ISO/ASTM 51900:2002

Guide for dosimetry in radiation research on food and agricultural products

ISO/ASTM 15900 covers the minimum requirements for dosimetry and absorbed-dose validation needed to conduct research on the irradiation of food and agricultural products. Such research includes establishment of the quantitative relationship between the absorbed dose and the relevant effects in these products. This International Standard also describes the overall need for dosimetry in such research, and in the reporting of results. ISO/ASTM 15900 is intended for use by research scientists in the food and agricultural communities and not just scientists conducting irradiation research. It therefore includes more tutorial information than most other ASTM and ISO/ASTM dosimetry standards for radiation processing. It is in no way intended to limit the flexibility of the experimenter in the experimental design. However, the radiation source and experimental set-up should be chosen such that the results of the experiment will be beneficial and understandable to other scientists, regulatory agencies, and the food and agricultural communities. This International Standard covers research conducted using the following types of ionizing radiation: gamma rays, bremsstrahlung X-rays and electron beams but does not include other aspects of radiation processing research, such as planning of the experimental design.

Guide de la dosimétrie pour la recherche dans le domaine de l'irradiation des produits alimentaires et agricoles

General Information

• Status: Withdrawn
• Publication Date: 17-Apr-2002
• Withdrawal Date: 17-Apr-2002
• ICS: 17.240 - Radiation measurements
• ICS: 67.020 - Processes in the food industry
• 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
• Completion Date: 07-Jul-2009

Relations

• Revised: ISO/ASTM 51900:2009 - Guide for dosimetry in radiation research on food and agricultural products
• Effective Date: 15-Apr-2008

Standards Content (Sample)

INTERNATIONAL ISO/ASTM
STANDARD 51900
First edition
2002-03-15
Guide for dosimetry in radiation research
on food and agricultural products
Guide de la dosimétrie pour la recherche dans le domaine de
l’irradiation des produits alimentaires et agricoles
Reference number
ISO/ASTM 51900:2002(E)
© ISO/ASTM International 2002

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ISO/ASTM 51900:2002(E)
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ii © ISO/ASTM International 2002 – All rights reserved

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ISO/ASTM 51900:2002(E)
Contents Page
1 Scope . 1
2 Referenced documents . 1
3 Terminology . 2
4 Significance and use . 3
5 Types of facilities and modes of operation . 4
6 Radiation source characteristics . 4
7 Dosimetry systems . 5
8 Radiation–sensitive indicators . 5
9 Experimental design . 6
10 Routine dosimetry following the experiment set-up . 7
11 Documentation . 8
12 Measurement uncertainty . 9
13 Keywords . 9
Bibliography . 9
© ISO/ASTM International 2002 – All rights reserved iii

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ISO/ASTM 51900:2002(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.
Draft International Standards adopted by the technical committees are circulated to the member bodies for
voting. Publication as an International Standard requires approval by at least 75% of the member bodies
casting a vote.
ASTM International is one of the world’s largest voluntary standards development organizations with global
participation from affected stakeholders. ASTM technical committees follow rigorous due process balloting
procedures.
A pilot project between ISO and ASTM International has been formed to develop and maintain a group of
ISO/ASTM radiation processing dosimetry standards. Under this pilot project, ASTM Subcommittee E10.01,
Dosimetry for Radiation Processing, is responsible for the development and maintenance of these dosimetry
standards with unrestricted participation and input from appropriate ISO member bodies.
Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. Neither ISO nor ASTM International shall be held responsible for identifying any or all such
patent rights.
International Standard ISO/ASTM 51900 was developed by ASTM Committee E10, Nuclear Technology and
Applications, through Subcommittee E10.01, and by Technical Committee ISO/TC 85, Nuclear Energy.
iv © ISO/ASTM International 2002 – All rights reserved

