (b) a part of that total light output, or
(c) the peak amplitude of the light output.
3.1.8 thermoluminescence phosphor (TL phosphor)—material that stores, upon irradiation, a fraction of its absorbed dose in
various excited energy states and when thermally stimulated, it emits this stored energy as ultraviolet, visible, and infrared lights.
3.1.9 TLD preparation—procedure of cleaning, annealing, and encapsulating the TL phosphor prior to irradiation.
3.2 Definitions of other terms used in this standard that pertain to radiation measurement and dosimetry may be found in ASTM
TerminologyISO/ASTM Practice E17052628. Definitions Other terms that pertain to radiation measurement and dosimetry may
be found in ASTM Terminology E170E3083 are compatible with ICRU Report 85a; that document, therefore, may be used as an
alternative reference.and ISO Terminology ISO 12749-4. Where appropriate, definitions used in these standards have been derived
from, and are consistent with definitions in ICRU Report 85a, and general metrological definitions given in the VIM.
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4. Significance and use
4.1 In radiation processing, TLDs are mainly used in the irradiation of blood products (see ISO/ASTM Practice 51939) and insects
for sterile insect release programs (see ISO/ASTM Guide 51940). TLDs may also be used in other radiation processing applications
such as the sterilization of medical products, food irradiation, modification of polymers, irradiation of electronic devices, and
curing of inks, coatings and adhesives. (See ISO/ASTM Practices 51608, 51649, and 51702.)
4.2 For radiation processing, the absorbed-dose range of interest is from 1 Gy to 100 kGy. Some TLDs can be used in applications
requiring much lower absorbed doses (for example, for personnel dosimetry), but such applications are outside the scope of this
practice. Examples of TLDs and applicable dose ranges are given in Table 1. Information on various types of TLDs and their
applications can be found in Refs (1-10).
4.3 Information on other dosimetry systems used for radiation processing can be found in ICRU Report 80.
5. Overview
5.1 During the irradiation of certain crystalline materials, for example, LiF, CaF , CaSO , Li B O , and Al O , the filling of
2 4 2 4 7 2 3
electron and hole traps between the ground state and the conduction band results in stored energy that can be released as
luminescence during subsequent heating. TLD systems provide a means of determining absorbed dose to materials by measuring
this luminescence by the controlled heating of the irradiated crystalline material. The amount of luminescence emitted by the TL
phosphor upon heating can be directly related to absorbed dose by a calibration.
5.2 TLDs can be reused by subjecting the irradiated TLDs to an annealing process at a higher temperature to release all the
electron and hole traps.
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. Examples of such factors are temperature, relative humidity, light and dose rate (see
ISO/ASTM Guide 52701). See Refs (1-10) for examples of the types and magnitudes of the effects for different TLDs.
6.2 Pre-Irradiation Conditions:
6.2.1 Dosimeter Packaging—The TLD response is not usually influenced by the water content, so the TLDs are not usually
supplied in vapor tight pouches. They may be supplied in light tight pouches to minimize the effect of light.
A
TABLE 1 Types of TLDs and applicable dose ranges
Linear Dose Supralinear Dose
Type of TLD
Range, Gy Range, Gy
−5 3
LiF: Mg, Ti 10 − 1 1 − 10
−6
LiF:Mg, Cu, P 10 − 10 NA
−5 3
CaF : Mn 10 − 10 10 − 10
−5 2
CaF :Dy 10 − 6 6 − 5 × 10
−5 4
CaF :Tm 10 − 1 1 − 10
−6
Al O :C 10 − 1 1 − 30
2 3
−3 4
Al O :Mg, Y 10 − 10 NA
2 3
−4 2
BeO 10 − 1 1 − 10
−4 4
MgO 10 − 10 NA
−5 3
CaSO : Dy and CaSO :Tm 10 − 10 10 − 5 × 10
4 4
−4 2 2 4
Li B O : Mn 10 − 10 10 − 10
2 4 7
−5 3
Li B O : Cu 10 − 10 NA
2 4 7
−5 3
MgB O :Dy and MgB O :Tm 10 −50 50 − 5 × 10
4 7 4 7
A
This table is taken from Ref (6). Ranges are approximate, and may vary with
batch. Supralinearity refers to a region where the slope of the response versus
dose curve is greater than that for the linear region.
The boldface numbers in parentheses refer to the bibliography at the end of this standard.
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6.2.2 Time Since Manufacture—There is no known influence of time since manufacture on TLDs when stored under recommended
conditions. However, it is recommended that users carry out periodic performance verification of response over the time the
dosimeter batch is used.
6.2.3 Temperature—Exposure to extreme temperature during shipment and storage at the user’s facility might affect the TLD
response. Manufacturer should be consulted for specific recommendation for dosimeter shipment and storage.
