ISO/ASTM 51940:2004

Guide for dosimetry for sterile insects release programs

ISO/ASTM 51940:2004 outlines dosimetric procedures to be followed for the radiation sterilization of live insects for use in pest management programs. The procedures outlined in ISO/ASTM 51940:2004 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 ISO/ASTM 51940:2004. ISO/ASTM 51940:2004 covers dosimetry in the irradiation of insects for these types of irradiators: self-contained dry-storage 137Cs or 60Co irradiators, large-scale gamma irradiators, and electron accelerators. The absorbed dose for insect sterilization is typically within the range of 20 Gy to 600 Gy. ISO/ASTM 51940:2004 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. ISO/ASTM 51940:2004 also covers the use of radiation-sensitive indicators for the visual and qualitative indication that the insects have been irradiated. ISO/ASTM 51940:2004 does not purport to address all of the safety concerns, if any, associated with its use.

Guide de la dosimétrie pour des programmes de lâchers d'insectes stériles

General Information

• Status: Withdrawn
• Publication Date: 24-Oct-2004
• Withdrawal Date: 24-Oct-2004
• 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
• Completion Date: 22-Mar-2013

Relations

• Revised: ISO/ASTM 51940:2013 - Guide for dosimetry for sterile insects release programs
• Effective Date: 03-Dec-2011
• Revises: ISO/ASTM 51940:2002 - Guide for dosimetry for irradiation of insects for sterile release programs
• Effective Date: 15-Apr-2008

Standards Content (Sample)

INTERNATIONAL ISO/ASTM
STANDARD 51940
Second edition
2004-08-15
Guide for dosimetry for sterile insect
release programs
Guide de la dosimétrie pour des programmes de lâchers
d’insectes stériles
Reference number
ISO/ASTM 51940:2004(E)
© ISO/ASTM International 2004

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ISO/ASTM 51940:2004(E)
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ii © ISO/ASTM International 2004 – All rights reserved

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ISO/ASTM 51940:2004(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 Installation qualification . 5
9 Operational qualification . 6
10 Performance qualification . 7
11 Routine product processing . 8
12 Measurement uncertainty . 9
13 Keywords . 9
Annexes . 9
Bibliography . 11
Table A2.1 Recommended procedures . 11
© ISO/ASTM International 2004 – All rights reserved iii

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ISO/ASTM 51940:2004(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 project between ISO and ASTM International has been formed to develop and maintain a group of
ISO/ASTM radiation processing dosimetry standards. Under this 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 document 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 51940 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 2004 – All rights reserved

