ISO/ASTM 51276:2002

INTERNATIONAL ISO/ASTM
STANDARD 51276
Second edition
2002-12-15
Practice for use of a
polymethylmethacrylate dosimetry
system
Pratique de l’utilisation d’un système dosimétrique au
polyméthylméthacrylate
Reference number
© ISO/ASTM International 2002
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ii © ISO/ASTM International 2002 – All rights reserved

ISO/ASTM FDIS 51276:2001(E)
Contents Page
1 Scope . 1
2 Referenced documents . 1
3 Terminology . 1
4 Significance and use . 2
5 Instrument requirements . 2
6 Performance check of instrumentation . 3
7 Calibration of the dosimetry system . 3
8 Procedures . 4
9 Characterization of each stock of dosimeters . 5
10 Application of dosimetry system . 5
11 Documentation requirements . 5
12 Measurement uncertainty . 5
13 Keywords . 6
ANNEX . 6
Bibliography . 7
Table A1.1 Basic properties of available dosimeters . 6
Table A1.2 Some suppliers of polymethylmethacrylate (PMMA) dosimeters . 6
© ISO/ASTM International 2002 – All rights reserved iii

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 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 51276 was developed by ASTM Committee E10, Nuclear Technology and
Applications, through Subcommittee E10.01, and by Technical Committee ISO/TC 85, Nuclear Energy.
Annex A1 of this International Standard is for information only.
iv © ISO/ASTM International 2002 – All rights reserved

Standard Practice for
Use of a Polymethylmethacrylate Dosimetry System
This standard is issued under the fixed designation ISO/ASTM 51276; 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 Systems for Radiation Processing
51400 Practice for Characterization and Performance of a
1.1 This practice covers procedures for using hermetically
High-Dose Radiation Dosimetry Calibration Laboratory
sealed polymethylmethacrylate (PMMA) dosimeters for mea-
51401 Practice for Use of a Dichromate Dosimetry System
suring absorbed dose in materials irradiated by photons or
51607 Practice for Use of the Alanine-EPR Dosimetry
electrons in terms of absorbed dose in water. The PMMA
System
dosimeter is classified as a routine dosimeter. See ISO/ASTM
51631 Practice for Use of Calorimetric Dosimetry Systems
Guide 51261.
for Electron Beam Dose Measurements and Dosimeter
1.2 This practice covers systems that permit absorbed dose
Calibrations
measurements under the following conditions:
51707 Guide for Estimating Uncertainties in Dosimetry for
1.2.1 the absorbed dose range is 0.1 to 100 kGy.
−2 7 −1
Radiation Processing
1.2.2 the absorbed dose rate is 1 3 10 to 1 3 10 Gy·s .
2.3 International Commission on Radiation Units and
1.2.3 the radiation energy range for photons is 0.1 to 50
Measurements (ICRU) Reports:
MeV, and for electrons 3 to 50 MeV.
ICRU Report 14 Radiation Dosimetry: X-Rays and Gamma
1.2.4 the irradiation temperature is −78 to +50°C.
Rays with Maximum Photon Energies Between 0.6 and 50
1.3 This standard does not purport to address all of the
MeV
safety concerns, if any, associated with its use. It is the
ICRU Report 17 Radiation Dosimetry: X Rays Generated at
responsibility of the user of this standard to establish appro-
Potentials of 5 to 150 kV
priate safety and health practices and determine the applica-
ICRU Report 34 The Dosimetry of Pulsed Radiation
bility of regulatory limitations prior to use.
