ISO/ASTM 51900:2023
(Main)Guidance for dosimetry for radiation research
Guidance for dosimetry for radiation research
ISO 51900:2009 applies to the minimum requirements for dosimetry needed to conduct research on the effect of radiation on food and agricultural products. Such research includes establishment of the quantitative relationship between absorbed dose and the relevant effects in these products. ISO 51900:2009 also describes the overall requirement for dosimetry in such research, and in reporting of the results. It is necessary that dosimetry be considered as an integral part of the experiment. ISO 51900:2009 applies to research conducted using the following types of ionizing radiation: gamma radiation, X-ray (bremsstrahlung), and electron beams. The purpose of ISO 51900:2009 is to ensure that the radiation source and experimental methodology are chosen such that the results of the experiment will be useful and understandable to other scientists and regulatory agencies. ISO 51900:2009 describes dosimetry requirements for establishing the experimental method and for routine experiments; however, ISO 51900:2009 is not intended to limit the flexibility of the experimenter in the determination of the experimental methodology. ISO 51900:2009 includes tutorial information in the form of notes. ISO 51900:2009 does not include dosimetry requirements for installation qualification or operational qualification of the irradiation facility.
Lignes directrices de la dosimétrie pour la recherche dans le domaine de l’irradiation
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INTERNATIONAL ISO/ASTM
STANDARD 51900
Third edition
2023-04
Guidance for dosimetry for
radiation research
Lignes directrices de la dosimétrie pour la recherche dans le
domaine de l’irradiation
Reference number
ISO/ASTM 51900:2023(E)
© ISO/ASTM International 2023
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ISO/ASTM 51900:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO/ASTM International 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester. In the United States, such requests should be sent to ASTM International.
ISO copyright office ASTM International
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Published in Switzerland
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ISO/ASTM 51900:2023(E)
Contents Page
1 Scope. 1
2 Referenced documents. 1
3 Terminology. 2
4 Significance and use. 3
5 Irradiation facilities and modes of operation. 4
6 Radiation source characteristics. 5
7 Dosimetry systems. 5
8 Irradiator characterization. 6
9 Sample or product dose mapping. 6
10 Dosimetry during experimentation. 7
11 Documentation. 8
12 Measurement uncertainty. 8
13 Keywords. 8
Table 1 Examples of routine dosimeters (see ISO/ASTM 52628). 6
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ISO/ASTM 51900:2023(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any
patent rights identified during the development of the document will be in the Introduction and/or on
the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see
www.iso.org/iso/foreword.html.
This document was prepared by ASTM Committee E61, Radiation processing (as ASTM E1900-97), and
drafted in accordance with its editorial rules. It was assigned to Technical Committee ISO/TC 85,
Nuclear energy, nuclear technologies and radiation protection.
Any feedback or questions on this document should be directed to the user’s national standards
body. A complete listing of these bodies can be found at www.iso.org/members.html.
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
ISO/ASTM 51900:2023(E)
Standard Guidance for
1
Dosimetry for Radiation Research
This standard is issued under the fixed designation ISO/ASTM 51900; the number immediately following the designation indicates the
year of original adoption or, in the case of revision, the year of last revision.
1. Scope radiation source and experimental methodology are chosen
such that the results of the experiment will be useful and
1.1 This document covers essential recommendations for
understandable to other scientists and regulatory agencies. The
dosimetry needed to conduct research on the effects of ionizing
total uncertainty in the absorbed-dose measurement results and
radiation on materials, products and biological samples. Such
theabsorbed-dosevariationwithintheirradiatedsampleshould
research includes establishment of the quantitative relationship
be taken into account in the interpretation of the research
between absorbed dose and the relevant effects.This document
results (see ISO/ASTM Guide 51707).
also describes the overall need for dosimetry in such research,
and for reporting of the results. Dosimetry should be consid- 1.5 This document is one of a set of standards that provides
ered an integral part of the experiment, and the researcher is recommendations for properly implementing dosimetry in
responsible for ensuring the accuracy and applicability of the radiation processing, and describes a means of achieving
dosimetry system used. compliance with the requirements of ISO/ASTM 52628. This
document is thus intended to be read in conjunction with
NOTE 1—For research involving food products, note that the Codex
ISO/ASTM 52628.
Alimentarius Commission has developed an international General Stan-
dard and a Code of Practice that address the application of ionizing
1.6 This standard does not purport to address all of the
radiation to the treatment of foods and which strongly emphasizes the role
safety concerns, if any, associated with its use. It is the
2
of dosimetry for ensuring that irradiation will be properly performed (1).
responsibility of the user of this standard to establish appro-
NOTE 2—This document includes tutorial information in the form of
priate safety, health, and environmental practices and deter-
Notes. Researchers should also refer to the references provided at the end
of the standard, and other applicable scientific literature, to assist in the mine the applicability of regulatory limitations prior to use.
experimental methodology as applied to dosimetry (2-5).
1.7 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.2 This document covers research conducted using the
following types of ionizing radiation: gamma radiation (typi- ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
cally from Cobalt-60 or Cesium-137 sources), X-radiation
(bremsstrahlung, typically with energies between 50 keV and mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
7.5 MeV), and electrons (typically with energies ranging from
80 keV to more than 10 MeV). See ISO/ASTM 51608, 51649,
2. Referenced documents
51818 and 51702.
3
2.1 ASTM Standards:
1.3 This document describes dosimetry recommendations
E2232 Guide for Selection and Use of Mathematical Meth-
for establishing the experimental method. It does not include
ods for Calculating Absorbed Dose in Radiation Process-
dosimetry recommendations for installation qualification or
ing Applications
operational qualification of the irradiation facility. These sub-
E3083 Terminology Relating to Radiation Processing: Do-
jects are treated in ISO/ASTM 51608, 51649, 51818 and
simetry and Applications
51702.
