ISO/ASTM 51940:2022

Guidance for dosimetry for sterile insects release programs

1.1 This document outlines dosimetric procedures to be followed for the radiation-induced reproductive sterilization of live insects for use in pest management programs. The primary use of such insects is in the Sterile Insect Technique, where large numbers of reproductively sterile insects are released into the field to mate with and thus control pest populations of the same species. A secondary use of sterile insects is as benign hosts for rearing insect parasitoids. A third use is for testing detection traps for fruit flies and moths, and testing mating disruption products for moths. The procedures outlined in this document will help ensure that insects processed with ionizing radiation from gamma, electron, or X-ray sources receive absorbed doses within a predetermined range. Information on effective dose ranges for specific applications of insect sterilization, or on methodology for determining effective dose ranges, is not within the scope of this document. NOTE 1—Dosimetry is only one component of a total quality assurance program to ensure that irradiated insects are adequately sterilized and fully competitive or otherwise suitable for their intended purpose. 1.2 This document provides information on dosimetry for the irradiation of insects for these types of irradiators: selfcontained dry-storage 137Cs or 60Co irradiators, self-contained low-energy X-ray irradiators (maximum processing energies from 150 keV to 300 keV), large-scale gamma irradiators, and electron accelerators (electron and X-ray modes). NOTE 2—Additional, detailed information on dosimetric procedures to be followed in installation qualification, operational qualification, performance qualification, and routine product processing can be found in ISO/ASTM Practices 51608 (X-ray [bremsstrahlung] facilities processing at energies over 300 keV), 51649 (electron beam facilities), 51702 (large-scale gamma facilities), and 52116 (self-contained dry-storage gamma facilities), and in Ref (1)2 (self-contained X-ray facilities). 1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard except for the non-SI units of minute (min) hour (h) and day (d). These non-SI units are accepted for use within the SI system. 1.4 This document is one of a set of standards that provides recommendations for properly implementing and utilizing radiation processing. It is intended to be read in conjunction with ISO/ASTM Practice 52628. 1.5 The absorbed dose for insect sterilization is typically within the range of 20 Gy to 600 Gy. 1.6 This document refers, throughout the text, specifically to reproductive sterilization of insects. It is equally applicable to radiation sterilization of invertebrates from other taxa (for example, Acarina, Gastropoda) and to irradiation of live insects or other invertebrates for other purposes (for example, inducing mutations), provided the absorbed dose is within the range specified in 1.5. 1.7 This document also covers the use of radiation-sensitive indicators for the visual and qualitative indication that the insects have been irradiated (see ISO/ASTM Guide 51539). 1.8 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. 1.9 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.

Lignes directrices de la dosimétrie pour des programmes de lâchers d’insectes stériles

General Information

• Status: Published
• Publication Date: 11-Aug-2022
• ICS: 07.080 - Biology. Botany. Zoology
• ICS: 17.240 - Radiation measurements
• Technical Committee: ISO/TC 85 - Nuclear energy, nuclear technologies, and radiological protection
• Drafting Committee: ISO/TC 85 - Nuclear energy, nuclear technologies, and radiological protection
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 04-Apr-2025
• Completion Date: 30-Oct-2025

Relations

• Revises: ISO/ASTM 51940:2013 - Guide for dosimetry for sterile insects release programs
• Effective Date: 26-Nov-2021

Overview

ISO/ASTM 51940:2022 - Guidance for dosimetry for sterile insects release programs - provides dosimetric procedures and best-practice guidance for radiation‑induced reproductive sterilization of live insects used in pest management programs (primarily the Sterile Insect Technique, SIT). The standard focuses on ensuring insects processed with ionizing radiation (gamma, electron, or X‑ray) receive absorbed doses within a predetermined range. It is guidance (not a dose‑effect specification) and complements other ISO/ASTM radiation‑processing practices.

Keywords: ISO/ASTM 51940:2022, dosimetry, sterile insect release programs, Sterile Insect Technique, radiation sterilization, absorbed dose, Gray (Gy).

Key Topics

• Scope of application
  • Covers reproductive sterilization of insects and other invertebrates when absorbed dose is within the specified range.
  • Typical absorbed‑dose range: 20 Gy to 600 Gy.
• Types of irradiators addressed
  • Self‑contained dry‑storage 137Cs or 60Co irradiators
  • Self‑contained low‑energy X‑ray irradiators (150–300 keV)
  • Large‑scale gamma irradiators
  • Electron accelerators (electron and X‑ray modes)
• Dosimetry systems and dosimeters
  • Reference and routine dosimetry systems for calibration and processing
  • Dosimeter batches and sets, calibration traceable to approved laboratories
• Dose mapping and dose uniformity
  • Absorbed‑dose mapping to generate spatial dose distributions
  • Dose uniformity ratio (max/min) considerations for product geometry and packaging
• Qualification and quality assurance
  • Installation qualification (IQ), operational qualification (OQ), performance qualification (PQ)
  • Routine product processing procedures and measurement uncertainty evaluation
• Visual/qualitative indicators
  • Use of radiation‑sensitive indicators for process verification (see ISO/ASTM Guide 51539)
• Units and traceability
  • Values stated in SI units; Gray (Gy) as absorbed‑dose unit
• Limitations
  • Does not specify effective sterilization dose ranges for particular species nor prescribe regulatory/safety requirements

