ISO/ASTM 51607:2002
(Main)Practice for use of the alanine-EPR dosimetriy system
Practice for use of the alanine-EPR dosimetriy system
ISO/ASTM 51607 covers materials description, dosimeter preparation, instrumentation and procedures for using the alanine-EPR dosimetry system for measuring the absorbed dose in materials irradiated with photons and electrons. The system is based on electron paramagnetic resonance (EPR) spectroscopy of free radicals derived from the amino acid alanine. It is classified as a reference standard dosimetry system. This International Standard covers alanine-EPR dosimetry systems for dose measurements under the following conditions: the absorbed dose range is between 1 Gy and 105 Gy; the absorbed dose rate is up to 102 Gy s -1 for continuous radiation fields and up to 5 times 107 Gy s-1 for pulsed radiation fields; the radiation energy for photons and electrons is between 0,1 MeV and 28 MeV; the irradiation temperature is between - 60 °C and + 90 °C.
Pratique de l'utilisation d'un système dosimétrique à l'alanine utilisant la résonance paramagnétique électronique
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INTERNATIONAL ISO/ASTM
STANDARD 51607
First edition
2002-03-15
Practice for use of the alanine-EPR
dosimetry system
Pratique de l’utilisation d’un système dosimétrique à l’alanine
utilisant la résonance paramagnétique électronique
Reference number
ISO/ASTM 51607:2002(E)
© ISO/ASTM International 2002
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ISO/ASTM 51607:2002(E)
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ii © ISO/ASTM International 2002 – All rights reserved
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ISO/ASTM 51607:2002(E)
Contents Page
1 Scope . 1
2 Referenced documents . 1
3 Terminology . 1
4 Significance and use . 2
5 Dosimeter material . 2
6 Preparation of dosimeters . 2
7 Apparatus . 3
8 Calibration procedures . 3
9 Measurement of the epr spectrum . 4
10 General practice . 4
11 Environmental interferences . 5
12 Minimum documentation requirements . 5
13 Measurement uncertainty . 5
14 Keywords . 5
Annexes . 6
Bibliography . 6
Figure 1 EPR spectrum of an alanine dosimeter irradiated to an absorbed dose of 1 kGy . 4
© ISO/ASTM International 2002 – All rights reserved iii
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ISO/ASTM 51607:2002(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 51607 was developed by ASTM Committee E10, Nuclear Technology and
Applications, through Subcommittee E10.01, and by Technical Committee ISO/TC 85, Nuclear Energy.
Annexes A1 and A2 of this International Standard are for information only.
iv © ISO/ASTM International 2002 – All rights reserved
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ISO/ASTM 51607:2002(E)
Standard Practice for
1
Use of the Alanine-EPR Dosimetry System
This standard is issued under the fixed designation ISO/ASTM 51607; the number immediately following the designation indicates the
year of original adoption or, in the case of revision, the year of last revision.
4
1. Scope in Radiation-Hardness Testing of Electronic Devices
2.2 ISO/ASTM Standards:
1.1 This practice covers materials description, dosimeter
51204 Practice for Dosimetry in Gamma Irradiation Facili-
preparation, instrumentation, and procedures for using the
4
ties for Food Processing
alanine-EPR dosimetry system for measuring the absorbed
51261 Guide for Selection and Calibration of Dosimetry
dose in materials irradiated with photons and electrons. The
4
Systems for Radiation Processing
system is based on electron paramagnetic resonance (EPR)
51400 Practice for Characterization and Performance of a
spectroscopy of free radicals derived from the amino acid
2
High-Dose Gamma Radiation Dosimetry Calibration
alanine. It is classified as a reference standard dosimetry
4
Laboratory
system (see ISO/ASTM Guide 51261).
51431 Practice for Dosimetry in Electron and Bremsstrahl-
1.2 This practice covers alanine-EPR dosimetry systems for
4
ung Irradiation Facilities for Food Processing
dose measurements under the following conditions:
5
51707 Guide for Estimating Uncertainties in Dosimetry for
1.2.1 The absorbed dose range is between 1 and 10 Gy.
4
2 −1
Radiation Processing
1.2.2 The absorbed dose rate is up to 10 Gy s for
6
7 −1
2.3 ICRU Reports:
continuous radiation fields and up to 5 3 10 Gy s for pulsed
3
ICRU Report 14 Radiation Dosimetry: X-Rays and
radiation fields (1-3).