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ISO/ASTM 51940:2004(E)
Standard Guide for
1
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.
1. Scope 1.5 This guide also covers the use of radiation-sensitive
indicators for the visual and qualitative indication that the
1.1 This guide outlines dosimetric procedures to be fol-
insects have been irradiated.
lowed for the radiation sterilization of live insects for use in
1.6 This standard does not purport to address all of the
pest management programs. The primary use of irradiated,
safety concerns, if any, associated with its use. It is the
reproductively sterile insects is in the Sterile Insect Technique,
responsibility of the user of this standard to establish appro-
where large numbers of sterile insects are released into the field
priate safety and health practices and determine the applica-
to mate with and thus control pest populations of the same
bility of regulatory limitations prior to use.
species. A secondary use of sterile insects is as benign hosts for
rearing insect parasitoids. The procedures outlined in this guide
2. Referenced documents
will help ensure that insects processed with ionizing radiation
2
2.1 ASTM Standards:
from gamma, electron, or X-ray sources receive absorbed
E 170 Terminology Relating to Radiation Measurements
doses within a predetermined range. Information on effective
and Dosimetry
dose ranges for specific applications of insect sterilization, or
E 668 Practice for Application of Thermoluminescence-
on methodology for determining effective dose ranges, is not
Dosimetry (TLD) Systems for Determining Absorbed Dose
within the scope of this guide.
in Radiation-Hardness Testing of Electronic Devices
NOTE 1—Dosimetry is only one component of a total quality control
E 1026 Practice for Using the Fricke Reference Standard
program to ensure that irradiated insects are adequately sterilized and
Dosimetry System
sufficiently competitive or otherwise suitable for their intended purpose.
E 2116 Practice for Dosimetry for a Self-Contained
1.2 This guide covers dosimetry in the irradiation of insects
Gamma-Ray Irradiator
137
for these types of irradiators: self-contained dry-storage Cs
E 2303 Guide for Absorbed-Dose Mapping in Radiation
60
or Co irradiators, large-scale gamma irradiators, and electron
Processing Facilities
accelerators. Additional, detailed information on dosimetric
E 2304 Practice for Use of a LiF Photo-Fluorescent Film
procedures to be followed in installation qualification, opera-
Dosimetry System
2
tional qualification, performance qualification, and routine
2.2 ISO/ASTM Standards:
product processing can be found in ISO/ASTM Practices
51261 Guide for Selection and Calibration of Dosimetry
51608 (X-ray [bremsstrahlung] facilities), 51649 (electron
Systems for Radiation Processing
beam facilities), 51702 (large-scale gamma facilities), and
51275 Practice for Use of a Radiochromic Film Dosimetry
ASTM Practice E 2116 (self-contained dry-storage gamma
System
facilities).
51400 Practice for Characterization and Performance of a
1.3 The absorbed dose for insect sterilization is typically
High-Dose Radiation Dosimetry Calibration Laboratory
within the range of 20 Gy to 600 Gy.
51538 Practice for Use of the Ethanol-Chlorobenzene Do-
1.4 This guide refers, throughout the text, specifically to
simetry System
reproductive sterilization of insects. It is equally applicable to
51539 Guide for the Use of Radiation-Sensitive Indicators
radiation sterilization of invertebrates from other taxa (for
51540 Practice for Use of a Radiochromic Liquid Dosim-
example, Acarina, Gastropoda) and to irradiation of live insects
etry System
or other invertebrates for other purposes (for example, induc-
51607 Practice for Use of the Alanine-EPR Dosimetry
ing mutations), provided the absorbed dose is within the range
System
specified in 1.3.
51608 Practice for Dosimetry in an X-Ray (Bremsstrahl-
ung) Facility for Radiation Processing
51649 Practice for Dosimetry in an Electron Beam Facility
1
This guide is under the jurisdiction of ASTM Committee E10 on Nuclear
for Radiation Processing at Energies Between 300 keV
Technology and Applications and is the direct responsibility of Subcommittee
and 25 MeV
E10.01 on Dosimetry for Radiation Processing, and is also under the jurisdiction of
ISO/TC 85/WG 3.
Current edition approved June 30, 2004. Published August 15, 2004. Originally
2
published as ASTM E 1940–98. Last previous ASTM edition E 1940–98. The For referenced ASTMand ISO/ASTM standards, visit the ASTM website,
present International Standard ISO/ASTM 51940:2004(E) replaces ASTM E www.astm.org, or contact ASTM Customer Service at [e-mail]. For
1940–98 and is a major revision of the last previous edition ISO/ASTM Annual Book of ASTM Standards volume information, refer to the standard’s
51940:2002(E). Document Summary page on the ASTM website.
© ISO/ASTM International 2004 – All rights reserved
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ISO/ASTM 51940:2004(E)