3
2.2 ISO/ASTM Standards:
1.4 This document is not intended to limit the flexibility of
51205 Practice for Use of a Ceric-Cerous Sulfate Dosimetry
the researcher in the determination of the experimental meth-
System
odology. The purpose of the document is to ensure that the
51026 Practice for Using the Fricke Dosimetry System
51261 Practice for Calibration of Routine Dosimetry Sys-
tems for Radiation Processing
1
This document is under the jurisdiction ofASTM Committee E61 on Radiation
51275 Practice for Use of a Radiochromic Film Dosimetry
Processing and is the direct responsibility of Subcommittee E61.04 on Specialty
Application, and is also under the jurisdiction of ISO/TC 85/WG 3. System
Current edition approved Dec. 23, 2022. Published January 2023. Originally
published asASTM E1900–97. The present Third Edition of International Standard
3
ISO/ASTM 51900:2022(E) is a major revision of the Second Edition of ISO/ASTM For referenced ASTM and ISO/ASTM standards, visit the ASTM website,
51900:2009(E). www.astm.org, or contact ASTM Customer Service at service@astm.org. For
2
The boldface numbers in parentheses refer to the bibliography at the end of this Annual Book of ASTM Standards volume information, refer to the standard’s
document. Document Summary page on the ASTM website.
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ISO/ASTM 51900:2023(E)
8
51276 Practice for Use of a Polymethylmethacrylate Dosim- 2.6 NPL Report:
etry System CIRM 29 : Guidelines for the Calibration of Routine Dosim-
51310 Practice for Use of a Radiochromic Optical Wave- eters for use in Radiation Processing, Sharpe, P., and
guide Dosimetry System Miller, A., September, 2009.
51538 Practice for Use of the Ethanol-Chlorobenzene Do-
3. Terminology
simetry System
51607 Practice for Use of the Alanine-EPR Dosimetry Sys-
3.1 Definitions:
tem
3.1.1 absorbed dose (D)—quotient of dε by dm, where dε is
¯ ¯
51608 Practice for Dosimetry in an X-ray (Bremsstrahlung)
the mean energy imparted by ionizing radiation to matter of
Facility for Radiation Processing
incremental mass dm (ICRU 85a), thus
51649 Practice for Dosimetry in an Electron Beam Facility
D5 dε¯/dm (1)
forRadiationProcessingatEnergiesbetween300keVand
3.1.1.1 Discussion—TheSIunitofabsorbeddoseisthegray
25 MeV
(Gy),where1grayisequivalenttotheabsorptionof1jouleper
51650 Practice for Use of Cellulose Triacetate Dosimetry
kilogram of the specified material (1 Gy = 1 J/kg).
System
3.1.1.2 Discussion—For the purposes of this standard, the
51702 Practice for Dosimetry in a Gamma Facility for
term dose is used to mean “absorbed dose”.
Radiation Processing
3.1.2 absorbed-dose mapping—measurement of absorbed
51707 Guide for Estimating Uncertainties in Dosimetry for
dose within an irradiated product to produce a one-, two- or
Radiation Processing
three-dimensionaldistributionofabsorbeddose,thusrendering
51818 Guide for Dosimetry in an Electron Beam Facility for
a map of absorbed-dose values.
RadiationProcessingatEnergiesBetween80and300keV
˙
51956 Practice for Use of Thermoluminescence Dosimetry 3.1.3 absorbed-dose rate D—quotient of dD by dt, where
dD is the increment of absorbed dose in the time interval dt
(TLD) Systems for Radiation Processing
52116 Practice for Dosimetry for a Self-Contained Dry- (ICRU 85a), thus
Storage Gamma Irradiator
˙
D5 dD/dt (2)
52303 Practice for Absorbed-Dose Mapping in Radiation
3.1.3.1 Discussion—
Processing Facilities
-1
(1) The SI unit is Gy·s . However, the absorbed-dose rate
52628 Practice for Dosimetry in Radiation Processing
is often specified in terms of its average value over longer time
52701 Guide for Performance Charcterization of Dosimeters
-1 -1
intervals, for example, in units of Gy·min or Gy·h .
and Dosimetry Systems for Use in Radiation Processing
(2) In gamma industrial irradiators, dose rate may be
2.3 International Commission on Radiation Units and Mea-
significantly different at different locations where product is
4
surements (ICRU) Reports:
irradiated.
ICRU 80 Dosimetry Systems for Use in Radiation Process-
(3) In electron-beam irradiators with pulsed or scanned
ing
beam, there are two types of dose rate: average value over
ICRU 85a Fundamental Quantities and Units for Ionizing
several pulses (scans) and instantaneous value within a pulse
Radiation
(scan). These values can be significantly different.
5
2.4 ISO Standard:
3.1.4 bremsstrahlung—broad-spectrum electromagnetic ra-
12749-4 Nuclear energy, nuclear technologies, and radio-
diation emitted when an energetic charged particle is influ-
logical protection – Vocabulary – Part 4: Dosimetry for
enced by a strong electric or magnetic field, such as that in the
radiation processing
vicinity of an atomic nucleus.
2.5 Joint Committee for Guides in Metrology (JCGM)
3.1.5 dose uniformity ratio—ratio of the maximum to the
Reports:
minimum absorbed dose within the irradiated product.
JCGM 100: 2008, GUM 1995, with minor corrections,
3.1.5.1 Discussion—The concept is also referred to as the
Evaluation of measurement data – Guide to the expression
max/min dose ratio.
6
of uncertainty in measurement
3.1.6 dosimeter—device that, when irradiated, exhibits a
JCGM 200: 2012, VIM International vocabulary of metrol-
quantifiable change that can be related to absorbed dose in a
7
ogy – Basic and general concepts and associated terms
given material using appropriate measurement instruments and
procedures.
3.1.7 dosimeter response—reproducible, quantifiable
4
Available from the International Commission on Radiation Units and
change produced in the dosimeter by ionizing radiation.
Measurements, 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814 USA.