Applications

Who uses ISO/ASTM 51940:2022

• SIT program managers and pest‑control practitioners implementing sterile insect releases
• Irradiation facility engineers and operators (gamma, electron, X‑ray)
• Dosimetrists and laboratory personnel performing calibration and absorbed‑dose mapping
• Quality assurance and regulatory professionals ensuring traceability and process qualification
• Researchers validating sterilization workflows or using irradiated insects as hosts, test specimens, or for mating disruption trials

Practical benefits

• Improves reproducibility of sterilization treatments
• Supports QA programs to verify insects receive target absorbed doses
• Enables traceable dosimetry and documented OQ/PQ for routine processing

Related Standards

• ISO/ASTM Practice 52628 (radiation processing recommendations)
• ISO/ASTM Practices 51608 (X‑ray >300 keV), 51649 (electron beam), 51702 (large‑scale gamma), 52116 (self‑contained gamma)
• ISO/ASTM Guide 51539 (radiation‑sensitive indicators)

Standards Content (Sample)

INTERNATIONAL ISO/ASTM
STANDARD 51940
Fourth edition
2022-08
Guidance for dosimetry for sterile
insects release programs
Lignes directrices de la dosimétrie pour des programmes de lâchers
d’insectes stériles
Reference number
© ISO/ASTM International 2022
© ISO/ASTM International 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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ISO copyright office ASTM International
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Published in Switzerland
ii
© ISO/ASTM International 2022 – All rights reserved

Contents Page
1 Scope. 1
2 Referenced documents. 2
3 Terminology. 2
4 Significance and use. 4
5 Types of facilities and modes of operation. 4
6 Radiation source characteristics. 5
7 Dosimetry systems. 6
8 Installation and operational qualification. 7
9 Performance qualification. 8
10 Routine product processing. 9
11 Measurement uncertainty. 10
12 Keywords. 10
Annex. 11
Table 1 Examples of reference-standard dosimetry systems. 6
Table 2 Examples of routine dosimetry systems. 7
Table A1.1 Recommended Procedures. 11
© ISO/ASTM International 2022 – All rights reserved iii

Foreword
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in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of
ISO documents should be noted. International Standards are drafted in accordance with the editorial rules of
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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participation from affected stakeholders. ASTM technical committees follow rigorous due process balloting
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This document was prepared by ASTM Committee E61 Radiation Processing and by Technical Committee
ISO/TC 85, nuclear energy, nuclear technologies and radiological protection.
Thisfourtheditioncancelsandreplacesthethirdedition(ISO/ASTM51940:2013),whichhasbeentechnically
revised.
iv © ISO/ASTM International 2022 – All rights reserved