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ISO/ASTM 51900:2002(E)
Standard Guide for
Dosimetry in Radiation Research on Food and Agricultural
1
Products
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 of dosimetry systems is specified in ISO/ASTM Guide 51261.
1.9 This standard does not purport to address all of the
1.1 This guide covers the minimum requirements for dosim-
safety concerns, if any, associated with its use. It is the
etry and absorbed-dose validation needed to conduct research
responsibility of the user of this standard to establish appro-
on the irradiation of food and agricultural products. Such
priate safety and health practices and determine the applica-
research includes establishment of the quantitative relationship
bility of regulatory limitations prior to use.
between the absorbed dose and the relevant effects in these
products. This guide also describes the overall need for
2. Referenced Documents
dosimetry in such research, and in reporting of the results.
2.1 ASTM Standards:
1.2 This guide is intended for use by research scientists in
E 170 Terminology Relating to Radiation Measurements
the food and agricultural communities, and not just scientists
2
and Dosimetry
conducting irradiation research. It, therefore, includes more
E 177 Practice for Use of the Terms Precision and Bias in
tutorial information than most other ASTM and ISO/ASTM
3
ASTM Test Methods
dosimetry standards for radiation processing.
E 275 Practice for Describing and Measuring Performance
1.3 This guide is in no way intended to limit the flexibility
of Ultraviolet, Visible, and Near Infrared Spectrophotom-
of the experimenter in the experimental design. However, the
4
eters
radiation source and experimental set up should be chosen such
5
E 456 Terminology Relating to Quality and Statistics
that the results of the experiment will be beneficial and
E 666 Practice for Calculating Absorbed Dose from Gamma
understandable to other scientists, regulatory agencies, and the
2
or X Radiation
food and agricultural communities.
E 668 Practice for Application of Thermoluminescence Do-
1.4 The effects produced by ionizing radiation in biological
simetry (TLD) Systems for Determining Absorbed Dose in
systems depend on a large number of factors which may be
2
Radiation Hardness Testing of Electronic Devices
physical, physiological, or chemical. Although not treated in
E 925 Practice for the Periodic Calibration of Narrow Band
detail in this guide, quantitative data of environmental factors
4
Pass Spectrophotometers
that may affect the absorbed-dose response of dosimeters, such
E 958 Practice for Measuring Practical Spectral Bandwidth
as temperature and moisture content in the food or agricultural
4
of Ultraviolet Visible Spectrophotometers
products should be reported.
E 1026 Practice for Using the Fricke Reference Standard
1.5 The overall uncertainty in the absorbed-dose measure-
2
Dosimetry System
ment and the inherent absorbed-dose range within the speci-
F 1355 Guide for the Irradiation of Fresh Fruits as a
men should be taken into account in the design of an
2
Phytosanitary Treatment
experiment.
F 1356 Guide for the Irradiation of Fresh and Frozen Red
1.6 The guide covers research conducted using the follow-
Meat and Poultry to Control Pathogens and other Micro-
ing types of ionizing radiation: gamma rays, bremsstrahlung
2
organisms
X-rays, and electron beams.
F 1640 Guide for Packaging Materials for Foods to be
1.7 This guide does not include other aspects of radiation
2
Irradiated
processing research, such as planning of the experimental
F 1736 Guide for the Irradiation of Finfish and Shellfish to
design. Dosimetry must be considered as an integral part of the
2
Control Pathogens and Spoilage Microorganisms
experimental design.
2.2 ISO/ASTM Standards:
1.8 The guide does not include dosimetry for irradiator
51204 Practice for Dosimetry in Gamma Irradiation Facili-
characterization, process qualification and routine dosimetry;
2
ties for Food Processing
these subjects are described in ISO/ASTM Practices 51204,
51261 Guide for Selection and Calibration of Dosimetry
51431, 51608, 51649, and 51702. The selection and calibration
2
Systems for Radiation Processing
1
This guide is under the jurisdiction of ASTM Committee E10 on Nuclear
Technology and Applications and is the direct responsibility of Subcommittee
2
E10.01 on Dosimetry for Radiation Processing, and is also under the jurisdiction of
Annual Book of ASTM Standards, Vol 12.02.
3
ISO/TC 85/WG 3.
Annual Book of ASTM Standards, Vol 04.02.
4
Current edition approved Jan. 22, 2002. Published March 15, 2002. Originally Annual Book of ASTM Standards, Vol 03.06.