5
3.1.7.1 Discussion—
Available from International Organization for Standardization (ISO), ISO
Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier,
(1) The dosimeter response value, obtained from one or
Geneva, Switzerland, http://www.iso.org.
more measurements, is used in the estimation of the absorbed
6
Document produced by Working Group 1 of the Joint Committee for Guides in
dose.
Metrology (JCGM WWG1). Available free of charge at the BIPM website
(http://www.bipm.org).
7
Document produced by Working Group 2 of the Joint Committee for Guides in
8
Metrology (JCGM WG2), Available free of charge at the BIPM website (http:// Available from National Physical Laboratory, Online, Available:
www.bipm.org). http://www.chemdos.npl.co.uk/docs/NPLReportCIRM29.pdf. 8 May 2019.
© ISO/ASTM International 2023 – All rights reserved
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ISO/ASTM 51900:2023(E)
(2) The response value might be obtained from such the measurement model, estimates, and measurement uncer-
measurements as optical absorbance, peak-to-peak distance in tainties associated with the quantities in the measurement
EPR spectra, or electropotential between solutions. model, covariances, type of applied probability density
functions, degrees of freedom, type of evaluation of measure-
3.1.8 dosimetry system—interrelatedelementsusedformea-
ment uncertainty, and any coverage factor.
suring absorbed dose, consisting of dosimeters, measurement
instruments and their associated reference standards, and 3.1.18 X-radiation—ionizing electromagnetic radiation,
which includes both bremsstrahlung and the characteristic
procedures for the system’s use.
radiation emitted when atomic electrons make transitions to
3.1.9 measurement uncertainty—non-negative parameter
more tightly bound states.
characterizing the dispersion of the quantity values being
3.1.18.1 Discussion—In radiation processing applications,
attributed to a measurand, based on the information used
the principal X-radiation is bremsstrahlung.
(VIM).
3.2 Definitions of Terms Specific to This Standard:
3.1.10 metrological traceability—property of a measure-
3.2.1 nominal dose——absorbed dose intended for the vol-
ment whereby the result can be related to a reference through
ume of interest within the irradiated sample.
a documented unbroken chain of calibrations, each contribut-
ing to the measurement uncertainty (VIM).
NOTE 3—Definitions of other terms used in this standard that pertain to
3.1.10.1 Discussion—
radiationmeasurementanddosimetrymaybefoundinISO/ASTM52628,
ASTM Terminology E3083, and ISO 12749-4. Definitions in these
(1) The unbroken chain of calibrations is referred to as
documents are compatible with ICRU Report 85a, and therefore, may be
“traceability chain”.
used as alternative references. Where appropriate, definitions used in this
(2) It is also sometimes referred to as “measurement
standard have been derived from, and are consistent with, general
traceability”.
metrological definitions given in the VIM.
3.1.11 repeatability (of results of measurements)—closeness
4. Significance and use
of the agreement between the results of successive measure-
ments of the same measurand carried out under the same
4.1 Reliable dosimetry is indispensable for research on the
conditions of measurement (GUM).
effects of ionizing radiation on materials and products.Without
3.1.11.1 Discussion—
reliable dosimetry valid conclusions cannot be reached, or the
(1) These conditions are called “repeatability conditions”.
wrong conclusions might be reached.
(2) Repeatability conditions include: the same measure-
4.2 This document is intended to provide direction on how
ment procedure, the same observer, the same measuring
to conduct dosimetry for research and experiments on the
instrument used under the same conditions, the same location,
effects of ionizing radiation on materials and products, and on
repetition over a short period of time.
the reporting of dosimetry results. Requirements on dosimetry
(3) Repeatability might be expressed quantitatively in
and on dose ranges might differ between the various types of
terms of the dispersion characteristics of the results, such as
experiments to be carried out.
standard deviation.
4.3 Proper reporting of the manner in which the irradiation
3.1.12 reproducibility (of results of measurements)—
was carried out is important since the degree of radiation effect
closenessofagreementbetweentheresultsofmeasurementsof
might be a function of various factors, other than absorbed
the same measurand carried out under changed conditions of
dose, such as the radiation source, the absorbed-dose rate,
measurements (GUM).
energy of the incident radiation, ambient environmental con-
3.1.13 routine dosimetry system—dosimetry system cali-
ditions during irradiation, and the type of incident radiation.
brated against a reference standard dosimetry system and used
This document attempts to highlight the information, including
for routine absorbed dose measurements, including dose map-
the methodology and results of the absorbed-dose
ping and process monitoring.
measurements, necessary for an experiment to be repeatable by
3.1.14 simulated product—material with radiation absorp-
other researchers.
tion and scattering properties similar to those of the product,
4.4 In most cases an experiment should be designed to
material or substance to be irradiated.
irradiate the sample as uniformly as possible. In practice, a
3.1.15 transfer standard dosimetry system—dosimetry sys-
certain variation in absorbed dose will exist throughout the
tem used as an intermediary to calibrate other dosimetry
sample. Absorbed-dose mapping is used to determine the
systems.
magnitude, location, and reproducibility of the maximum
(D ) and minimum absorbed dose (D ) for a given set of
3.1.16 transit dose—absorbed dose delivered to a product
max min
(or a dosimeter) while it travels between the non-irradiation experimental parameters. Dosimeters used for dose mapping
must be capable of operation over the expected range of doses
position and the irradiation position, or in the case of a
movable source while the source moves into and out of its and must have sufficient spatial resolution to determine likely
dose gradients (see ISO/ASTM 52303).
irradiation position.