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.
Standard Guidance for
Dosimetry for Sterile Insect Release Programs
This standard is issued under the fixed designation ISO/ASTM 51940; the number immediately following the designation indicates the
year of original adoption or, in the case of revision, the year of last revision.
INTRODUCTION
Thepurposeofthisdocumentistopresentinformationontheuseofionizingenergy(radiation)for
the radiation-induced reproductive sterilization of live insects for use in pest management programs.
This document is intended to serve as a recommendation to be followed when using irradiation
technology where approved by an appropriate regulatory authority. It is not to be construed as a
requirement for the use of irradiation nor as a required code of practice. While the use of irradiation
involves certain essential requirements to attain the objective of the treatment, some parameters can
be varied in optimizing the process.
mance qualification, and routine product processing can be found in
1. Scope
ISO/ASTM Practices 51608 (X-ray [bremsstrahlung] facilities processing
1.1 This document outlines dosimetric procedures to be
at energies over 300 keV), 51649 (electron beam facilities), 51702
followed for the radiation-induced reproductive sterilization of
(large-scale gamma facilities), and 52116 (self-contained dry-storage
gamma facilities), and in Ref (1) (self-contained X-ray facilities).
liveinsectsforuseinpestmanagementprograms.Theprimary
use of such insects is in the Sterile Insect Technique, where
1.3 The values stated in SI units are to be regarded as
largenumbersofreproductivelysterileinsectsarereleasedinto
standard. No other units of measurement are included in this
the field to mate with and thus control pest populations of the
standard except for the non-SI units of minute (min) hour (h)
same species. A secondary use of sterile insects is as benign
and day (d).These non-SI units are accepted for use within the
hosts for rearing insect parasitoids. A third use is for testing
SI system.
detection traps for fruit flies and moths, and testing mating
1.4 This document is one of a set of standards that provides
disruption products for moths. The procedures outlined in this
recommendations for properly implementing and utilizing
document will help ensure that insects processed with ionizing
radiation processing. It is intended to be read in conjunction
radiation from gamma, electron, or X-ray sources receive
with ISO/ASTM Practice 52628.
absorbed doses within a predetermined range. Information on
1.5 The absorbed dose for insect sterilization is typically
effective dose ranges for specific applications of insect
within the range of 20 Gy to 600 Gy.
sterilization, or on methodology for determining effective dose
ranges, is not within the scope of this document.
1.6 Thisdocumentrefers,throughoutthetext,specificallyto
NOTE 1—Dosimetry is only one component of a total quality assurance
reproductive sterilization of insects. It is equally applicable to
programtoensurethatirradiatedinsectsareadequatelysterilizedandfully
radiation sterilization of invertebrates from other taxa (for
competitive or otherwise suitable for their intended purpose.
example,Acarina,Gastropoda)andtoirradiationofliveinsects
1.2 This document provides information on dosimetry for
or other invertebrates for other purposes (for example, induc-
the irradiation of insects for these types of irradiators: self-
ing mutations), provided the absorbed dose is within the range
137 60
contained dry-storage Cs or Co irradiators, self-contained
specified in 1.5.
low-energy X-ray irradiators (maximum processing energies
1.7 Thisdocumentalsocoverstheuseofradiation-sensitive
from 150 keV to 300 keV), large-scale gamma irradiators, and
indicators for the visual and qualitative indication that the
electron accelerators (electron and X-ray modes).
insects have been irradiated (see ISO/ASTM Guide 51539).
NOTE 2—Additional, detailed information on dosimetric procedures to
be followed in installation qualification, operational qualification, perfor-
1.8 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
This document is under the jurisdiction of ASTM Committee E61 on Radiation
priate safety, health, and environmental practices and deter-
Processing and is the direct responsibility of Subcommittee E61.04 on Specialty
mine the applicability of regulatory limitations prior to use.
Application, and is also under the jurisdiction of ISO/TC 85/WG 3.
Current edition approved May 20, 2022. Published August 2022. Originally
published as ASTM E 1940–98. The present International Standard ISO/ASTM
51940:2022(E) replaces and is a major revision of the last previous edition Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
ISO/ASTM 51940:2013(E). this standard.
© ISO/ASTM International 2022 – All rights reserved
1.9 This international standard was developed in accor- ISO 12749-4Nuclear energy – Vocabulary – Part 4: Dosim-
dance with internationally recognized principles on standard- etry for radiation processing
ization established in the Decision on Principles for the
2.5 Joint Committee for Guides in Metrology (JCGM)
Development of International Standards, Guides and Recom-
Reports:
mendations issued by the World Trade Organization Technical
JCGM 100:2008, GUM 1995, with minor corrections,
Barriers to Trade (TBT) Committee.
Evaluation of measurement data – Guide to the Expres-
sion of Uncertainty in Measurement
2. Referenced documents
JCGM 200:2012, VIMInternational Vocabulary of Metrol-
3 7
2.1 ASTM Standards: ogy – Basic and General Concepts andAssociatedTerms
E3083Terminology Relating to Radiation Processing: Do-
3. Terminology
simetry and Applications
2.2 ISO/ASTM Standards: 3.1 Definitions:
51261Practice for Calibration of Routine Dosimetry Sys- 3.1.1 absorbed dose (D)—quotient of dε¯ by dm, where dε¯ is
tems for Radiation Processing the mean energy imparted by ionizing radiation to matter of
51275Practice for Use of a Radiochromic Film Dosimetry mass dm thus
System
D5 dε¯/dm
51310Practice for Use of a Radiochromic Optical Wave-
3.1.1.1 Discussion—TheSIunitofabsorbeddoseisthegray
guide Dosimetry System
(Gy),where1grayisequivalenttotheabsorptionof1jouleper