5
published as ASTM E 1900–97. Last previous ASTM edition E 1900–97. Annual Book of ASTM Standards, Vol 14.02.
© ISO/ASTM International 2002 – All rights reserved
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ISO/ASTM 51900:2002(E)
51275 Practice for Use of a Radiochromic Film Dosimetry quotient of de¯ by dm, where de¯ is the mean incremental energy
2
System imparted by ionizing radiation to matter of incremental mass
51431 Practice for Dosimetry in Electron and Bremsstrahl- dm (see ICRU 60).
2
ung Irradiation Facilities for Food Processing
de¯
2
D 5
51539 Guide for the Use of Radiation-Sensitive Indicators
dm
51540 Practice for Use of a Radiochromic Liquid Dosim-
3.1.1.1 Discussion—
2
etry System
(1) The discontinued unit for absorbed dose is the rad (1 rad =
51607 Practice for Use of the Alanine-EPR Dosimetry
100 erg/g = 0.01 Gy),
2
System
(2) Absorbed dose is sometimes referred to simply as dose,
51608 Practice for Dosimetry in an X-ray (Bremsstrahlung)
and
2
Facility for Radiation Processing
(3) For a photon source under conditions of charged particle
51649 Practice for Dosimetry in Electron Beam Facility for
equilibrium, the absorbed dose, D, may be expresssed as
Radiation Processing at Energies between 300 keV and 25
follows:
2
MeV
D5f@E~μ /r!#
en
51702 Practice for Dosimetry in a Gamma Irradiation Fa-
2
cility for Radiation Processing
where:
2
51707 Guide for Estimating Uncertainties in Dosimetry for
f = particle fluence (particles/m ),
2
Radiation Processing
E = energy of the ionizing radiation (J), and
2
2.3 International Commission on Radiation Units and
μ /r = mass energy absorption coefficient (m /kg)
en
6
Measurements (ICRU) Reports
ICRU 14 Radiation Dosimetry: X-rays and Gamma Rays
(4) If bremsstrahlung production within the specified material
with Maximum Photon Energies Between 0.6 and 50 MeV
is negligble, the mass energy absorption coefficient μ /r is
en
ICRU 17 Radiation Dosimetry: X-rays Generated at Poten-
equal to the mass energy transfer coefficient (μ /r), and
tr
tials of 5 to 150 kV
absorbed dose is equal to kerma.
ICRU 30 International Comparison of Radiological Units
˙
3.1.2 absorbed-dose rate (D)—the absorbed dose in a
and Measurements Quantitative Concepts and Dosimetry
material per incremental time interval, that is, the quotient of
in Radiobiology
dD by dt.
ICRU 34 The Dosimetry of Pulsed Radiation
dD
˙
ICRU 35 Radiation Dosimetry: Electron Beams with Ener-
D 5
dt
gies Between 1 and 50 MeV
−1
Unit: Gy · s
ICRU 60 Radiation Quantities and Units
7
3.1.2.1 Discussion—The absorbed dose rate can be speci-
2.4 NCRP Publications
fied in terms of average value of D over long-time intervals, for
NCRP Report No. 69 Dosimetry of X-Ray and Gamma-Ray
−1 −1
example, in units of Gy · min or Gy · h .
Beams for Radiation Therapy in the Energy Range 10 keV
to 50 MeV, December 1981 3.1.3 bremsstrahlung—broad-spectrum electromagnetic ra-
2.5 Methods for Calculating Absorbed Dose and Dose diation emitted when an energetic electron is influenced by
8
Distribution strong electric field, such as that in the vicinity of an atomic
ZTRAN Monte Carlo Code nucleus. Particularly, bremsstrahlung is produced when an
electron beam strikes any material (converter). The
Integrated Tiger Series (ITS) Monte Carlo Codes
bremsstrahlung spectrum depends on the electron energy, the
Energy Deposition in Multiple Layers (EDMULT) Elec-
converter material and its thickness, and contains energies up
tron Gamma Shower (EGS43)
to the maximum kinetic energy of the incident electrons.
Monte Carlo Codes
3.1.4 calibration curve—graphical representation of the
3. Terminology
dosimetry system’s response function.
3.1.5 charged particle equilibrium—a condition that exists
3.1 Definitions:
in a material under irradiation if the kinetic energies, numbers,
3.1.1 absorbed dose (D)—quantity of ionizing radiation
and direction of the secondary electrons induced by the
energy imparted per unit mass of a specified material. The SI
radiation are uniform throughout the measurement volume of
unit of absorbed dose is the gray (Gy), where 1 gray is
interest. Thus, the sum of the kinetic energies of the secondary
equivalent to the absorption of 1 joule/kg of the specified
electrons entering the volume equals the sum of the kinetic
material (1 Gy = 1 J/kg). The mathematical relationship is the
energies of the secondary electrons leaving the volume.
3.1.5.1 Discussion—Electron equilibrium often is referred
6 to as charged-particle equilibrium.
Available from the International Commission on Radiation Units and Measure-
ments, 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814 USA.
3.1.6 dosimeter—device that, when irradiated, exhibits a