3.1.17 uncertainty budget—statement of a measurement 4.5 Computer simulations might provide useful information
uncertainty, of the components of that measurement about absorbed-dose distribution in the irradiated sample,
uncertainty, and of their calculation and combination (VIM).
especially near material interfaces (seeASTM E2232), but are
3.1.17.1 Discussion—An uncertainty budget should include not a substitute for dosimetry.
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ISO/ASTM 51900:2023(E)
60
5. Irradiation facilities and modes of operation Coandcanberaisedorloweredintoalargeirradiationroom.
NOTE 4—This section is considered relevant for the user who has little
When retracted from the irradiation room, the source is
prior knowledge in the field.
shielded by water (pool-type), or an appropriate material of
NOTE 5—Sections 5 and 6 give a brief overview of types of irradiation
high atomic number (dry-storage), or both.
facilities and radiation source characteristics. Radiation source
5.5.1 Automatic Operation—A common method of irradia-
characteristics, the type of radiation produced, the energy of the photons
tion is sample containers to be automatically conveyed into the
or electrons, and the size and density of the samples to be irradiated will
all be factors in determining how the incident radiation is absorbed in the
irradiation room and then circulated through multiple positions
irradiated samples. Researchers unfamiliar with radiation source charac-
around a central source in order to obtain a uniform absorbed
teristics are strongly encouraged to review appropriate reference materials
dose. Samples are automatically conveyed out of the irradia-
before beginning experimentation (2-5).
tion room, allowing the source to remain exposed for continu-
5.1 Types of Facilities—This document covers the use of
ousoperation.Thesourceisretractedfromtheirradiationroom
gamma radiation, X-radiation (bremsstrahlung), and
when the irradiator is not in use.
accelerated-electron irradiators for studying the effects of
5.5.2 Batch Operation—An alternative approach is to place
ionizing radiation on materials and products.
oneormoresamplecontainersintheirradiationroomwhilethe
5.2 Self-Contained Dry Storage Gamma Irradiators—Much source is shielded, and move the source into the irradiation
of the research currently being conducted on food and other
position for the time required to achieve the desired absorbed
products is accomplished by using gamma radiation from dose. Depending on the design of the batch irradiator, the
137 60
either Cs or Co self-contained irradiators. These devices
samples may circulate through multiple positions around the
are self-shielded using lead (or other appropriate high atomic source, or may rotate in a fixed position relative to the source,
number material), and usually have a mechanism to move the
or may be irradiated statically and repositioned one or more
sample container from the loading position to the irradiation times during the exposure period. The source is retracted from
position. See ISO/ASTM 52116. the irradiator room in order to remove the samples.
5.5.3 Large-scale gamma irradiation facilities might be
NOTE 6—Typically, self-contained dry storage gamma irradiators have
equipped with so-called “research loops” that allow irradiation
a limited irradiation volume.
of samples for test and research purposes.
5.2.1 In self-contained gamma irradiators, it is common that
5.6 Large-Scale Electron and X-ray (Bremsstrahlung) Fa-
radiation sources are placed in an annular array around an
cilities:
irradiation container, such that the absorbed dose is relatively
uniform in the irradiated samples. 5.6.1 Electron Facility—Radiation sources for electrons
(with energies greater than 300 keV) are either direct action
5.2.2 Another method is to rotate the irradiation container
(potential-drop)orindirect-action(microwave-powered)accel-
on an irradiator turntable within the radiation field to achieve a
erators. The radiation fields depend on the characteristics and
relatively uniform dose within the sample.
the design of the accelerators. Included among these charac-
5.3 Self-Contained Wet Storage Gamma Irradiators—
teristics are the electron beam parameters (such as, the electron
Irradiation of samples may also be carried out in a wet-storage
energy spectrum, average electron beam current and beam
gamma irradiator used for large scale processing. The samples
current distribution on the product surface) that could affect
to be irradiated are kept dry in a specially designed container
dosimetry.
and lowered into the water next to the radiation source for
5.6.1.1 Typically, accelerators produce a narrow beam of
irradiation of the samples.
electrons that is scanned to cover the width of the conveyor,
5.4 Self-Contained Low-energy X-ray Irradiators—These
which is where samples are irradiated. As an alternative to
irradiators generally consist of an electron source, an electro-
scanning, the beam might be diffused using a defocusing lens
static field to accelerate these electrons, and a converter to
or scattering foils.
generate X-radiation. (See for example Ref (6)).
5.6.1.2 Electron facilities with energies less than 300 keV
5.4.1 One type of X-ray system operates a batch process
are typically direct action (potential-drop) accelerators. These
where several containers with material for test are placed
accelerators often use extended cathodes to produce extended
around and parallel to an isotropic X-ray source, and revolve
beams.
around this source during irradiation while maintaining their
5.6.2 X-ray (Bremsstrahlung) Facility—An X-ray
orientation (much like chairs on a Ferris wheel), achieving
(bremsstrahlung) generator emits short-wavelength electro-
acceptable dose uniformity (6, 7).
magnetic radiation, which is analogous to gamma radiation
5.4.2 Alternately, a batch process may be operated where
from radioactive isotopic sources. Although their effects on
one or more containers are placed on a turntable which rotates
irradiated materials might be similar, they differ in their energy
the material for test next to a directional X-ray source.
spectra, angular distribution, and dose rates.
5.4.3 Another method is to continuously pass trays or flat
5.6.2.1 Electrons are accelerated towards a metal target or
boxes between two X-ray sources, providing irradiation from
“converter” of high atomic number (typically tungsten or
two sides.
tantalum). The collision of the electrons with the target
generates X-radiation with a broad continuous energy spec-
5.5 Large-scale Gamma Irradiation Facilities—Gamma ir-
radiation of research samples is also carried out in large-scale trum.
irradiators, either pool-type or dry-storage. In these facilities 5.6.3 Sample Transport—Samples are typically carried on a
the source typically consists of a series of rods that contain conveyor through the radiation field. Because of the narrow
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ISO/ASTM 51900:2023(E)
angular distribution of the radiation, use of conveyors to 6.3.1.1 Direct-action electron accelerators employ direct
transport samples through the irradiation field enhances the current (dc) or pulsed high-voltage generators and typically
dose uniformity in the sample. produce electron energies up to 5 MeV.