51539Guide for Use of Radiation-Sensitive Indicators
kilogram of the specified material (1 Gy=1J/ kg).
51607Practice for Use of an Alanine-EPR Dosimetry Sys-
3.1.2 absorbed-dose mapping—measurement of absorbed-
tem
dose within an irradiated product to produce a one-, two- or
51608PracticeforDosimetryinanX-Ray(Bremsstrahlung)
three-dimensionaldistributionofabsorbeddose,thusrendering
Facility for Radiation Processing at Energies Between 50
a map of absorbed-dose values.
keV and 7.5 MeV
˙
3.1.3 absorbed-dose rate, D—absorbed dose in a material
51649Practice for Dosimetry in an Electron Beam Facility
per incremental time interval, that is, the quotient of dD by dt.
for Radiation Processing at Energies Between 300 keV
−1
Also see ASTM Terminology E3083. The SI unit is Gy·s
and 25 MeV
51702Practice for Dosimetry in a Gamma Facility for
˙
D5 dD/dt
Radiation Processing
3.1.3.1 Discussion—The absorbed-dose rate can be speci-
51707Guide for Estimation of Measurement Uncertainty in
fied in terms of its average value over long-time intervals, for
Dosimetry for Radiation Processing −1 −1
example in units of Gy·min or Gy·h
51956PracticeforUseofaThermoluminescence-Dosimetry
3.1.4 approved laboratory—laboratory that is a recognized
System (TLD System) for Radiation Processing
nationalmetrologyinstitute,orhasbeenformallyaccreditedto
52116Practice for Dosimetry for a Self-Contained Dry-
ISO/IEC 17025, or has a quality system consistent with the
Storage Gamma-Ray Irradiator
requirements of ISO/IEC 17025.
52303Guide forAbsorbed-Dose Mapping in Radiation Pro-
3.1.4.1 Discussion—A recognized national metrology insti-
cessing Facilities
tute or other calibration laboratory accredited to ISO/IEC
52628Practice for Dosimetry in Radiation Processing
17025 should be used in order to ensure traceability to a
52701Guide for Performance Characterization of Dosim-
national or international standard. A calibration certificate
eters and Dosimetry Systems for Use in Radiation Pro-
provided by a laboratory not having formal recognition or
cessing
accreditation will not necessarily be proof of traceability to a
2.3 International Commission on Radiation Units and Mea-
national or international standard.
surements (ICRU) Reports:
3.1.5 calibration [VIM, 6.11]—set of operations that
ICRU Report 80Dosimetry Systems for Use in Radiation
establish, under specified conditions, the relationship between
Processing
values of quantities indicated by a measuring instrument or
ICRU 85aFundamental Units and Quantities for Ionizing
measuringsystem,orvaluesrepresentedbyamaterialmeasure
Radiation
5 or a reference material, and the corresponding values realized
2.4 ISO Standards:
by standards.
ISO/IEC 17025General Requirements for the Competence
3.1.5.1 Discussion—Calibrationconditionsincludeenviron-
of Testing and Calibration Laboratories
mental and irradiation conditions present during irradiation,
storageandmeasurementofthedosimetersthatareusedforthe
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 DocumentproducedbyWorkingGroup1oftheJointCommitteeforMetrology
Document Summary page on the ASTM website. (JCGM/WG 1). Available free of charge at the BIPM website (http://
Available from the International Commission on Radiation Units and www.bipm.org).
Measurements, 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814, USA. DocumentproducedbyWorkingGroup2oftheJointCommitteeforMetrology
Available from International Organization for Standardization (ISO), 1 Rue de (JCGM/WG 2). Available free of charge at the BIPM website (http://
Varembé, Case Postale 56, CH-1211, Geneva 20, Switzerland. www.bipm.org).
© ISO/ASTM International 2022 – All rights reserved
generation of a calibration curve. To achieve stable environ- or other durable material. When canisters are used, insects are
mental conditions, it may be necessary to condition the often held secondarily within the canister in a plastic bag or
dosimeters before performing the calibration procedure. other disposable container.
3.1.6 dose uniformity ratio—ratioofmaximumtominimum
3.1.15 irradiator turntable—device used to rotate the
absorbed dose within the irradiated product.
sample during the irradiation process so as to improve dose
3.1.6.1 Discussion—The concept is also referred to as the
uniformity.
max/min dose ratio or DUR.
3.1.15.1 Discussion—An irradiator turntable is often re-
ferred to as a turntable. Some irradiator geometries, for
3.1.7 dosimeter—device that, when irradiated, exhibits a
quantifiable change that can be related to a dosimetric quantity example, with an annular array of radiation sources surround-
ing the product, may not need a turntable.
using appropriate measurement instruments and procedures.
3.1.8 dosimeter batch—quantity of dosimeters made from a
3.1.16 operational qualification (OQ)—processofobtaining
specific mass of material with uniform composition, fabricated
and documenting evidence that installed equipment operates
in a single production run under controlled, consistent condi-
within predetermined limits when used in accordance with its
tions and having a unique identification code.
operational procedures.
3.1.9 dosimeter set—one or more dosimeters used to mea-
3.1.17 performance qualification (PQ)—process of obtain-
suretheabsorbeddoseatalocationandwhoseaveragereading
ing and documenting evidence that the equipment, as installed
is used to determine absorbed dose at that location.
and operated in accordance with operation procedures, consis-
tently performs in accordance with predetermined criteria and
3.1.10 dosimetry system—interrelated elements used for
thereby yields product meeting its specification.
measuring a dosimetric quantity, including dosimeters, instru-
ments and their associated reference standards, and procedures
3.1.18 radiation-sensitive indicator—material such as a
for their use.
coated or impregnated adhesive-backed substrate, ink, coating
3.1.11 influence quantity—quantity that, in a direct or other materials which may be affixed to or printed on the
measurement, does not affect the quantity that is actually product or irradiation container and which undergoes a visual
measured, but affects the relation between the indication and change when exposed to ionizing radiation (see ISO/ASTM
the measurement result. Guide 51539).