7
Available from the National Council on Radiation Protection and Measure-
quantifiable change in some property of the device, which can
ments, 7910 Woodmont Ave., Bethesda, MD 20814 USA.
8
be related to absorbed dose in a given material using appro-
Available from the Radiation Shielding Information Center (RSIC) Oak Ridge
National Laboratory (ORNL) P.O. Box 2008, Oak Ridge, TN 37381 USA. priate analytical instrumentation and techniques.
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ISO/ASTM 51900:2002(E)
3.1.7 dosimeter response—the reproducible, quantifiable ra- of a measurement, that characterizes the dispersion of the
diation effect produced by a given absorbed dose. values that reasonably could be attributed to the measurand or
3.1.8 dosimetry system—a system used for determining derived quantity.
3.1.21.1 Discussion—(1) The parameter, for example, may
absorbed dose, consisting of dosimeters, measurement instru-
ments and their associated reference standards, and procedures be a standard deviation (or a given multiple of it), or the
half-width or an interval having a stated level of confidence.
for the system’s use.
(2) Uncertainty of measurement comprises, in general, many
3.1.9 electron equilibrium—charged particle equilibrium
components. Some of these components may be evaluated
for electrons.
from the statistical distribution of the results of a series of
3.1.10 equilibrium absorbed dose—the absorbed dose in a
measurements and can be characterized by experimental stan-
finite volume within the material in which the condition of
dard deviations. The other components, which also can be
approximate electron equilibrium exists.
characterized by standard deviations, are evaluated from as-
3.1.11 irradiator turntable—device used to rotate the
sumed probability distributions based on experience or other
sample during the irradiation to improve the dose uniformity
information. (3) It is understood that the result of the measure-
ratio.
ment is the best estimate of the value of the measurand, and
3.1.11.1 Discussion—Some research irradiators use turn-
that all components of uncertainty, including those arising from
tables instead of a transport or conveyor system for the purpose
systematic effects, such as components associated with correc-
of dose homogeneity improvement.
tions and reference standards, contribute to the dispersion.
3.1.12 phantom material—a mass of material with attenua-
(4) The term overall uncertainty associated witha a measurand
tion and scattering properties similar to those of the product,
should take into account all components of error.
material, or substance to be irradiated.
3.1.22 validation—establishment of documented evidence,
3.1.12.1 Discussion—Phantom material may be used during
which provides a high degree of assurance that a specified
the accelerator or irradiator characterization, or during
process will consistently produce a product meeting its prede-
absorbed-dose mapping as a substitute for the actual product,
termined specifications and quality attributes.
material or substance to be irradiated. When used in routine
3.2 Definitions of Terms Specific to This Standard:
production runs, sometimes it is referred to as compensating
3.2.1 absorbed-dose mapping—measurement of absorbed-
dummy.
dose within the irradiated specimen using dosimeters placed at
3.1.13 primary-standard dosimeter—a dosimeter of the
specified locations to produce a one-, two- or three-
highest metrological quality, established and maintained as an
dimensional distribution of absorbed dose, thus rendering a
absorbed dose standard by a national or international standards
map of absorbed-dose values.
organization (see ISO/ASTM Guide 51261).
3.2.2 dose uniformity ratio—ratio of the maximum to the
3.1.14 quality assurance—all systemic actions necessary to
minimum absorbed dose within the irradiated specimen. The
provide adequate confidence that a calibration, measurement,
concept also is referred to as the max/min dose ratio.
or process is performed to a predefined level of quality.
3.2.3 secondary radiation—electrons or photons produced
3.1.15 reference-standard dosimeter—a dosimeter of high
by the action of primary radiation on matter, such as Compton
metrological quality, used as a standard to provide measure-
recoil electrons, photoelectric electrons, and pair-production
ments traceable to, and consistent with measurements made
electrons.
using primary–standard dosimeters.
3.2.4 target dose—absorbed dose delivered to a specific
3.1.16 response function—mathematical representation of
location in, or on the specimen that results in an acceptable