6.3.1.2 Indirect-action electron accelerators use microwave
5.6.4 Refer to ISO/ASTM 51608, 51818 and 51649 for
more detailed information on electron and X-ray (bremsstrahl- or very high frequency to produce electron energies typically
from 1 MeV to 20 MeV
ung) facilities and modes of operation.
6.3.2 For an X-ray (bremsstrahlung) facility, along with
6. Radiation source characteristics beam charact
...
INTERNATIONAL ISO/ASTM
STANDARD 51900
Third edition
Guidance for dosimetry for
radiation research
Lignes directrices de la dosimétrie pour la recherche dans le
domaine de l’irradiation
PROOF/ÉPREUVE
Reference number
ISO/ASTM 51900:2023(E)
© ISO/ASTM International 2023
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ISO/ASTM 51900:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO/ASTM International 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester. In the United States, such requests should be sent to ASTM International.
ISO copyright office ASTM International
CP 401 • Ch. de Blandonnet 8 100 Barr Harbor Drive, PO Box C700
CH-1214 Vernier, Geneva West Conshohocken, PA 19428-2959, USA
Phone: +41 22 749 01 11 Phone: +610 832 9634
Fax: +610 832 9635
Email: copyright@iso.org Email: khooper@astm.org
Website: www.iso.org Website: www.astm.org
Published in Switzerland
ii
PROOF/ÉPREUVE © ISO/ASTM International 2023 – All rights reserved
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ISO/ASTM 51900:2023(E)
Contents Page
1 Scope. 1
2 Referenced documents. 1
3 Terminology. 2
4 Significance and use. 3
5 Irradiation facilities and modes of operation. 4
6 Radiation source characteristics. 5
7 Dosimetry systems. 5
8 Irradiator characterization. 6
9 Sample or product dose mapping. 6
10 Dosimetry during experimentation. 7
11 Documentation. 8
12 Measurement uncertainty. 8
13 Keywords. 8
Table 1 Examples of routine dosimeters (see ISO/ASTM 52628). 6
© ISO/ASTM International 2023 – All rights reserved iii
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ISO/ASTM 51900:2023(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any
patent rights identified during the development of the document will be in the Introduction and/or on
the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see
www.iso.org/iso/foreword.html.
This document was prepared by ASTM Committee E61, Radiation processing (as ASTM E1900-97), and
drafted in accordance with its editorial rules. It was assigned to Technical Committee ISO/TC 85,
Nuclear energy, nuclear technologies and radiation protection.
Any feedback or questions on this document should be directed to the user’s national standards
body. A complete listing of these bodies can be found at www.iso.org/members.html.
iv © ISO/ASTM International 2023 – All rights reserved
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
ISO/ASTM 51900:2023(E)
Standard Guidance for
1
Dosimetry for Radiation Research
This standard is issued under the fixed designation ISO/ASTM 51900; the number immediately following the designation indicates the
year of original adoption or, in the case of revision, the year of last revision.
1. Scope radiation source and experimental methodology are chosen
such that the results of the experiment will be useful and
1.1 This document covers essential recommendations for
understandable to other scientists and regulatory agencies. The
dosimetry needed to conduct research on the effects of ionizing
total uncertainty in the absorbed-dose measurement results and
radiation on materials, products and biological samples. Such
theabsorbed-dosevariationwithintheirradiatedsampleshould
research includes establishment of the quantitative relationship
be taken into account in the interpretation of the research
between absorbed dose and the relevant effects.This document
results (see ISO/ASTM Guide 51707).
also describes the overall need for dosimetry in such research,
and for reporting of the results. Dosimetry should be consid- 1.5 This document is one of a set of standards that provides
ered an integral part of the experiment, and the researcher is recommendations for properly implementing dosimetry in
responsible for ensuring the accuracy and applicability of the radiation processing, and describes a means of achieving
dosimetry system used. compliance with the requirements of ISO/ASTM 52628. This
document is thus intended to be read in conjunction with
NOTE 1—For research involving food products, note that the Codex
ISO/ASTM 52628.
Alimentarius Commission has developed an international General Stan-
dard and a Code of Practice that address the application of ionizing
1.6 This standard does not purport to address all of the
radiation to the treatment of foods and which strongly emphasizes the role
safety concerns, if any, associated with its use. It is the
2
of dosimetry for ensuring that irradiation will be properly performed (1).
responsibility of the user of this standard to establish appro-
NOTE 2—This document includes tutorial information in the form of
priate safety, health, and environmental practices and deter-
Notes. Researchers should also refer to the references provided at the end
of the standard, and other applicable scientific literature, to assist in the mine the applicability of regulatory limitations prior to use.
experimental methodology as applied to dosimetry (2-5).
1.7 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.2 This document covers research conducted using the
following types of ionizing radiation: gamma radiation (typi- ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
cally from Cobalt-60 or Cesium-137 sources), X-radiation
(bremsstrahlung, typically with energies between 50 keV and mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
7.5 MeV), and electrons (typically with energies ranging from
80 keV to more than 10 MeV). See ISO/ASTM 51608, 51649,
2. Referenced documents
51818 and 51702.
3
2.1 ASTM Standards:
1.3 This document describes dosimetry recommendations
E2232 Guide for Selection and Use of Mathematical Meth-
for establishing the experimental method. It does not include
ods for Calculating Absorbed Dose in Radiation Process-
dosimetry recommendations for installation qualification or
ing Applications
operational qualification of the irradiation facility. These sub-
E3083 Terminology Relating to Radiation Processing: Do-
jects are treated in ISO/ASTM 51608, 51649, 51818 and
simetry and Applications
51702.