3.1.11.1 Discussion—(1) In dosimetry for radiation
3.1.18.1 Discussion—Radiation-sensitive indicators are of-
processing, typical examples of influence quantities include
ten referred to as “indicators.” Indicators may be used to show
radiation type and energy, irradiation temperature, dose rate
that products have been exposed to ionizing radiation. They
and the time interval between irradiation and determination of
can be used to provide a visual and qualitative indication of
the indication of the dosimeter. (2) The dosimeter’s response
radiation exposure and can be used to distinguish between
(e.g. color change) is measured and related to dose via the
irradiated and unirradiated samples. Indicators cannot be used
calibrationcurve.Thedosimeter’ssignalmaybesusceptibleto
as a substitute for proper dosimetry.
the influence quantity, and therefore the interpretation of dose,
3.1.19 reference standard dosimetry system—dosimetry
not the actual dose.
system, generally having the highest metrological quality
3.1.12 in-situ/in-plant calibration—calibration where the
available at a given location or in a given organization, from
dosimeter irradiation is performed in the place of use of the
which measurements made there are derived.
routine dosimeters.
3.1.20 routine dosimetry system—dosimetry system cali-
3.1.12.1 Discussion—In-situ/in-plant calibration of dosim-
brated against a reference standard dosimetry system and used
etry systems refers to irradiation of routine dosimeters along
for routine absorbed-dose measurements, including dose map-
with reference or transfer dosimeters, under operating condi-
ping and process monitoring.
tions that are representative of the routine processing
environment, for the purpose of developing a calibration curve
3.1.21 simulated product—mass of material with absorption
for the routine dosimetry systems. and scattering properties similar to those of the product,
material or substance to be irradiated.
3.1.13 installation qualification—process of obtaining and
3.1.21.1 Discussion—Simulatedproductisusedduringirra-
documenting evidence that equipment has been provided and
installed in accordance with its specification. diator characterization as a substitute for the actual product,
material, or substance to be irradiated. When used in routine
3.1.14 irradiation container—holder in which product is
production runs in order to compensate for the absence of
placed during the irradiation process.
product, it is sometimes referred to as compensating dummy.
3.1.14.1 Discussion—For insect irradiation, the configura-
When used for absorbed-dose mapping, simulated product is
tionofirradiationcontainersvarieswidelywithsuchfactorsas
sometimes referred to as a phantom material.
type and energy of radiation, irradiator design, insect species,
insect stage being irradiated, and other process specifications 3.1.22 traceability—propertyoftheresultofameasurement
(for example, some insects are irradiated in reduced-oxygen or the value of a standard whereby it can be related to stated
atmospheres, requiring air-tight containers). Irradiation con- references, usually national or international standards, through
tainers for insects range from single-use items such as paper an unbroken chain of comparisons all having stated uncertain-
cylinders or plastic bags to reusable canisters of stainless steel ties.
© ISO/ASTM International 2022 – All rights reserved
3.1.22.1 Discussion—Theunbrokenchainofcomparisonsis 4.2 Another use of factory-reared insects is in the produc-
called a “traceability chain.” tion of parasitoids for release against populations of insect
pests (4). Parasitoids are insects that spend the larval stage
3.1.23 transfer standard dosimetry system—dosimetry sys-
feeding within or on the body of a “host” species, typically
tem used as an intermediary to calibrate other dosimetry
killing the host. In some parasitoid programs, factory-reared
systems.
host insects are irradiated before being offered to parasitoids.
3.1.24 transit dose—absorbed dose delivered to a product
This eliminates the need to separate unparasitized hosts from
(or a dosimeter) while it travels between the non-irradiation
parasitoids so that fertile, unparasitized host insects are not
position and the irradiation position, or in the case of a
inadvertently released into the field.
movable source while the source moves into and out of its
4.3 An additional use of factory-reared insects is for testing
irradiation position.
detection traps for fruit flies and moths, and testing mating
3.1.25 type I dosimeter—dosimeter of high metrological
disruption products for moths.
quality, the response of which is affected by individual influ-
4.4 Factory-reared insects may be treated with ionizing
ence quantities in a way that is well-defined and capable of
137 60
radiation,suchasgammaradiationfrom Csor Cosources,
expression in terms of independent correction factors.
or X-radiation or electrons from accelerators. Gamma irradia-
3.1.26 type II dosimeter—dosimeter, the response of which
tion of insects is often carried out in small, fixed-geometry,
isaffectedbyinfluencequantitiesinacomplexwaythatcannot
dry-storage irradiators (5). Dosimetry methods for gamma and
practically be expressed in terms of independent correction
X-ray irradiation of insects have been demonstrated and
factors.
include useful procedures for measuring the absorbed dose
3.2 Definitions of Terms Specific to This Standard: distribution throughout the volume of the irradiation contain-
er(s)inthesesmallirradiators(ASTMPractice52116andRefs
3.2.1 factory-reared insects—insects that are raised in large
(1, 6)) as well as large-scale gamma irradiators (ISO/ASTM
quantities in a laboratory or factory setting for use, following
Practice 51702 and Ref (7)).
reproductivesterilizationthroughirradiation,asliveanimalsin
pest management programs.
4.5 Specifications for irradiation of factory-reared insects
include a lower limit of absorbed dose and may include a
3.3 Definitions of other terms used in this standard that
central target dose and an upper limit. These values are based
pertain to radiation measurement and dosimetry may be found
on program requirements and on scientific data on effects of
in ISO/ASTM Practice 52628. Other terms that pertain to