ICRU Report 35 Radiation Dosimetry: Electron Beams with
2. Referenced documents
Energies Between 1 and 50 MeV
ICRU Report 60 Fundamental Quantities and Units for
2.1 ASTM Standards:
Ionizing Radiation
E 170 Terminology Relating to Radiation Measurements
and Dosimetry
3. Terminology
E 178 Practice for Dealing with Outlying Observations
3.1 Definitions:
E 275 Practice for Describing and Measuring Performance
3.1.1 calibration curve—graphical representation of the
of Ultraviolet, Visible, and Near Infrared Spectrophotom-
dosimetry system’s response function.
eters
3.1.2 calibration facility—combination of an ionizing radia-
E 668 Practice for Application of Thermoluminescence-
tion source and its associated instrumentation that provides a
Dosimetry (TLD) Systems for Determining Absorbed Dose
uniform and reproducible absorbed dose or absorbed-dose rate
in Radiation-Hardness Testing of Electronic Devices
traceable to national or international standards, at a specified
E 1026 Practice for Using the Fricke Reference Standard
location and within a specific material, and that may be used to
Dosimetry System
derive the dosimetry system’s response function or calibration
2.2 ISO/ASTM Standards:
curve.
51204 Practice for Dosimetry in Gamma Irradiation Facili-
3.1.3 dosimeter—a device that, when irradiated, exhibits a
ties for Food Processing
quantifiable change in some property of the device which can
51205 Practice for Use of a Ceric-Cerous Sulfate Dosimetry
be related to absorbed dose in a given material using appro-
System
priate analytical instrumentation and techniques.
51261 Guide for Selection and Calibration of Dosimetry
3.1.4 dosimeter batch—quantity of dosimeters made from a
specific mass of material with uniform composition, fabricated
This practice is under the jurisdiction of ASTM Committee E10 on Nuclear
in a single production run under controlled, consistent condi-
Technology and Applications and is the direct responsibility of Subcommittee
tions, and having a unique identification code.
E10.01 on Dosimetry for Radiation Processing, and is also under the jurisdiction of
ISO/TC 85/WG 3.
3.1.5 dosimeter response—the reproducible, quantifiable ra-
Current edition approved June 4, 2002. Published Dec. 15, 2002. Originally
diation effect produced by a given absorbed dose.
e1
published as ASTM E 1276 – 88. ASTM E 1276 - 96 was adopted by ISO in 1998
with the intermediate designation ISO 15558:1998(E). The present Second Edition
of International Standard ISO/ASTM 51276:2002(E) replaces ISO 15558, and is a
minor revision of the First Edition of ISO/ASTM 51276:2002(E).
2 4
Annual Book of ASTM Standards, Vol 12.02. Available from International Commission on Radiation Units and Measure-
ments, 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814, U.S.A.
Annual Book of ASTM Standards, Vol 03.06.
© ISO/ASTM International 2002 – All rights reserved
3.1.6 dosimeter stock—part of a dosimeter batch held by the 3.2 Definitions of other terms used in this practice that
user. pertain to radiation measurement and dosimetry may be found
3.1.7 mean specific absorbance (k¯)—average value of spe- in ASTM Terminology E 170. Definitions in E 170 are com-
cific absorbance k for a set of dosimeters irradiated to the same patible with ICRU 60; that document, therefore, may be used
absorbed dose, under the same conditions. as an alternative reference.
n
4. Significance and use
¯
k 5 k (1)
(
i
n
i21
4.1 Polymethylmethacrylate dosimetry systems are com-
monly used in industrial radiation processing, for example, in
where:
the sterilization of medical devices and the processing of foods.
n = number of dosimeters, and
In these applications, doses fall mostly within the 0.1 to 100
k = individual dosimeter specific absorbance.
i
kGy working range of the family of PMMA dosimeters.
3.1.8 measurement traceability—the ability to demonstrate
4.2 Properly selected PMMA dosimeter materials provide a
by means of an unbroken chain of comparisons that a mea-
means of directly estimating absorbed doses in near water-
surement is in agreement within acceptable limits of uncer-
equivalent substances, such as plastics, cotton, paper, gut, and
tainty with comparable nationally or internationally recognized
rubber. The doses are normally expressed in terms of dose in
standards.
water (see 4.7). Under the influence of ionizing radiation,
3.1.9 polymethylmethacrylate (PMMA) dosimeter—a piece
chemical reactions take place in the material, creating and/or
of specially selected or specially developed PMMA material
enhancing absorption bands in the visible and/or ultraviolet
that exhibits characterizable ionizing radiation-induced change
regions of the spectrum. Optical absorbance determined at
in specific optical absorbance as a function of absorbed dose,
selected wavelengths within these radiation-induced absorp-
individually sealed by the manufacturer in a hermetically
tion bands is quantitatively related to the corresponding ab-
sealed pouch.
sorbed radiation dose. Examples of appropriate wavelengths
3.1.9.1 Discussion—The PMMA, when removed from the
used for analysis of specific dosimeters are provided in Table
pouch, is commonly still referred to as the dosimeter.