3
2.2 ISO/ASTM Standards:
1.4 This document is not intended to limit the flexibility of
51205 Practice for Use of a Ceric-Cerous Sulfate Dosimetry
the researcher in the determination of the experimental meth-
System
odology. The purpose of the document is to ensure that the
51026 Practice for Using the Fricke Dosimetry System
51261 Practice for Calibration of Routine Dosimetry Sys-
tems for Radiation Processing
1
This document is under the jurisdiction ofASTM Committee E61 on Radiation
51275 Practice for Use of a Radiochromic Film Dosimetry
Processing and is the direct responsibility of Subcommittee E61.04 on Specialty
Application, and is also under the jurisdiction of ISO/TC 85/WG 3. System
Current edition approved Dec. 23, 2022. Published January 2023. Originally
published asASTM E1900–97. The present Third Edition of International Standard
3
ISO/ASTM 51900:2022(E) is a major revision of the Second Edition of ISO/ASTM For referenced ASTM and ISO/ASTM standards, visit the ASTM website,
51900:2009(E). www.astm.org, or contact ASTM Customer Service at service@astm.org. For
2
The boldface numbers in parentheses refer to the bibliography at the end of this Annual Book of ASTM Standards volume information, refer to the standard’s
document. Document Summary page on the ASTM website.
© ISO/ASTM International 2023 – All rights reserved
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ISO/ASTM 51900:2023(E)
8
51276 Practice for Use of a Polymethylmethacrylate Dosim- 2.6 NPL Report:
etry System CIRM 29 : Guidelines for the Calibration of Routine Dosim-
51310 Practice for Use of a Radiochromic Optical Wave- eters for use in Radiation Processing, Sharpe, P., and
guide Dosimetry System Miller, A., September, 2009.
51538 Practice for Use of the Ethanol-Chlorobenzene Do-
3. Terminology
simetry System
51607 Practice for Use of the Alanine-EPR Dosimetry Sys-
3.1 Definitions:
tem
3.1.1 absorbed dose (D)—quotient of dε by dm, where dε is
¯ ¯
51608 Practice for Dosimetry in an X-ray (Bremsstrahlung)
the mean energy imparted by ionizing radiation to matter of
Facility for Radiation Processing
incremental mass dm (ICRU 85a), thus
51649 Practice for Dosimetry in an Electron Beam Facility
D5 dε¯/dm (1)
forRadiationProcessingatEnergiesbetween300keVand
3.1.1.1 Discussion—TheSIunitofabsorbeddoseisthegray
25 MeV
(Gy),where1grayisequivalenttotheabsorptionof1jouleper
51650 Practice for Use of Cellulose Triacetate Dosimetry
kilogram of the specified material (1 Gy = 1 J/kg).
System
3.1.1.2 Discussion—For the purposes of this standard, the
51702 Practice for Dosimetry in a Gamma Facility for
term dose is used to mean “absorbed dose”.
Radiation Processing
3.1.2 absorbed-dose mapping—measurement of absorbed
51707 Guide for Estimating Uncertainties in Dosimetry for
dose within an irradiated product to produce a one-, two- or
Radiation Processing
three-dimensionaldistributionofabsorbeddose,thusrendering
51818 Guide for Dosimetry in an Electron Beam Facility for
a map of absorbed-dose values.
RadiationProcessingatEnergiesBetween80and300keV
˙
51956 Practice for Use of Thermoluminescence Dosimetry 3.1.3 absorbed-dose rate D—quotient of dD by dt, where
dD is the increment of absorbed dose in the time interval dt
(TLD) Systems for Radiation Processing
52116 Practice for Dosimetry for a Self-Contained Dry- (ICRU 85a), thus
Storage Gamma Irradiator
˙
D5 dD/dt (2)
52303 Practice for Absorbed-Dose Mapping in Radiation
3.1.3.1 Discussion—
Processing Facilities
-1
(1) The SI unit is Gy·s . However, the absorbed-dose rate
52628 Practice for Dosimetry in Radiation Processing
is often specified in terms of its average value over longer time
52701 Guide for Performance Charcterization of Dosimeters
-1 -1
intervals, for example, in units of Gy·min or Gy·h .
and Dosimetry Systems for Use in Radiation Processing
(2) In gamma industrial irradiators, dose rate may be
2.3 International Commission on Radiation Units and Mea-
significantly different at different locations where product is
4
surements (ICRU) Reports:
irradiated.
ICRU 80 Dosimetry Systems for Use in Radiation Process-
(3) In electron-beam irradiators with pulsed or scanned
ing
beam, there are two types of dose rate: average value over
ICRU 85a Fundamental Quantities and Units for Ionizing
several pulses (scans) and instantaneous value within a pulse
Radiation
(scan). These values can be significantly different.
5
2.4 ISO Standard:
3.1.4 bremsstrahlung—broad-spectrum electromagnetic ra-
12749-4 Nuclear energy, nuclear technologies, and radio-
diation emitted when an energetic charged particle is influ-
logical protection – Vocabulary – Part 4: Dosimetry for
enced by a strong electric or magnetic field, such as that in the
radiation processing
vicinity of an atomic nucleus.
2.5 Joint Committee for Guides in Metrology (JCGM)
3.1.5 dose uniformity ratio—ratio of the maximum to the
Reports:
minimum absorbed dose within the irradiated product.
JCGM 100: 2008, GUM 1995, with minor corrections,
3.1.5.1 Discussion—The concept is also referred to as the
Evaluation of measurement data – Guide to the expression
max/min dose ratio.
6
of uncertainty in measurement
3.1.6 dosimeter—device that, when irradiated, exhibits a
JCGM 200: 2012, VIM International vocabulary of metrol-
quantifiable change that can be related to absorbed dose in a
7
ogy – Basic and general concepts and associated terms
given material using appropriate measurement instruments and
procedures.
3.1.7 dosimeter response—reproducible, quantifiable
4
Available from the International Commission on Radiation Units and
change produced in the dosimeter by ionizing radiation.
Measurements, 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814 USA.
5
3.1.7.1 Discussion—
Available from International Organization for Standardization (ISO), ISO
Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier,
(1) The dosimeter response value, obtained from one or
Geneva, Switzerland, http://www.iso.org.
more measurements, is used in the estimation of the absorbed
6
Document produced by Working Group 1 of the Joint Committee for Guides in
dose.
Metrology (JCGM WWG1). Available free of charge at the BIPM website
(http://www.bipm.org).