absorbeddoseonthesterility,viability,andcompetitivenessof
radiation measurement and dosimetry may be found inASTM
the factory-reared insects.
Terminology E3083 and ISO Terminology ISO 12749-4.
Where appropriate, definitions used in these standards have
4.6 To demonstrate control of the radiation process, the
beenderivedfrom,andareconsistentwithdefinitionsinICRU
absorbed dose must be measured using a calibrated dosimetry
Report 85a, and general metrological definitions given in the
system. Regulations or policies under which the facility oper-
VIM.
ates may require the calibration to be traceable to appropriate
national or international standards. The radiation-induced
4. Significance and use
change in the dosimeter is evaluated and related to absorbed
dose through calibration (ISO/ASTM Practice 51261).
4.1 The major use of factory-reared insects is in sterile
insectreleaseprograms(forexample,SterileInsectTechnique,
4.7 For each irradiator, absorbed-dose rate at a reference
or SIT) for suppressing or eradicating pest populations (2, 3).
position within the irradiated volume of insects or simulated
Large numbers of reproductively sterile (irradiated) insects are
product is measured using a transfer or reference standard
released into an area where a wild “target population” of the
dosimetry system. That measurement provides a basis for
same species exists, or sterile insects are released into an area
calculatingthedurationofirradiation,conveyorspeed,orother
as a preventative measure to protect against the wild pest
parameterrequiredtodeliverthespecifiedabsorbeddosetothe
establishing. The wild population is reduced to the extent that
insects.
the sterile males are successful in mating with wild females.
4.8 Absorbed-dose mapping for establishing magnitudes
The radiation dose absorbed by the factory-reared insects
and locations of minimum dose (D ) and maximum dose
min
should be within a range that induces the desired level of
(D ) is performed using actual product or simulated product
max
sterility without substantially reducing the ability of factory-
(5).
reared males to compete with wild males for mates. In some
cases, sterile females may also be released as part of an SIT
5. Types of facilities and modes of operation
program.SpeciestargetedbySITprogramsaretypicallymajor
pestsaffectingagricultureorhumanhealth,sotheassuranceby 5.1 Self-Contained Irradiators—Self-contained irradiators
standardized dosimetry that insects have been properly irradi- expose samples to gamma irradiation produced by isotopes of
137 60
ated is of crucial importance to agriculture growers, agricul- either Cs or Co (8, 9) (ISO/ASTM Practice 52116), or to
tural regulators, public health officials, and the public (3). The lowenergyX-radiation(bremsstrahlung)producedbyanX-ray
irradiator operator must demonstrate by means of accurate tube. These irradiators house their radiation source in a
absorbed-dose measurements that all insects have received protective lead shield or other appropriate high atomic number
absorbed dose within the specified range. material in accordance with the safety requirements. Currently
© ISO/ASTM International 2022 – All rights reserved
available units using low energy X-radiation (bremsstrahlung) 6.1.2 Cobalt-60 emits photons with energies of approxi-
require less shielding than units containing gamma-emitting mately 1.17 MeV and 1.33 MeV in nearly equal proportions.
radioactive isotopes. Such units containing radionuclides usu- Cesium-137 emits photons with energies of approximately
ally have a mechanism to move the canister from the load/ 0.662 MeV (11).
60 137
unload position to the irradiation position.
6.1.3 The radioactive decay half-lives for Co and Cs
5.1.1 Some common methods used for improving absorbed are regularly reviewed and updated. The most recent publica-
dose uniformity in the insect canister are to either rotate the
tionbytheNationalInstituteofStandardsandTechnology(12)
canister holding the insects in front of the radiation source or gave values of 1925.20 d (60.25 d) for Co and 11018.3 d
137 137
to have multiple sources irradiating the product from different
(69.5d)for Cs.Inaddition,the Csradiationsourcemay
directions. contain radioimpurities which should be quantified by the
source manufacturer.
5.2 Large-Scale Panoramic Gamma Irradiators (see ISO/
6.1.4 For gamma sources, the only variation in the source
ASTM Practice 51702)—Gamma irradiation of insects is also
output is the known reduction in the activity caused by
carried out in large-scale irradiators, either wet-storage or
radioactive decay. This reduction in the source output and the
dry-storage. In these facilities, the source typically consists of
required increase in the irradiation time to deliver the same
eitherasinglerodoraseriesofrods(pencils)thatcontain Co
dose may be calculated (see Eq 1 and Eq 2 or Eq 3 from 8.2.3)
and can be raised or lowered into a large irradiation room.
or obtained from tables provided by the irradiator manufac-
When retracted from the irradiation room, the source is
turer.
shielded by water (wet-storage; IAEA Category IV (10),or
lead or other appropriate high atomic number material (dry-
6.2 X-ray Irradiators:
storage; IAEA Category II (10), or both.
6.2.1 Low energy X-ray irradiators use X-ray tubes that
5.2.1 Continuous Operation—A common method of use is
consist of an electron source (generally a heated wire, a
for irradiation containers to be carried on a conveyor in one or
filament which emits electrons), an electrostatic field to accel-
more revolutions around a central source, resulting in a
erate these electrons, and a converter to generate X-radiation
relatively uniform absorbed dose. The source is retracted from
(13, 14).
the irradiation room only when the irradiator is not in use.
6.2.2 An X-ray (bremsstrahlung) irradiator emits short
5.2.2 Batch Operation—An alternative method of use is to
wavelength electromagnetic radiation, which is analogous to
place irradiation container(s) of insects into the irradiation
gamma radiation from radioactive sources. Although their
room while the source is shielded, and then raise or lower the
effectsonirradiatedmaterialsaregenerallysimilar,thesekinds
