ASTM E666-97
(Practice)Standard Practice for Calculating Absorbed Dose From Gamma or X Radiation
Standard Practice for Calculating Absorbed Dose From Gamma or X Radiation
SCOPE
1.1 This practice presents a technique for calculating the absorbed dose in a material from knowledge of the radiation field, the composition of the material, (1) and a related measurement. The procedure is applicable for X and gamma radiation provided the energy of the photons fall within the range from 0.01 to 20 MeV.
1.2 A method is given for calculating the absorbed dose in a material from the knowledge of the absorbed dose in another material exposed to the same radiation field. The procedure is restricted to homogeneous materials composed of the elements for which absorption coefficients have been tabulated (2). It also requires some knowledge of the energy spectrum of the radiation field produced by the source under consideration. Generally, the accuracy of this method is limited by the accuracy to which the energy spectrum of the radiation field is known.
1.3 The results of this practice are only valid if charged particle equilibrium exists in the material and at the depth of interest. Thus, this practice is not applicable for determining absorbed dose in the immediate vicinity of boundaries between materials of widely differing atomic numbers. For more information on this topic, see Practice E1249.
1.4 This practice does not consider dose "buildup" due to broad-beam geometry. Such "buildup" depends on the energy spectrum of the radiation field and the effective atomic number of the material. Correction can be made if buildup factors are included in the attenuation calculation. These factors have not been tabulated for a wide range of energies, geometries, and materials (3,4,5). However, this method has utility in providing a quick and relatively simple way of achieving useful approximate results.
1.5 Energy transport computer codes exist that are formulated to calculate absorbed dose in materials more precisely than this method. To use these codes, more effort, time, and expense are required. If the situation warrants, such calculations should be used rather than the method described here.
1.6 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: E 666 – 97
Standard Practice for
1
Calculating Absorbed Dose From Gamma or X Radiation
This standard is issued under the fixed designation E 666; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
1.1 This practice presents a technique for calculating the
absorbed dose in a material from knowledge of the radiation
2. Referenced Documents
2,3
field, the composition of the material, (1-5) and a related
2.1 ASTM Standards:
measurement. The procedure is applicable for X and gamma
E 170 Terminology Relating to Radiation Measurements
radiation provided the energy of the photons fall within the
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and Dosimetry
range from 0.01 to 20 MeV.
E 380 Practice for Use of the International System of Units
1.2 A method is given for calculating the absorbed dose in
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(SI) (the Modernized Metric System)
a material from the knowledge of the absorbed dose in another
E 665 Practice for Determining Absorbed Dose Versus
material exposed to the same radiation field. The procedure is
Depth in Materials Exposed to the X-Ray Output of Flash
restricted to homogeneous materials composed of the elements
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X-Ray Machines
for which absorption coefficients have been tabulated (2). It
E 668 Practice for Application of Thermoluminescence-
also requires some knowledge of the energy spectrum of the
Dosimetry (TLD) Systems for Determining Absorbed Dose
radiation field produced by the source under consideration.
5
in Radiation-Hardness Testing of Electronic Devices
Generally, the accuracy of this method is limited by the
E 1249 Practice for Minimizing Dosimetry Errors in Radia-
accuracy to which the energy spectrum of the radiation field is
tion Hardness Testing of Silicon Electronic Devices Using
known.
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Co-60 Sources
1.3 The results of this practice are only valid if charged
2.2 International Commission on Radiation Units and
particle equilibrium exists in the material and at the depth of
Measurements (ICRU) Reports:
interest. Thus, this practice is not applicable for determining
ICRU Report 14—Radiation Dosimetry: X Rays and
absorbed dose in the immediate vicinity of boundaries between
Gamma Rays with Maximum Photon Energies Between
materials of widely differing atomic numbers. For more infor-
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0.6 and 60 MeV
mation on this topic, see Practice E 1249.
4 ICRU Report 18—Specification of High Activity Gamma-
1.4 Energy transport computer codes exist that are formu-
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Ray Sources
lated to calculate absorbed dose in materials more precisely
ICRU Report 21—Radiation Dosimetry: Electrons with Ini-
than this method. To use these codes, more effort, time, and
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tial Energies Between 1 and 50 MeV
expense are required. If the situation warrants, such calcula-
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ICRU Report 33—Radiation Quantities and Units
tions should be used rather than the method described here.
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ICRU Report 34—The Dosimetry of Pulsed Radiation
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3. Significance and Use
responsibility of the user of this standard to establish appro-
3.1 The absorbed dose is a more meaningful parameter than
exposure for use in relating the effects of radiation on materi-
als. It expresses the energy absorbed by the irradiated material
1
This practice is under the jurisdiction of ASTM Committee E-10 on Nuclear
per unit mass, whereas exposure is related to the amount of
Technology and Applications and is the direct responsibility of Subcommittee
charge produced in air per unit mass. Absorbed dose, as
E 10.07 on Radiation Dosimetry for Radiation Effects on Materials and Devices.
Current edition approved June 10, 1997. Published May 1998.
referred to here, implies that the measurement is made under
2
The boldface numbers in parentheses refer to the list of references appended to
conditions of charged particle (electron) equilibrium (see
this practice.
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Appendix X1). In practice, such conditions are not rigorously
For calculation of absorbed dose in biological materials such as tissue or bone,
etc., ICRU Report 14 provides more information and procedures for a more accurate
calculation than this practice.
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Information on and packages of computer codes can be obtained from The
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Radiation Safety Information Computational Center, Oak Ridge National Labora- Annual Book of ASTM Standards, Vol 12.02.
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tory, P.O. Box 2008, Oak Ridge, TN 37831-6362. This information center collects
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