7
Document produced by Working Group 2 of the Joint Committee for Guides in
8
Metrology (JCGM WG2), Available free of charge at the BIPM website (http:// Available from National Physical Laboratory, Online, Available:
www.bipm.org). http://www.chemdos.npl.co.uk/docs/NPLReportCIRM29.pdf. 8 May 2019.
© ISO/ASTM International 2023 – All rights reserved
2
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ISO/ASTM 51900:2023(E)
(2) The response value might be obtained from such the measurement model, estimates, and measurement uncer-
measurements as optical absorbance, peak-to-peak distance in tainties associated with the quantities in the measurement
EPR spectra, or electropotential between solutions. model, covariances, type of applied probability density
functions, degrees of freedom, type of evaluation of measure-
3.1.8 dosimetry system—interrelatedelementsusedformea-
ment uncertainty, and any coverage factor.
suring absorbed dose, consisting of dosimeters, measurement
instruments and their associated reference standards, and 3.1.18 X-radiation—ionizing electromagnetic radiation,
which includes both bremsstrahlung and the characteristic
procedures for the system’s use.
radiation emitted when atomic electrons make transitions to
3.1.9 measurement uncertainty—non-negative parameter
more tightly bound states.
characterizing the dispersion of the quantity values being
3.1.18.1 Discussion—In radiation processing applications,
attributed to a measurand, based on the information used
the principal X-radiation is bremsstrahlung.
(VIM).
3.2 Definitions of Terms Specific to This Standard:
3.1.10 metrological traceability—property of a measure-
3.2.1 nominal dose——absorbed dose intended for the vol-
ment whereby the result can be related to a reference through
ume of interest within the irradiated sample.
a documented unbroken chain of calibrations, each contribut-
ing to the measurement uncertainty (VIM).
NOTE 3—Definitions of other terms used in this standard that pertain to
3.1.10.1 Discussion—
radiationmeasurementanddosimetrymaybefoundinISO/ASTM52628,
ASTM Terminology E3083, and ISO 12749-4. Definitions in these
(1) The unbroken chain of calibrations is referred to as
documents are compatible with ICRU Report 85a, and therefore, may be
“traceability chain”.
used as alternative references. Where appropriate, definitions used in this
(2) It is also sometimes referred to as “measurement
standard have been derived from, and are consistent with, general
traceability”.
metrological definitions given in the VIM.
3.1.11 repeatability (of results of measurements)—closeness
4. Significance and use
of the agreement between the results of successive measure-
ments of the same measurand carried out under the same
4.1 Reliable dosimetry is indispensable for research on the
conditions of measurement (GUM).
effects of ionizing radiation on materials and products.Without
3.1.11.1 Discussion—
reliable dosimetry valid conclusions cannot be reached, or the
(1) These conditions are called “repeatability conditions”.
wrong conclusions might be reached.
(2) Repeatability conditions include: the same measure-
4.2 This document is intended to provide direction on how
ment procedure, the same observer, the same measuring
to conduct dosimetry for research and experiments on the
instrument used under the same conditions, the same location,
effects of ionizing radiation on materials and products, and on
repetition over a short period of time.
the reporting of dosimetry results. Requirements on dosimetry
(3) Repeatability might be expressed quantitatively in
and on dose ranges might differ between the various types of
terms of the dispersion characteristics of the results, such as
experiments to be carried out.
standard deviation.
4.3 Proper reporting of the manner in which the irradiation
3.1.12 reproducibility (of results of measurements)—
was carried out is important since the degree of radiation effect
closenessofagreementbetweentheresultsofmeasurementsof
might be a function of various factors, other than absorbed
the same measurand carried out under changed conditions of
dose, such as the radiation source, the absorbed-dose rate,
measurements (GUM).
energy of the incident radiation, ambient environmental con-
3.1.13 routine dosimetry system—dosimetry system cali-
ditions during irradiation, and the type of incident radiation.
brated against a reference standard dosimetry system and used
This document attempts to highlight the information, including
for routine absorbed dose measurements, including dose map-
the methodology and results of the absorbed-dose
ping and process monitoring.
measurements, necessary for an experiment to be repeatable by
3.1.14 simulated product—material with radiation absorp-
other researchers.
tion and scattering properties similar to those of the product,
4.4 In most cases an experiment should be designed to
material or substance to be irradiated.
irradiate the sample as uniformly as possible. In practice, a
3.1.15 transfer standard dosimetry system—dosimetry sys-
certain variation in absorbed dose will exist throughout the
tem used as an intermediary to calibrate other dosimetry
sample. Absorbed-dose mapping is used to determine the
systems.
magnitude, location, and reproducibility of the maximum
(D ) and minimum absorbed dose (D ) for a given set of
3.1.16 transit dose—absorbed dose delivered to a product
max min
(or a dosimeter) while it travels between the non-irradiation experimental parameters. Dosimeters used for dose mapping
must be capable of operation over the expected range of doses
position and the irradiation position, or in the case of a
movable source while the source moves into and out of its and must have sufficient spatial resolution to determine likely
dose gradients (see ISO/ASTM 52303).
irradiation position.