source into the irradiation room for the length of time required
of radiation differ in their energy spectra (see 6.2.3), angular
to achieve the desired absorbed dose. For this mode of
distribution, and dose rates. The physical characteristics of the
operation,eachirradiationcontaineristypicallyrotatedaround
X-radiation (bremsstrahlung) field depend on the design of the
its own axis to improve dose uniformity.
X-ray tube.
6.2.3 Currently available low-energy X-ray irradiators gen-
5.3 Electron Accelerator—Accelerator-generated high en-
erate X-radiation with a maximum energy of a few hundred
ergy (3-10 MeV) electrons can also be used for insect irradia-
keV. The spectrum of the X-ray energy extends from the
tion. Such irradiators are housed in heavily shielded rooms.
maximumenergytoapproximately30keV.Effectiveenergyor
5.3.1 Typically, accelerators produce a narrow electron
other energy spectrum characteristics are needed for character-
beamthatisscannedtocoverthelengthandwidthoftheinsect
ization of dosimeter response (see Ref 15).
container, generally a tray.
5.3.2 X-radiation (bremsstrahlung) produced by striking an
NOTE 3—With lower photon energy, some dosimetry systems that are
X-ray target with an electron beam can also be used for this
commonly used with gamma irradiators and accelerators are not appli-
purpose. The target is made of tungsten, tantalum, or other cable to low-energy X-ray irradiators (see Table 1 and Table 2, and Refs
(1, 13, 15, 16). For example, Farmer-type ionization chambers are
metal with a high atomic number, high melting temperature,
appropriateasreferencestandarddosimetrysystemsforlow-energyX-ray
and high thermal conductivity.
irradiators (1, 13, 17).
5.3.3 For processing, insects are typically carried on a
6.2.4 The energy of the X-radiation influences the size and
movingconveyorthroughtheelectronorX-raybeam.Because
shape of the canister needed to achieve the desired level of
of the narrow angular distribution of the radiation, use of
doseuniformityintheinsectcanister.Filtersareusedtoreduce
continuously moving conveyors (rather than static-irradiation
the low-energy components to improve dose uniformity in the
or shuffle-dwell systems) enhances dose uniformity.
canister. These filters may form part of the X-ray tube or may
5.3.4 Additional information on electron and X-ray facili-
be material added to the irradiator or canister. Reflectors may
ties and their modes of operation may be found in ISO/ASTM
also be used to improve the dose uniformity.
Practices 51649 (electrons) and 51608 (X-radiation).
6.2.5 The absorbed-dose rate and thus time of irradiation is
determined by the tube current.
6. Radiation source characteristics
6.1 Gamma Irradiators: 6.3 Electron Accelerator (Electron and X-ray Modes):
6.1.1 The source of gamma radiation used in the irradiators 6.3.1 For an electron accelerator, the two principal beam
137 60
considered in this practice consists of sealed Cs or Co characteristics are the energy spectrum and the average beam
radionuclides that are typically linear rods arranged in one or current. The electron energy spectrum affects the variation of
more planar or annular arrays. absorbed dose with depth in a given material, and the average
© ISO/ASTM International 2022 – All rights reserved
beam current affects the absorbed-dose rate. Because of low national standards laboratory or an approved laboratory. In the
penetration of electrons, electron energy of at least 3 MeV is case of transfer standard dosimetry systems, dosimeters are
necessary to achieve useful dose uniformity.
sent to a facility for irradiation and then returned to the issuing
6.3.1.1 Direct-actionelectronacceleratorsthatemploydcor
laboratory for measurement. The requirement that dosimeters
pulsed high-voltage generators typically produce electron en-
be transported without unduly increasing the measurement
ergies up to 5 MeV.
uncertainty restricts the type of dosimeter that can be used.
6.3.1.2 Indirect-action electron accelerators use microwave
Alanine/EPR,dichromateandCeric-Cerousdosimetrysystems
or very high frequency (VHF) ac power to produce electron
are commonly used in this way.
energies typically from 5 MeV to 15 MeV.
(3)The dosimeter used in a reference standard dosimetry
6.3.2 For an X-ray (bremsstrahlung) facility, besides beam
system is generally a type I dosimeter. The expanded uncer-
characteristics noted in 6.3.1, X-ray target design is a critical
tainty achievable with measurements made using a reference
parameter. X-radiation is similar to gamma radiation from
standard dosimetry system is typically of the order of63% (at
radioactive isotopic sources. Although their effects on materi-
the 95 % confidence level).
als are generally similar, these kinds of radiation differ in their
(4)Examples of reference standard dosimetry systems are
energy spectra, angular distributions, and absorbed-dose rates.
given in Table 1.
The continuous energy spectrum of the X-radiation
7.1.2.2 Routine Dosimetry Systems:
(bremsstrahlung)extendsfromapproximately35keVuptothe
(1)The classification of a dosimetry system as a routine
maximum energy of the electrons incident on the X-ray target
dosimetry system is based on its application, that is, routine
(see ISO/ASTM Practice 51608). In some X-ray facilities,
absorbed-dose measurements, including dose mapping and
spectrumfiltrationisusedtoreducethelowenergycomponent
process monitoring.
of the radiation, thus improving dose uniformity.
(2)The dosimeter used in a routine dosimetry system is
generally a type II dosimeter, although there may be
7. Dosimetry systems
exceptions, for example the use of type I alanine dosimeters.
7.1 Description of Dosimeters and Dosimetry Systems—
Theexpandeduncertaintyachievablewithmeasurementsmade
Classificationofdosimetersanddosimetrysystemsisbasedon
using a routine dosimetry system is typically of the order of
the inherent metrological dosimeter properties and the field of
6% (at the 95% confidence level).
application of the dosimetry system (see ISO/ASTM Practice
(3)Examples of routine dosimetry systems are listed in
52628). These classifications influence both the selection and
Table 2.
calibration of dosimetry systems.
7.1.1 Classification of Dosimeters—Classificationofdosim-
7.2 Routine Dosimetry System Calibration:
eters is based on their inherent metrological properties. The
7.2.1 Dosimetry systems consist of dosimeters, measure-
methodofmeasurementmaybeimportantintheclassification,
ment instruments and their associated reference standards, and
but the classification does not include consideration of the
proceduresforthesystem’suse.Priortouse,routinedosimetry
actual instrumentation used, or the quality of preparation
systems shall be calibrated in accordance with documented
(manufacturer) of the dosimeter. See ISO/ASTM Practice
procedures that specify details of the calibration process.
52628 for a list of type I and type II dosimeters.
Detailed calibration procedures are provided in ISO/ASTM
7.1.2 Classification of Dosimetry Systems:
51261. All dosimetry equipment requires either calibration
7.1.2.1 Reference Standard Dosimetry Systems:
traceable to appropriate standards or performance checks to
(1)The classification of a dosimetry system as a reference
verify its operation (for more information, see the specific
standard dosimetry system is based on its application. Refer-
ISO/ASTM standard for the dosimetry system being used).
ence standard dosimetry systems are used as standards to
Similarly, the dosimetry system shall be calibrated for each
calibrate other dosimetry systems that are used for routine
dosimeterbatchusedatthefacility.Ifrequiredbyregulationor
measurements. In addition, the reference standard dosimetry
policy, it is necessary to demonstrate that dose measurements
systemsareusedtocertifytheabsorbed-doserateatareference
are traceable to recognized national or international standards.
position within the irradiator. The uncertainty of the reference
7.2.2 Irradiation of calibration dosimeters is a critical com-
standard dosimetry system will affect the uncertainty of the
ponent of the calibration of the dosimetry system. There are
system being calibrated and thus the uncertainty in the ab-
two methods for irradiating dosimeters for calibration:
sorbed dose value for the product being irradiated.
7.2.2.1 Calibration irradiations performed at an approved
(2)Reference standard dosimetry systems may take the
form of systems held at a given location or they may take the laboratory followed by a calibration verification exercise for
form of transfer standard dosimetry systems operated by a the actual conditions of use (see ISO/ASTM 51261), and
TABLE 1 Examples of reference-standard dosimetry systems
Useful Absorbed-dose Range
Dosimeter Readout System Reference
(Gy)
Alanine EPR spectrometer 1 Gy to 10 Gy ISO/ASTM 51607
Ionization chamber Electrometer Can be easily applied to the (1)
insect irradiation dose range
© ISO/ASTM International 2022 – All rights reserved
TABLE 2 Examples of routine dosimetry systems
Useful Absorbed-dose
Dosimeter Readout System Reference
Range (Gy)
Thermoluminescence (TLD) Thermoluminescence reader 1 Gy to 10 Gy ISO/ASTM 51956
Radiochromic film (Gafchromic film) UV/visible spectrophotometer, 10 Gy to 10 Gy ISO/ASTM 51275 and
Transmission/Reflectance densitometer Ref (18,19)
Alanine EPR spectrometer 1 Gy to 10 Gy ISO/ASTM 51607
Radiochromic optical waveguide Photometric means using dual wavelength 1Gyto10 Gy ISO/ASTM 51310
photometry
The recommended steps in Table A1.1 are not meant to be exhaustive.
7.2.2.2 In-situ/in-plant calibration irradiations of routine
dosimeters along with transfer standard dosimeters issued and
8.2 Operational qualification of an irradiation facility is
analyzed by an approved laboratory.
performed to establish baseline data for evaluating irradiator
7.2.2.3 For gamma irradiators, the most commonly used
effectiveness, predictability, and reproducibility for the range
transfer standard dosimetry system is alanine-EPR. For low-
of conditions of operation for key process parameters that
energy X-ray irradiators, ionization chambers or the alanine-
affect absorbed dose in the product. As part of this process,
EPR dosimetry system may be used as transfer standard
dosimetry may, for example, be performed to: (1) establish
dosimetry systems as long as they are calibrated for the
relationships between the absorbed dose for a reference geom-
appropriate energy (1, 15, 16).
etry and the operating parameters of the irradiator, (2) measure
7.2.3 Calibration of a dosimetry system is most commonly
absorbed-dosedistributionsinirradiationcontainerscontaining
made in terms of absorbed dose to water, but absorbed dose to
homogeneous simulated product (dose mapping), (3) charac-
other materials might be used.
terize absorbed-dose variations when a facility and process
7.2.4 Calibration of the routine dosimetry system shall be
parametersfluctuatestatisticallyduringnormaloperations,and
repeated at regular intervals to ensure that the accuracy of the
(4) measure the absorbed-dose rate at a reference position
absorbed-dose measurement is maintained within required
within the irradiation container filled with insects or simulated
limits.
product.
7.3 Factors That Affect the Response of Dosimeters:
NOTE5—Specificinformationonoperationalqualificationcanbefound
in ISO/ASTM Practices 52116 (for self-contained dry-storage gamma
7.3.1 Factors that affect the response of dosimeters (gener-
facilities), 51608 (for X-ray facilities), 51649 (for electron beam
ally referred to as “influence quantities”), including environ-
facilities),and51702(forlarge-scalegammafacilities),andinRef(1)(for
mental conditions and variations of such conditions within the
self-contained low-energy X-ray facilities).
irradiator, shall be known and their effect taken into account
8.2.1 Irradiator Characterization—The absorbed dose re-
(see ISO/ASTM Practices 52628 and 52701 and the Standard
ceivedbyinsectsdependsontheirradiatorparameters(suchas
of the specific dosimetry system).
the source activity or power at the time of irradiation, the
7.3.2 Thepossiblephotonenergyrangeforinsectirradiation
geometry of the source, the source-to-product distance, the
applications is from 40 keV to 1.33 MeV. Since response of
irradiation geometry) and the process parameters (such as the
many routine dosimeters depends on the photon energy, care
irradiation time, the product composition and density, and the
mustbetak
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