Gamma-Rays with Maximum Photon Energies Between
1.2.3 The radiation energy for photons and electrons is
0.6 and 50 MeV
between 0.1 and 28 MeV (1, 2, 4).
ICRU Report 17 Radiation Dosimetry: X-Rays Generated at
1.2.4 The irradiation temperature is between − 60
Potentials of 5 to 150 kV
and + 90°C (2, 5).
ICRU Report 34 The Dosimetry of Pulsed Radiation
1.3 The values stated in SI units are to be regarded as the
ICRU Report 35 Radiation Dosimetry: Electron Beams with
standard. The values given in parentheses are for information
Energies between 1 and 50 MeV
only.
ICRU Report 37 Stopping Powers for Electrons and
1.4 This standard does not purport to address all of the
Positrons
safety concerns, if any, associated with its use. It is the
ICRU Report 44 Tissue Substitutes in Radiation Dosimetry
responsibility of the user of this standard to establish appro-
and Measurement
priate safety and health practices and determine the applica-
ICRU Report 60 Radiation Quantities and Units
bility of regulatory limitations prior to use.
2.4 ISO Document:
7
2. Referenced Documents
Guide for the Expression of Uncertainty in Measurements
2.1 ASTM Standards:
3. Terminology
E 170 Terminology Relating to Radiation Measurements
4
3.1 Definitions—Appropriate terms may be found in ASTM
and Dosimetry
5
Terminology E 170.
E 178 Practice for Dealing with Outlying Observations
5
3.2 Definitions of Terms Specific to This Standard:
E 456 Terminology Relating to Quality and Statistics
3.2.1 alanine dosimeter—a specified quantity and physical
E 668 Practice for Application of Thermoluminescence-
form of the radiation-sensitive material alanine and any added
Dosimetry (TLD) Systems for Determining Absorbed Dose
inert substance such as a binder.
3.2.2 alanine-EPR dosimetry system—a system used for
1
This practice is under the jurisdiction of ASTM Committee E10 on Nuclear
determining absorbed dose, consisting of the alanine dosim-
Technology and Applications and is the direct responsibility of Subcommittee
E10.01on Dosimetry for Radiation Processing, and is also under the jurisdiction of eters, an EPR spectrometer, the calibration curve, reference
ISO/TC 85/WG 3.
standards, and procedures for the system’s use.
Current edition approved Jan. 22, 2002. Published March 15, 2002. Originally
3.2.3 EPR spectroscopy—the measurement of resonant ab-
e1
published as ASTM E 1607 – 94. Last previous ASTM edition E 1607 – 96 .
sorption of electromagnetic energy resulting from the transition
ASTM E 1607 – 94 was adopted by ISO in 1998 with the intermediate designation
ISO 15566:1998(E). The present International Standard ISO/ASTM 51607:2002(E)
of unpaired electrons between different energy levels, upon
is a revision of ISO 15566.
2
The term “electron spin resonance” (ESR) is used interchangeably with
electron paramagnetic resonance (EPR).
6
3
Available from International Commission on Radiation Units and Measure-
The boldface numbers in parentheses refer to the bibliography at the end of this
ments, 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814, U.S.A.
standard.
7
4
Available from American National Standards Institute, 11 W. 42nd St., 13th
Annual Book of ASTM Standards, Vol 12.02.
5
Floor, New York, NY 10036. U.S.A.
Annual Book of ASTM Standards, Vol 14.02.
© ISO/ASTM International 2002 – All rights reserved
1
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ISO/ASTM 51607:2002(E)
suitable binders are cellulose, ethylene-propylene rubber, gelatin, paraffin,
application of radiofrequencies to a paramagnetic substance in
polyethylene, polyethylene vinyl acetate, polystyrene, polyvinylpyrroli-
the presence of a magnetic field.
done, polyvinyl propylene, and stearin. Lubricants added in the dosimeter
3.2.4 EPR spectrum—the first derivative of the electron
manufacturing process are optional. An example of a suitable lubricant is
paramagnetic absorption spectrum as measured as a function of
stearic acid.
the magnetic field.