A1.1.
3.1.10 reference–standard dosimeter—a dosimeter of high
4.3 In the application of a specific dosimetry system,
metrological quality, used as a standard to provide measure-
absorbed dose is obtained by using an experimentally deter-
ments traceable to, and consistent with, measurements made
mined calibration curve or response function. These are de-
using primary-standard dosimeters.
rived by measuring sets of dosimeters irradiated to known
3.1.11 response—see dosimeter response.
absorbed doses that adequately span the range of utilization of
3.1.12 response function—mathematical representation of
the system (see 7.7.2).
the relationship between dosimeter response and absorbed dose
4.4 Polymethylmethacrylate dosimetry systems require cali-
for a given dosimetry system.
bration traceable to national or international standards. See
3.1.13 routine dosimeter—a dosimeter calibrated against a
ISO/ASTM Guide 51261.
primary-, reference-, or transfer-standard dosimeter and used
4.5 During calibration and use, possible effects of condi-
for routine absorbed-dose measurement.
tions such as temperature, light exposure, energy spectrum, and
3.1.14 simulated product—a mass of material with attenu-
absorbed dose rate are taken into account.
ation and scattering properties similar to those of the product,
4.6 Unprotected PMMA dosimeter material is sensitive to
material, or substance to be irradiated.
changes in humidity, and cut pieces are therefore individually
3.1.14.1 Discussion—Simulated product is used during ir-
sealed in water-impermeable pouches during manufacture.
radiator characterization as a substitute for the actual product,
They must be kept in these sealed pouches during irradiation.
material, or substance to be irradiated. When used in routine
4.7 Absorbed dose in materials other than water may be
production runs, it is sometimes referred to as compensating
determined by applying conversion factors in accordance with
dummy. When used for absorbed-dose mapping, simulated
ISO/ASTM Guide 51261.
product is sometimes referred to as phantom material.
NOTE 1—For a comprehensive discussion of various dosimetry meth-
3.1.15 specific absorbance (k)—optical absorbance, A ,ata
l
ods applicable to the radiation types and energies discussed in this
selected wavelength l divided by the optical path length, d,as
practice, see ICRU Reports 14, 17, 34 and 35.
follows:
k 5 A /d (2)
5. Instrument requirements
l
3.1.15.1 Discussion—In this practice (ISO/ASTM 51276),
5.1 Components of the PMMA Dosimetry System—The
d is equated to dosimeter thickness (t). If t is essentially following are the components of PMMA dosimetry systems to
constant (within 61 %), calculation of specific absorbance is
determine absorbed dose:
unnecessary, and absorbance A may be taken as the dose- 5.1.1 Polymethylmethacrylate Dosimeters.
related quantity.
5.1.2 Spectrophotometer (or an equivalent instrument), ca-
3.1.16 transfer–standard dosimeter—a dosimeter, often a pable of determining optical absorbance at the analysis wave-
reference–standard dosimeter, suitable for transport between length and having documentation specifying analysis wave-
different locations, used to compare absorbed-dose measure- length range, accuracy of wavelength selection and absorbance
ments.
determination, spectral bandwidth, and stray light rejection.
© ISO/ASTM International 2002 – All rights reserved
5.1.3 Holder, to position the dosimeter reproducibly in, and see ISO/ASTM Guide 51261 and/or instrument-specific oper-
perpendicular to, the analyzing light beam. ating manuals.