51702 Practice for Dosimetry in a Gamma Irradiation Fa- 3.1.2 absorbed-dose mapping—measurement of absorbed-
cility for Radiation Processing dose within process load using dosimeters placed at specified
51707 Guide for Estimating Uncertainties in Dosimetry for locations to produce a one-, two- or three-dimensional distri-
Radiation Processing bution of absorbed dose, thus rendering a map of absorbed-
51956 Practice for Use of Thermoluminescence-Dosimetry dose values.
˙
(TLD) Systems for Radiation Processing
3.1.3 absorbed-dose rate, D—absorbed dose in a material
2.3 International Commission on Radiation Units and
per incremental time interval, that is, the quotient of dD by dt
3
Measurements (ICRU) Reports:
(see ICRU 60).
ICRU 14 Radiation Dosimetry: X-rays and Gamma Rays
˙
D 5 dD/dt
with Maximum Photon Energies Between 0.6 and 50 MeV
−1
SI Unit: Gy·s
ICRU 17 Radiation Dosimetry: X-rays Generated at Poten-
3.1.3.1 Discussion—The absorbed-dose rate can be speci-
tials of 5 to 150 kV
˙
ICRU 34 The Dosimetry of Pulsed Radiation fied in terms of average value of D over long-time intervals, for
−1 −1
ICRU 35 Radiation Dosimetry: Electron Beams with Ener- example, in units of Gy·min or Gy·h .
gies Between 1 and 50 MeV 3.1.4 calibration—process whereby the response of a mea-
ICRU 60 Fundamental Quantities and Units for Ionizing suring system or measuring instrument is characterized through
Radiation comparison with an appropriate standard that is traceable to,
4
2.4 NCRP Publications: and consistent with, a national standard.
NCRP Report No. 69, Dosimetry of X-Ray and Gamma- 3.1.5 canister—durable, reusable container, usually an alu-
Ray Beams for Radiation Therapy in the Energy Range 10 minum or steel cylinder, used to house a product (for example,
keV to 50 MeV, December 1981 factory-reared insects in packaging containers) during the
radiation process.
3. Terminology
3.1.5.1 Discussion—Canisters are not used in some appli-
3.1 Definitions:
cations in which the packaging container is sufficiently rigid
3.1.1 absorbed dose (D)—quantity of ionizing radiation
and the design of the irradiator is appropriate.
energy imparted per unit mass of a specified material. The SI
3.1.6 dose uniformity ratio—ratio of maximum to minimum
unit of absorbed dose is the gray (Gy), where 1 gray is
absorbed dose within the process load. The concept is also
equivalent to the absorption of 1 joule per kilogram of the
referred to as the max/min dose ratio.
specified material (1 Gy = 1 J/kg). The mathematical relation-
3.1.7 dosimeter—device that, when irradiated, exhibits a
ship is the quotient of de¯ by dm, where de¯ is the mean
quantifiable change in some property of the device which can
incremental energy imparted by ionizing radiation to matter of
be related to absorbed dose in a given material using appro-
incremental mass dm (see ICRU 60).
priate analytical instrumentation and techniques.
3.1.8 dosimeter set—one or more dosimeters used to mea-
D 5 de¯/dm
sure the absorbed dose at a location and whose average reading
3.1.1.1 Discussion—The discontinued unit for absorbed
is used to determine absorbed dose at that location.
dose is the rad (1 rad = 100 erg/g = 0.01 Gy). Absorbed dose
3.1.9 dosimetry system—system used for determining ab-
is sometimes referred to simply as dose. For a photon source
sorbed dose, consisting of dosimeters, measurement instru-
under conditions of charged particle equilibrium, the absorbed
ments and their associated reference standards, and procedures
dose, D, may be expressed as follows:
for the system’s use.
D5F Eμ /r
en
3.1.10 factory-reared insects—insects that are reared in
large quantity in a laboratory or factory setting for use,
where:
2
following reproductive sterilization through irradiation, as live
F = particle fluence (particles/m ),
animals in pest management programs.
E = energy of the ionizing radiation (J), and
2
3.1.11 installation qualification—obtaining and document-
μ /r = mass energy absorption coefficient (m /kg).
en
ing evidence that the irradiator, with all its associated equip-
If bremsstrahlung production within the specified material is
ment and instrumentation, has been provided and installed in
negligible, the mass energy absorption coefficient (μ /r)is
en
accordance with specifications.
equal to the mass energy transfer coefficient (μ /r), and
tr
3.1.12 irradiator turntable—device used to rotate the can-
absorbed dose is equal to kerma if, in addition, charged particle
ister during the radiation process so as to improve dose
equilibrium exists.
uniformity.
3.1.12.1 Discussion—An irradiator turntable is often re-
3
Available from the International Commission on Radiation Units and Measure-
ferred to as a turntable. Some irradiator geometries, for
ments, 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814, USA.
4
example, with an annular array of radiation sources surround-
Available from the National Council on Radiation Protection and Measure-
ments, 7910 Woodmont Ave., Bethesda, MD 20814, USA. ing the product, may not need a turntable.
© ISO/ASTM International 2004 – All rights reserved
2