the relationship between dosimeter response and absorbed dose
absorbed-dose distribution within the rest of the specimen.
for a given dosimetry system.
3.2.5 transit dose—absorbed dose delivered to product,
3.1.17 routine dosimeter—dosimeter calibrated against a
material, or substance as it moves from the load/unload
primary-, reference-, or transfer-standard dosimeter and used
position to the irradiate position, and back to the load/unload
for routine absorbed-dose measurement (see ISO/ASTM Guide
position.
51261).
4. Significance and Use
3.1.18 simulated product—a mass of material with attenu-
ation and scattering properties similar to those of the product,
4.1 This guide is intended to provide direction on the
material or substance to be irradiated.
dosimetry aspects of experiments in food and agricultural
3.1.19 traceability—the documentation demonstrating by
research. Research concerning the effectiveness of irradiation
means of an unbroken chain of comparisons that a measure-
of food and agricultural products to achieve a defined benefit
ment is in agreement within acceptable limits of uncertainty
necessarily involves very different operating parameters from
with comparable nationally- or internationally-recognized
one study to another. For example, the absorbed dose required
standards.
to sterilize fruit flies is much lower than the doses required to
3.1.20 transfer-standard dosimeter—a dosimeter often a
inactivate some bacterial pathogens in meat, or to decontami-
reference–standard dosimeter suitable for transport between
nate spices. Furthermore, the kind and design of the facility,
different locations, used to compare absorbed-dose measure-
including type of radiation source that may be used in these
ments (see ISO/ASTM Guide 51261).
studies are often very different. Yet the investigators must
3.1.21 uncertainty—a parameter associated with the result
report to the scientific community sufficient information to
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ISO/ASTM 51900:2002(E)
characterize adequately their studies so that these studies can form of electrons or bremsstrahlung X-rays. For this type of
be repeated by another competent researcher, and so that the accelerator, radiation is emitted or generated and directed at the
absorbed dose may be reproduced properly during the conduct specimen placed beneath a collimator. The collimator is used to
of the experiment. create a highly defined beam of radiation.
4.2 Ideally, an experiment should be designed to irradiate 5.3.1 For an electron accelerator system, the principle sys-
the specimen uniformly. In practice, a certain variation in tem parameters affecting absorbed dose are the energy spec-
absorbed dose through the specimen will exist. Absorbed-dose trum, average beam current, beam dispersion, and conveyor
mapping should determine the magnitude, location, and repro- speed (where applicable). The electron energy spectrum dic-
ducibility of the maximum (D ) and minimum absorbed dose tates the variation of absorbed dose with depth in a given
max
(D ) for a given set of experimental parameters. When material (see ISO/ASTM Practices 51431, 51608, and 51649).
min
pronounced absorbed-dose gradients exist, it is important to 5.3.2 A bremsstrahlung X-ray accelerator emits short-
use dosimeters that are suitable for measuring these variations. wavelength electromagnetic radiation, similar in energy to
For example, very small dosimeters may be needed to measure nuclear gamma radiation. Although their effects on materials
the change in absorbed dose across the interface between generally are similar, these kinds of radiation differ in their
materials. energy spectra, angular distributions, depth-dose distributions
4.3 Theoretical calculations may provide useful information and absorbed-dose rates (see ISO/ASTM Practices 51431,
about absorbed-dose distribution in the irradiated specimen, 51608, and 51649). Spectrum filtration can be used to reduce
especially near material interfaces (see Methods for Calcula- the low-energy component of the radiation, thus improving the
8
tion in Absorbed Dose and Dose Distribution and Refs (1) and dose uniformity ratio in the specimen.
9
(2). 5.3.3 Specimens may be irradiated using a self-contained
4.4 Proper reporting of the experimental set-up is important bremsstrahlung X-ray irradiator. The x-rays are produced in a
since the degree of biological effect may be a function of conventional manner, but the unit is totally self-contained.
various factors such as the absorbed-dose rate, energy of the Spectrum filtration can be used to reduce the low-energy