6.2 Powder Dosimeters:
3.2.5 EPR signal amplitude—the peak-to-peak amplitude of
6.2.1 Alanine powder may be used directly as supplied by
the main signal of the EPR spectrum. This signal is propor-
the manufacturer.
tional to the alanine-derived radical concentration in the
alanine dosimeter.
NOTE 3—Sieving to achieve a narrower range of grain sizes from
3.2.6 zero dose amplitude—the EPR signal amplitude mea-
several tens to several hundreds of μm is recommended to improve the
surement of an unirradiated alanine dosimeter with the same
reproducibility of the EPR signal.
EPR spectrometer parameters used for the lowest measurable
6.2.2 The alanine powder is contained in a sachet or capsule
absorbed dose value.
for use. From 50 to 200 mg of powder is typically used for a
3.2.7 calibration curve—graphical representation of the
dosimeter.
mathematical relationship between the dosimeter EPR signal
6.3 Dosimeters Using Binders:
amplitude and absorbed dose, for a given type and batch of
6.3.1 Alanine dosimeters can be prepared by compressing,
alanine dosimeters.
casting, or extruding a mixture of alanine, binder, and lubricant
4. Significance and Use (optional).
6.3.2 Usual physical shapes are pellets, films, cylinders, or
4.1 The alanine-EPR dosimetry system provides a reliable
cables. The dimensions depend on the inner diameter of the
means for measuring the absorbed dose. It is based on the
microwave cavity of the EPR spectrometer, the dosimeter
generation of specific stable radicals in crystalline alanine by
holder and, the required precision of the measurement.
ionizing radiation.
6.3.3 The softening point of the binder must be compatible
4.2 The dosimeter contains crystalline alanine and registers
with the temperature during radiation exposure.
the absorbed dose by an increase in the alanine-derived radical
6.3.4 The alanine content can vary. Some published values
concentration. Identification and determination of the concen-
of the alanine content with different binders are polyvinylpyr-
tration of the specific alanine radical are performed by EPR
rolidone (95 %) (6), paraffin wax (80 to 90 %) (2, 7, 8),
spectroscopy.
polystyrene (70 %) (9), ethylene-propylene rubber (67 %) (10),
4.3 Measurement of the concentration of free radicals by
and low-density polyethylene (60 to 90 %) (11, 12). The
EPR spectroscopy is nondestructive. Alanine dosimeters can be
sensitivity of the dosimeter is proportional to the alanine
read out repeatedly and hence can be used for archival
content.
purposes.
6.3.5 The manufacturing process involves a number of
NOTE 1—For a comprehensive discussion of various dosimetry meth-
operations, for example, mortaring, sieving, binder and lubri-
ods and materials applicable to the radiation types and energies discussed
cant (optional) addition, homogenization, pressing, or extrud-
in this practice, see ASTM Practices E 178, E 668, ISO/ASTM Practices
ing. The introduction of radicals from even small amounts of
51204, 51400, 51431, ISO/ASTM Guide 51261, and ICRU Reports 14,
17, 60, 34, 35, 37, 44 and 60. paramagnetic material or from mechanical force must be
avoided during the manufacturing process. Several fabrication
4.4 Alanine-EPR dosimetry systems are used in industrial
techniques are described in Refs (12) and (13).
radiation processing, for example, sterilization of medical
6.4 Preparation Quality Assurance:
devices and pharmaceuticals, preservation of foods, polymer
6.4.1 Care shall be exercised in conducting dosimeter
modifications, and radiation damage studies in materials, as
preparation. Preparation shall be performed under clean labo-
reference or transfer standard or routine dosimetry systems.
ratory conditions and with high-quality fabrication procedures
5. Dosimeter Material
as specified in the literature (7, 14). Measurement repeatability,
interspecimen variation, and batch sensitivity may be affected
5.1 The dosimeter is prepared using a-alanine, CH -
3
CH(NH )-COOH, in the form of polycrystalline powder. by each process step.