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ISO/ASTM 51940:2004(E)
3.1.13 measurement quality assurance plan—documented 3.1.23 traceability—see measurement traceability.
program for the measurement process that ensures, on a 3.1.24 transfer-standard dosimeter—dosimeter, often a
continuing basis, that the overall uncertainty meets the require- reference-standard dosimeter, suitable for transport between
ments of the specific application. This plan requires traceability different locations, used to compare absorbed-dose measure-
to, and consistency with, nationally or internationally recog- ments (see ISO/ASTM Guide 51261).
nized standards. 3.1.25 transit dose—absorbed dose delivered to irradiated
3.1.14 measurement traceability—ability to demonstrate by samples while the item to be irradiated in a fixed or turntable
position moves into and out of that position or while the
means of an unbroken chain of comparisons that a measure-
movable source moves into and out of its irradiation position.
ment is in agreement within acceptable limits of uncertainty
3.2 Definitions of other terms used in this standard that
with comparable nationally or internationally recognized stan-
pertain to radiation measurement and dosimetry may be found
dards.
in ASTM Terminology E 170. Definitions in E 170 are com-
3.1.15 operational qualification—obtaining and document-
patible with ICRU 60; that document, therefore, may be used
ing evidence that installed equipment and instrumentation
as an alternative reference.
operate within predetermined limits when used in accordance
with operational procedures.
4. Significance and use
3.1.16 packaging container—container such as a paper cup
4.1 The major use of factory-reared insects is in sterile
with lid, plastic bag, or plastic bottle that is used to hold
release programs (for example, Sterile Insect Technique, or
factory-reared insects during irradiation and, typically, during
5
SIT) for suppressing or eradicating pest populations (1) . Large
subsequent shipment from the irradiation facility to the release
numbers of reproductively sterile (irradiated) insects are re-
site.
leased into an area where a wild “target population” of the
3.1.17 performance qualification—obtaining and docu-
same species exists. The wild population is reduced to the
menting evidence that the equipment and instrumentation, as
extent that the sterile males are successful in mating with wild
installed and operated in accordance with operation proce-
females. The radiation dose to the factory-reared insects should
dures, consistently perform according to predetermined criteria
be within a range that induces the desired level of sterility
and thereby yield product that meets specifications.
without substantially reducing the ability of factory-reared
3.1.18 process load—volume of material with a specified
males to compete with wild males for mates. Species targeted
product loading configuration irradiated as a single entity.
by SIT programs are typically major pests affecting agriculture
3.1.19 radiation-sensitive indicator—material such as a
or human health, so the assurance by standardized dosimetry
coated or impregnated adhesive-back (or adhesive-front) sub-
that insects have been properly irradiated is of crucial impor-
strate, ink, or coating which may be affixed to or printed on the
tance to agriculture growers, agricultural regulators, public
irradiated sample and which undergoes a visual change when
health officials, and the public (1-4). The irradiator operator
exposed to ionizing radiation (see ISO/ASTM Guide 51539).
must demonstrate by means of accurate absorbed-dose mea-
3.1.19.1 Discussion—Radiation-sensitive indicators are of-
surements that all insects will receive absorbed dose within the
ten referred to as “indicators.” Indicators may be used to show
specified range.
that products have been exposed to ionizing radiation. They
4.2 Another use of factory-reared insects is in the produc-
can be used to provide a visual and qualitative indication of
tion of parasitoids for release against populations of insect
radiation exposure and can be used to distinguish between
pests (5). Parasitoids are insects that spend the larval stage
irradiated and unirradiated samples. Indicators cannot be used
feeding within the body of a “host” species, typically killing