3.1.17 uncertainty budget—statement of a measurement 4.5 Computer simulations might provide useful information
uncertainty, of the components of that measurement about absorbed-dose distribution in the irradiated sample,
uncertainty, and of their calculation and combination (VIM).
especially near material interfaces (seeASTM E2232), but are
3.1.17.1 Discussion—An uncertainty budget should include not a substitute for dosimetry.
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ISO/ASTM 51900:2023(E)
60
5. Irradiation facilities and modes of operation Coandcanberaisedorloweredintoalargeirradiationroom.
NOTE 4—This section is considered relevant for the user who has little
When retracted from the irradiation room, the source is
prior knowledge in the field.
shielded by water (pool-type), or an appropriate material of
NOTE 5—Sections 5 and 6 give a brief overview of types of irradiation
high atomic number (dry-storage), or both.
facilities and radiation source characteristics. Radiation source
5.5.1 Automatic Operation—A common method of irradia-
characteristics, the type of radiation produced, the energy of the photons
tion is sample containers to be automatically conveyed into the
or electrons, and the size and density of the samples to be irradiated will
all be factors in determining how the incident radiation is absorbed in the
irradiation room and then circulated through multiple positions
irradiated samples. Researchers unfamiliar with radiation source charac-
around a central source in order to obtain a uniform absorbed
teristics are strongly encouraged to review appropriate reference materials
dose. Samples are automatically conveyed out of the irradia-
before beginning experimentation (2-5).
tion room, allowing the source to remain exposed for continu-
5.1 Types of Facilities—This document covers the use of
ousoperation.Thesourceisretractedfromtheirradiationroom
gamma radiation, X-radiation (bremsstrahlung), and
when the irradiator is not in use.
accelerated-electron irradiators for studying the effects of
5.5.2 Batch Operation—An alternative approach is to place
ionizing radiation on materials and products.
oneormoresamplecontainersintheirradiationroomwhilethe
5.2 Self-Contained Dry Storage Gamma Irradiators—Much source is shielded, and move the source into the irradiation
of the research currently being conducted on food and other
position for the time required to achieve the desired absorbed
products is accomplished by using gamma radiation from dose. Depending on the design of the batch irradiator, the
137 60
either Cs or Co self-contained irradiators. These devices
samples may circulate through multiple positions around the
are self-shielded using lead (or other appropriate high atomic source, or may rotate in a fixed position relative to the source,
number material), and usually have a mechanism to move the
or may be irradiated statically and repositioned one or more
sample container from the loading position to the irradiation times during the exposure period. The source is retracted from
position. See ISO/ASTM 52116. the irradiator room in order to remove the samples.
5.5.3 Large-scale gamma irradiation facilities might be
NOTE 6—Typically, self-contained dry storage gamma irradiators have
equipped with so-called “research loops” that allow irradiation
a limited irradiation volume.
of samples for test and research purposes.
5.2.1 In self-contained gamma irradiators, it is common that
5.6 Large-Scale Electron and X-ray (Bremsstrahlung) Fa-
radiation sources are placed in an annular array around an
cilities:
irradiation container, such that the absorbed dose is relatively
uniform in the irradiated samples. 5.6.1 Electron Facility—Radiation sources for electrons
(with energies greater than 300 keV) are either direct action
5.2.2 Another method is to rotate the irradiation container
(potential-drop)orindirect-action(microwave-powered)accel-
on an irradiator turntable within the radiation field to achieve a
erators. The radiation fields depend on the characteristics and
relatively uniform dose within the sample.
the design of the accelerators. Included among these charac-
5.3 Self-Contained Wet Storage Gamma Irradiators—
teristics are the electron beam parameters (such as, the electron
Irradiation of samples may also be carried out in a wet-storage
energy spectrum, average electron beam current and beam
gamma irradiator used for large scale processing. The samples
current distribution on the product surface) that could affect
to be irradiated are kept dry in a specially designed container
dosimetry.
and lowered into the water next to the radiation source for
5.6.1.1 Typically, accelerators produce a narrow beam of
irradiation of the samples.
electrons that is scanned to cover the width of the conveyor,
5.4 Self-Contained Low-energy X-ray Irradiators—These
which is where samples are irradiated. As an alternative to
irradiators generally consist of an electron source, an electro-
scanning, the beam might be diffused using a defocusing lens
static field to accelerate these electrons, and a converter to
or scattering foils.
generate X-radiation. (See for example Ref (6)).
5.6.1.2 Electron facilities with energies less than 300 keV
5.4.1 One type of X-ray system operates a batch process
are typically direct action (potential-drop) accelerators. These
where several containers with material for test are placed
accelerators often use extended cathodes to produce extended
around and parallel to an isotropic X-ray source, and revolve
beams.
around this source during irradiation while maintaining their
5.6.2 X-ray (Bremsstrahlung) Facility—An X-ray
orientation (much like chairs on a Ferris wheel), achieving
(bremsstrahlung) generator emits short-wavelength electro-
acceptable dose uniformity (6, 7).
magnetic radiation, which is analogous to gamma radiation
5.4.2 Alternately, a batch process may be operated where
from radioactive isotopic sources. Although their effects on
one or more containers are placed on a turntable which rotates
irradiated materials might be similar, they differ in their energy
the material for test next to a directional X-ray source.
spectra, angular distribution, and dose rates.
5.4.3 Another method is to continuously pass trays or flat
5.6.2.1 Electrons are accelerated towards a metal target or
boxes between two X-ray sources, providing irradiation from
“converter” of high atomic number (typically tungsten or
two sides.
tantalum). The collision of the electrons with the target
generates X-radiation with a broad continuous energy spec-
5.5 Large-scale Gamma Irradiation Facilities—Gamma ir-
radiation of research samples is also carried out in large-scale trum.
irradiators, either pool-type or dry-storage. In these facilities 5.6.3 Sample Transport—Samples are typically carried on a
the source typically consists of a series of rods that contain conveyor through the radiation field. Because of the narrow
© ISO/ASTM International 2023 – All rights reserved
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ISO/ASTM 51900:2023(E)
angular distribution of the radiation, use of conveyors to 6.3.1.1 Direct-action electron accelerators employ direct
transport samples through the irradiation field enhances the current (dc) or pulsed high-voltage generators and typically
dose uniformity in the sample. produce electron energies up to 5 MeV.
6.3.1.2 Indirect-action electron accelerators use microwave
5.6.4 Refer to ISO/ASTM 51608, 51818 and 51649 for
more detailed information on electron and X-ray (bremsstrahl- or very high frequency to produce electron energies typically
from 1 MeV to 20 MeV
ung) facilities and modes of operation.
6.3.2 For an X-ray (bremsstrahlung) facility, along with
6. Radiation source character
...
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