incident radiation and the type of incident radiation. For component of the radiation, thus improving the dose unifor-
example, the total absorbed dose received by a specimen may mity ratio in the specimen. In some cases, irradiator turntables
be the same for two different applications, but the effect of the are used.
irradiations on the food or agricultural products may be 5.4 Radiation Processing Facilities—Commercial radiation
different because the absorbed-dose rates were different. processing facilities also can be used for conducting research
4.5 Factors that may alter the response of agricultural on food and agricultural products (see ISO/ASTM Practices
products to ionizing radiation include genus, species, variety, 51204 and 51431). These facilities can be categorized by
vigor, life-stage, initial quality, state of ripeness, temperature, irradiator type (for example, container or bulk flow), conveyor
moisture content, pH, packaging, shipping and storage time, system (for example, shuffle-dwell or continuous), and operat-
and conditions. Although these factors are not discussed ing mode (for example, batch or continuous).
elsewhere in this guide, they should be considered in the
6. Radiation Source Characteristics
experimental design (see ASTM Guides F 1355, F 1356, and F
6.1 The gamma-ray sources used in a facility considered in
1736).
60
this guide consist of sealed elements (usually of Co
137
5. Types of Facilities and Modes of Operation
or Cs), which are typically linear rods or pencils arranged
singly, or in one or more planar or cylindrical arrays.
5.1 This guide covers the following types of radiation
6.1.1 Cobalt-60 emits photons with energies of approxi-
sources and modes of operation, which may be used to irradiate
mately 1.17 and 1.33 MeV in nearly equal proportions.
food and agricultural products for the purpose of conducting
Cesium-137 produces photons with energies of approximately
research.
0.662 MeV (3, 4).
5.2 Self Contained Research Irradiators—Self-contained,
6.1.2 For gamma-ray sources, the only variation in the
dry-storage research irradiators are devices that house the
137 60
source output is the known reduction in the activity caused by
radiation source (usually Cs or Co) in a protective lead
radioactive decay. The reduction in the source strength, and the
shield (or other high atomic number material), and may have a
corresponding increase in the irradiation time, may be calcu-
mechanism to rotate or lower the specimen from the load/
lated or obtained from source-decay tables.
unload position to the irradiate position. The most common
60 137
6.1.3 The half-lives for Co and Cs are approximately
method of use is to rotate the specimen on an irradiator
5.27 years and 30.2 years, respectively (3).
turntable in front of the source. The second method is to
distribute the source in a circular array. The irradiated speci-
NOTE 1—Although the output of gamma-ray sources may be expected
men is located at the center of the array, resulting in a uniform
to be constant (except for radioactive decay), errors may be introduced by
134
dose distribution.
the existence of radioactive impurities (for example, Cs radioactive
137
impurities in Cs).
5.3 Electron Accelerator (Electron and Bremsstrahlung
X-ray Modes—Accelerator-generated radiation can be in the
6.2 Direct-action electron accelerators, which employ dc or
pulsed high-voltage generators can produce electron energies
9 up to 5 MeV. Indirect-action electron accelerators use micro-
The boldface numbers in parentheses refer to the bibliography at the end of this
standard. wave or very high frequency (vhf) ac power to produce
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ISO/ASTM 51900:2002(E)
electron energies typically from 5 MeV to 15 MeV. 7.4.1 Prior to use, dosimetry systems shall be calibrated in
6.3 The continuous energy spectrum of the bremsstrahlung accordance with the user’s documented procedure that speci-
X-rays varies from almost zero up to the maximum energy of fies details of the calibration process and quality assurance
the electrons incident on the converter (See Reference (5) and requirements. This calibration procedure shall be repeated at
ISO/ASTM Practice 51608). regular intervals to ensure that the accuracy of the absorbed
dose measurement is maintained within required limits. Irra-
NOTE 2—Spectrum filtration often is used to eliminate the low-energy
diation is a critical component of the calibration of the
component of the radiation field.
dosimetry system. Detailed calibration procedures are provided
6.4 For food and agricultural products, regulations in some
in ISO/ASTM Guide 51261.
countries limit the maximum electron energy to 10 MeV and
7.4.2 Calib
...