as a substitute for proper dosimetry.
the host. In some parasitoid programs, factory-reared host
3.1.20 reference-standard dosimeter—dosimeter of high
insects are irradiated before being offered to parasitoids. This
metrological quality, used as a standard to provide measure-
eliminates the need to separate unparasitized hosts from
ments traceable to and consistent with measurements made
parasitoids so that fertile, unparasitized host insects are not
with primary-standard dosimeters (see ISO/ASTM Guide
inadvertently released into the field.
51261).
4.3 Factory-reared insects may be treated with ionizing
3.1.21 routine dosimeter—dosimeter calibrated against a 137 60
radiation, such as gamma radiation from Cs or Co sources,
primary-, reference-, or transfer-standard dosimeter and used
or X-rays or electrons from accelerators. Gamma irradiation of
for routine absorbed-dose measurement (see ISO/ASTM Guide
insects is usually carried out in small, fixed-geometry, dry-
51261).
storage irradiators (6-8). Dosimetry methods for gamma irra-
3.1.22 simulated product—material with attenuation and
diation of insects have been demonstrated and include useful
scattering properties similar to those of the product, material or
procedures for mapping the absorbed dose throughout the
substance to be irradiated.
volume of the insect canister in these small irradiators (ASTM
3.1.22.1 Discussion—Simulated product is used during ir-
Practice E 2116 and Ref (9)) as well as large-scale gamma
radiator characterization as a substitute for the actual product,
irradiators (ISO/ASTM Practice 51702 and Ref (10)).
material, or substance to be irradiated. When used in routine
production runs, it is sometimes referred to as compensating
5
dummy. When used for absorbed-dose mapping, simulated
The boldface numbers in parentheses refer to the bibliography at the end of this
product is sometimes referred to as a phantom material. standard.
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ISO/ASTM 51940:2004(E)
4.4 Specifications for irradiation of factory-reared insects 5.3.1 Typically, accelerators produce a narrow electron
include a lower limit of absorbed dose and may include a beam that is diffused to cover the length and width of a target
central target dose and an upper limit. These values are based area, which may be the location where samples are irradiated
on program requirements and on scientific data on effects of (see 5.3.3) or an X-ray target (see 5.3.2). Diffusion may be
absorbed dose on the sterility, viability, and competitiveness of accomplished using a magnetic scanner (to sweep the beam
the factory-reared insects. back and forth rapidly), magnetic defocusing lens, or scattering
4.5 For each irradiator, absorbed-dose rate at a reference foils.
position within the irradiated volume of insects or simulated
5.3.2 X-rays (bremsstrahlung) are produced by striking an
product is measured using a transfer- or reference-standard
X-ray target with an electron beam. The target is made of
dosimetry system. That measurement may be used to calculate
tungsten, tantalum, or other metal with a high atomic number,
the timer setting, conveyor speed, or other parameter required
high melting temperature, and high thermal conductivity.
to deliver the specified absorbed dose to the insects.
NOTE 2—Insects could be irradiated using a self-contained portable
4.6 Absorbed-dose mapping for establishing magnitudes
X-ray irradiator. The X-rays (bremsstrahlung) are produced in a conven-
and locations of D and D is performed using actual
min max
tional manner, but the unit is totally self-contained (requiring no additional
product or simulated product (9).
shielding).
4.7 Dosimetry is part of a measurement quality assurance
5.3.3 For processing, samples are typically carried on a
plan that is applied to ensure that the radiation process meets
moving conveyor through the electron or X-ray beam. Because
predetermined specifications (11).
of the narrow angular distribution of the radiation, use of
5. Types of facilities and modes of operation
continuously moving conveyors (rather than static-irradiation
or shuffle-dwell systems) enhances dose uniformity.
5.1 Self-Contained Dry-Source Irradiators (see Ref (12))—
Most insect sterilization is accomplished by using gamma 5.3.4 Additional information on electron accelerator facili-