5.1.4 Calibrated Standard Optical Absorption Filters, cov-
7.4 The gamma or electron-beam facility used may be an
ering more than the range of absorption encountered.
accredited calibration facility that provides an absorbed-dose
5.1.5 Calibrated Thickness Gage.
rate measured by reference– or transfer–standard dosimeters,
5.1.6 Calibrated Thickness Gage Blocks, covering more
or it may be a production irradiator. If a production irradiator
than the range of thicknesses encountered.
is used, the absorbed doses delivered to the calibration dosim-
eters shall be determined by means of reference or transfer
NOTE 2—For constant thickness dosimeters (see 3.1.15.1) the manu-
standard dosimeters irradiated together with the dosimeters to
facturer’s documentation specifying the thickness and its uniformity must
be calibrated, under conditions that ensure that the calibration-
first be verified by the user for a representative sample, and may then be
substituted for direct measurement by the user.
and corresponding reference- or transfer-standard dosimeter
sets receive the same dose, under the same environmental
5.1.7 Batch calibration curve or response function (see
conditions.
7.7.6).
7.4.1 The radiation response of PMMA dosimeters may be
affected by extremes of environmental or seasonal conditions,
6. Performance check of instrumentation
such as the absorbed–dose rate and temperature found in some
6.1 Check and record the wavelength and absorbance scales
production irradiators. In these circumstances, the use of
of the spectrophotometer at or near the analysis wavelength at
dosimeter calibrations performed at fixed dose rates and fixed
documented time intervals during periods of use, or whenever
temperatures could result in unacceptably large increases in
there are indications of poor performance. Compare and
dosimetric uncertainty. If prior experience, manufacturer’s
document this information with the instrument specifications to
recommendations, or scientific literature suggest that the range
verify adequate performance. (See ASTM Practices E 275 and
of environmental conditions experienced by the dosimeters in
E 1026.)
the production facility are likely to significantly increase the
6.2 Check the thickness gage before, and, if considered
uncertainties, then the PMMA dosimeters should be calibrated
appropriate, after, use to ensure reproducibility and absence of
in an environment that encompasses these conditions. This
zero drift. Check and record the calibration of the gage at
type of calibration may, for example, be carried out using the
documented intervals. Use gage blocks traceable to national
production irradiator, under the conditions identified, using
standards for this purpose.
reference- or transfer-standard dosimeters to determine the
calibration doses given (see 7.2.3).
7. Calibration of the dosimetry system
7.5 Absorbed doses shall be specified in terms of absorbed
7.1 Prior to use, the dosimetry system (consisting of a
dose in water, or in another specified material appropriate for
specific batch of dosimeters and specific measurement instru-
the particular application.
ments) shall be calibrated in accordance with the user’s
7.6 Provide the following conditions for the calibration of
documented procedure that specifies details of the calibration
dosimeters:
process and quality assurance requirements. This calibration
7.6.1 Ensure that the shelf-life of the dosimeters, as stated
process shall be repeated at regular intervals to ensure that the
by the manufacturer, has not been exceeded.
accuracy of the absorbed dose measurement is maintained
7.6.2 Select a well-defined and reproducible position for the
within required limits. Calibration methods are described in
dosimeters during irradiation in the calibration field. In the case
ISO/ASTM Guide 51261.
of a fixed dose rate calibration, select a location in the
7.2 Calibration Irradiation of Dosimeters—Irradiation is a
calibration field in which the variation in absorbed–dose rate
critical component of the calibration of the dosimetry system.
within the volume occupied by the dosimeters has been
Calibration irradiations shall be performed in one of three ways
demonstrated to be within 61 %, a range of 2 %. For variable
by irradiating the dosimeters at:
dose rate calibration in a production irradiator, use a location in
7.2.1 An accredited calibration laboratory that provides an
the product, or simulated product, in which the variation in
absorbed dose (or an absorbed-dose rate) having measurement
total absorbed dose delivered during production has been
traceability to nationally or internationally recognized stan-
demonstrated to be within an acceptable range such as 61%,
dards, or
a range of 2 %.
7.2.2 An in-house calibration facility that provides an ab-
7.6.3 If a calibration facility is used, the dose rate shall be
sorbed dose (or an absorbed-dose rate) having measurement
traceable to national or international standards. The tempera-
traceability to nationally or internationally recognized stan-
ture of the dosimeters, both during and after irradiation, and the
dards, or
fixed dose rate used shall be arranged
...