6.2.4 Relative Humidity—The TLD response is not usually affected by environmental changes in humidity.
6.2.5 Exposure to Light—TLDs with high sensitivity should be packaged to protect them from light such as sunlight or fluorescent
light which have an appreciable ultraviolet component. Prolonged exposure to ultraviolet light before irradiation can cause spurious
TLD response or enhanced post-irradiation fading. Incandescent lighting should be used for the TLD preparation and readout areas.
However, brief exposures of a few minutes to normal room fluorescent lighting is not likely to significantly affect the TLD response
except for low dose measurements (<1 Gy) or measurements with high-sensitivity TLDs. TLDs, especially those with high
sensitivity, should be protected from light having an appreciable ultraviolet component.
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 TLD
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 the TLD response. It is recommended to calibrate the TLD 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 most types of TLDs, the amount of water in the dosimeter does not influence the response.
6.3.5 Exposure to Light—TLDs with high sensitivity should be protected from light such as sunlight or fluorescent light which
have an appreciable ultraviolet component. Prolonged exposure to ultraviolet light during irradiation can cause spurious TLD
response or enhanced post-irradiation fading.
6.3.6 Radiation Energy—Since the atomic number of many TLDs is higher than the atomic number for water, the absorbed dose
to water must be calculated from knowledge of the irradiation field and the composition of the dosimeter material (see ASTM
Practice E666).
6.4 Post-Irradiation Conditions:
6.4.1 Time—Some TLDs may take significant time for the electron and hole traps to stabilize after irradiation. Such dosimeters
may require an extended post irradiation time period (for example, 24 h) to stabilize sufficiently for measurement purposes.
6.4.2 Temperature—Temperature after irradiation might influence the TLD response. Dosimeter manufacturer should be consulted
for specific recommendation for storage of irradiated dosimeters.
6.4.3 Relative Humidity—The TLD response is not usually affected by the water content.
6.4.4 Exposure to Light—Dosimeters are sensitive to UV light, including the UV component in sunlight and facility lighting.
Dosimeters should be protected against light exposure.
6.5 Response Measurement Conditions:
6.5.1 Requirements for post irradiation conditions apply to conditions of measurement.
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7. Dosimetry system and its verification
7.1 Components of the Thermoluminescence Dosimetry (TLD) System—The following are components of TLD systems:
7.1.1 Thermoluminescence Dosimeters (TLDs)—TLDs are available from commercial suppliers in different forms such as loose
powder, chips or crystals encapsulated in glass or plastic.
7.1.2 Instrumentation—The thermoluminescence dosimeter (TLD) reader is a special instrument used to measure TLDs. It consists
of a heating element that subjects the TLD to a carefully controlled heating program that allows the freed electrons and holes from
traps to recombine with the emission of characteristic light. The emission of light as a function of temperature produces a glow
curve that is measured by the TLD reader and related to the absorbed dose.
7.1.3 Procedures for Its Use.
7.2 Measurement Management System specifying details of the preparation and handling of the TLDs and the verification,
calibration and quality assurance requirements for the TLD system shall be in place.
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, measurement instruments
should be checked against their calibration standards.
7.3.2 Implementation of a daily check program intended to verify instrument performance before and after measurement sessions
is also recommended.
8. Incoming dosimeter stock assessment
8.1 A protocol shall be established for the purchase, receipt, acceptance and storage of dosimeters.
8.2 The user shall perform an incoming inspection and acceptance testing for each shipment of dosimeters received. Samples
should be selected from all or as many incoming boxes as is possible.
8.2.1 Verify and document details such as batch ID, quantity, date received, miscellaneous descriptions (such as average mass) and
status of any shipping controls (such as temperature device’s indication of whether temperature limits may have been exceeded
during shipping).
8.2.2 Perform random sampling per documented procedures to verify dosimeter integrity.
8.2.3 It is also recommended that the user conduct dosimeter response testing at or near the planned high, medium and low doses
either to determine that the batch samples respond within expectation or to verify the batch response of a new dosimeter stock
against the results obtained with samples from a prior stock.
8.3 Retain sufficient dosimeters for additional investigations, for use during verification or for recalibration.
8.4 Store dosimeters according to the manufacturer’s recommendations, or specific user determined practices.
9. Calibration
9.1 Prior to initial use of each batch of dosimeters, the dosimetry system shall be calibrated in accordance with ISO/ASTM
Practice 51261 and the user’s procedures, which should specify details of the calibration and quality assurance requirements.
9.2 The user’s dosimetry system calibration shall take into account the influence quantities associated with pre-irradiation,
irradiation, and post-irradiation conditions applicable to the process in the user’s facility (see Section 6).
NOTE 1—Successful calibration of a TLD system requires use of calibration conditions that approximate those expected to be encountered during use.
If large seasonal temperature differences are anticipated, then the calibration should be conducted during periods that may better reflect
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