2
6.4.2 Important factors for measurement precision are ho-
5.2 Both stereoisomers of a-alanine are suitable for dosim-
etry; L-alanine is used most commonly. mogeneity, reproducibility of mass, density, size, and shape of
the dosimeters.
5.3 The purity of the alanine shall be analytical grade (99 %
or better). Alanine of appropriate purity is commercially 6.4.3 Representative sampling of dosimeters shall be per-
formed for each production batch and subjected to quality
available. Dopants (a specific trace amount of an element as
additive) are not required. control tests, for example, visual tests of surface conditions,
impact tests, weight tests, and dimensional and density checks.
6. Preparation of Dosimeters
6.4.4 Dosimetric quality control for each production batch
6.1 The alanine dosimeter may be used in powdered form or
includes the mean batch sensitivity and interspecimen scatter-
as a solid compressed with a binder.
ing of the zero-dose-signal dosimeter response.
6.4.5 To achieve the accuracy described in 13.2, the inter-
NOTE 2—Additives used in the preparation of dosimeters should not
specimen variation of the radiation-induced response should be
add any significant intrinsic or radiation-induced EPR signal. Examples of
© ISO/ASTM International 2002 – All rights reserved
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ISO/ASTM 51607:2002(E)
within6 1 % at a 95 % confidence level. 8.2.2 Establish the calibration absorbed doses in terms of
absorbed dose in water.
7. Apparatus
8.2.3 Absorbed dose in materials other than water may be
7.1 The following equipment and instruments are necessary
calculated by applying conversion factors in accordance with
to determine the radiation-induced response of the alanine-EPR
ISO/ASTM Guide 51261.
dosimetry system:
8.2.4 Select a location in the calibration field in which the
7.1.1 The apparatus comprises an X-band EPR spectrometer
absorbed dose rate within the volume occupied by the alanine
capable of determining the alanine-derived radical concentra-
dosimeter has been demonstrated to be uniform to within
tion in a dosimeter by measurement of the EPR spectrum. A
60.5 % (1).
spectrometer capable of attaining the uncertainty limits de-
5
8.2.5 When using photons for calibration (gamma rays or
scribed in 13.2 over the dose range of 1 to 10 Gy should be
bremsstrahlung), surround the alanine dosimeter with a thick-
capable of the following settings: microwave frequency 9 to 10
ness of alanine-equivalent material to achieve approximate
GHz with automatic frequency locking (AFC); corresponding
electron equilibrium conditions.
magnetic field to set a g-factor of 2.0 (at 9.8 GHz, this equals
60
350 mT; see Note 4) with a field scan range of 20 mT about the
NOTE 5—As an example, for Co gamma-ray sources, approximately 3
center field; RF modulation amplitude 0.1 to 1 mT; microwave
to 5 mm of polystyrene, an equivalent polymeric material or alanine
power 0.1 to 10 mW (levelled); variable sweep time, time surrounding the alanine dosimeters in all directions, effectively approxi-
mates electron equilibrium conditions.
constant, and receiver gain according to absorbed dose. The
11
sensitivity of the spectrometer should be at least 2 3 10
8.2.6 Monitor and control, if possible, environmental fac-
spins/mT. The cavity should have a sample access diameter of
tors such as temperature and humidity during irradiation of the
at least 1 mm greater than the diameter of the dosimeter to be
alanine dosimeters. If possible, these should be held approxi-
analyzed.
mately constant throughout irradiation.
8.2.7 Calibrate each batch of alanine dosimeters prior to
NOTE 4—The relationship between microwave frequency (Hz) and the
magnetic field (T) is given by:
use. Use sufficient alanine dosimeters for each absorbed dose
value (see Section 9 of ASTM Practice E 668).
hv 5 gμ B (1)
B
8.2.8 The number of sets of alanine dosimeters required to
establish the calibration curve of the alanine-EPR dosimetry
where:
system depends on the dose
...
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