137 60
ties and modes of operation may be found in ISO/ASTM
radiation from either Cs or Co self-contained irradiators.
Practices 51649 (electron beam) and 51608 (X-ray).
These devices house the radiation source in a protective shield
of lead (or other appropriate high atomic number material), and
usually have a mechanism to rotate or lower the canister from 6. Radiation source characteristics
the load position to the irradiation position.
6.1 Gamma Irradiators:
5.1.1 A common method is to distribute the source in an
6.1.1 The radiation source used in the gamma facilities
annular array. During irradiation, the sample of factory-reared 60
considered in this guide consists of sealed elements of Co
insects is located at the center of the array, where the 137
or Cs which are typically linear rods or “pencils” arranged
absorbed-dose distribution is relatively uniform. In this design,
in one or more planar or cylindrical arrays.
an irradiator turntable would not normally be necessary.
6.1.2 Cobalt-60 emits photons with energies of approxi-
5.1.2 A second method is to rotate the canister holding the
mately 1.17 and 1.33 MeV in nearly equal proportions (13).
insects on an irradiator turntable within the radiation field to
Cesium-137 emits photons with energies of approximately
achieve a more uniform dose distribution within the process
0.662 MeV (13).
load. The axis of rotation should be parallel to the source
60 137
6.1.3 The half-lives for Co and Cs are 5.2708 years
pencils (see 6.1.1), which are generally vertical.
(14) and 30.07 years (15), respectively.
5.2 Large-Scale Gamma Irradiators—Gamma irradiation
6.1.4 For gamma-radiation sources, the only variation in the
of insects is also carried out in large-scale irradiators, either
source output is the known reduction in the activity caused by
pool-type or dry-storage. In these facilities, the source typically
60 radioactive decay. The reduction in the source strength, and the
consists of a series of rods (pencils) that contain Co and can
required increase in the irradiation time, may be calculated (see
be raised or lowered into a large irradiation room. When
9.3.4) or obtained from tables provided by the irradiator
retracted from the irradiation room, the source is shielded by
manufacturer.
water (pool-type), or lead or other appropriate high atomic
6.2 Electron Accelerator (Electron and X-ray Modes):
number material (dry-storage), or both.
6.2.1 For an electron accelerator, the two principal beam
5.2.1 Continuous Operation—A common method of use is
characteristics are the energy spectrum and the average beam
for samples of insects to be carried on a conveyor in one or
current. The electron energy spectrum affects the variation of
more revolutions around a central source, resulting in a
absorbed dose with depth in a given material, and the average
relatively uniform absorbed-dose distribution. The source is
beam current affects the absorbed-dose rate.
retracted from the irradiation room only when the irradiator is
6.2.1.1 Direct-action electron accelerators employ dc or
not in use.
pulsed high-voltage generators typically produce electron en-
5.2.2 Batch Operation—An alternative method of use is to
ergies up to 5 MeV.
place canister(s) of insects into the irradiation room while the
6.2.1.2 Indirect-action electron accelerators use microwave
source is shielded, and then raise or lower the source into the
or very high frequency (VHF) ac power to produce electron
chamber for the length of time required to achieve the desired
energies typically from 5 MeV to 15 MeV.
absorbed dose.
5.3 Electron Accelerator—Accelerator-generated radiation 6.2.2 For an X-ray (bremsstrahlung) facility, besides beam
characteristics noted in 6.2.1, X-ray target design is a critical
is in the form of electrons or X-rays (bremsstrahlung).
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ISO/ASTM 51940:2004(E)
parameter. X-rays are similar to gamma radiation from radio- 7.2 Calibration of Dosimetry Systems:
active isotopic sources. Although their effects on materials are 7.2.1 Prior to use, the dosimetry system (consisting of a
generally similar, these kinds of radiation differ in their energy specific batch of dosimeters and specific measurement instru-
spectra, angular distributions, and absorbed-dose rates. The ments) shall be calibrated in accordance
...