ISO/ASTM 51650:2005

Practice for use of a cellulose triacetate dosimetry system

ISO/ASTM 51650:2005 covers procedures for using the cellulose triacetate (CTA) dosimetry system for measuring absorbed dose and dose profile in materials irradiated by electrons and photons in terms of absorbed dose to water. The CTA dosimeter is a routine dosimeter especially useful for measurement of dose distribution.

Pratique de l'utilisation d'un système dosimétrique au triacétate de cellulose

General Information

• Status: Withdrawn
• Publication Date: 21-Jul-2005
• Withdrawal Date: 21-Jul-2005
• 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: 15-May-2013

Relations

• Revised: ISO/ASTM 51650:2013 - Practice for use of a cellulose triacetate dosimetry system
• Effective Date: 20-Oct-2012
• Revises: ISO/ASTM 51650:2002 - Practice for use of a cellulose triacetate dosimetry system
• Effective Date: 15-Apr-2008

Standards Content (Sample)

INTERNATIONAL ISO/ASTM
STANDARD 51650
Second edition
2005-05-15
Practice for use of a cellulose triacetate
dosimetry system
Pratique de l’utilisation d’un système dosimétrique au triacétate
de cellulose
Reference number
ISO/ASTM 51650:2005(E)
© ISO/ASTM International 2005

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ISO/ASTM 51650:2005(E)
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ii © ISO/ASTM International 2005 – All rights reserved

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ISO/ASTM FDIS 51650:2005(E)
Contents Page
1 Scope . 1
2 Referenced documents . 1
3 Terminology . 1
4 Significance and use . 2
5 Instrument required . 3
6 Preparation of dosimeter . 3
7 Calibration of the dosimetry system . 3
8 Measurement . 4
9 General practice . 4
10 Environmental and other interferences . 5
11 Minimum documentation required . 5
12 Measurement uncertainty . 5
13 Keywords . 6
ANNEX . 6
Bibliography . 6
Figure 1 The relation between specific net absorbance DA /d at 280 nm and absorbed dose in
60
water for 1 MeV electron beam and Co gamma-ray irradiation . 3
Figure 2 Absorption spectra before and after irradiation of CTA dosimeter film with 2 MeV electron
beam . 4
Figure 3 Relative dose response of CTA dosimeter (FTR-125) in air, as a function of average
absorbed-dose rate . 5
Table A1.1 Basic properties of available CTA dosimeter . 6
Table A1.2 Examples of absorbance measuring devices for cellulose triacetate dosimeters . 7
© ISO/ASTM International 2005 – All rights reserved iii

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ISO/ASTM 51650:2005(E)
Foreword
ISO(theInternationalOrganizationforStandardization)isaworldwidefederationofnationalstandardsbodies
(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 51650 was developed byASTM Committee E10, Nuclear Technology and
Applications, through Subcommittee E10.01, and by Technical Committee ISO/TC 85, Nuclear energy.
This second edition cancels and replaces the first edition (ISO/ASTM 51650:2002), which has been
technically revised.
iv © ISO/ASTM International 2005 – All rights reserved

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ISO/ASTM 51650:2005(E)
Standard Practice for
1
Use of a Cellulose Triacetate Dosimetry System
This standard is issued under the fixed designation ISO/ASTM 51650; 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 E925 PracticeforthePeriodicCalibrationofNarrowBand-
Pass Spectrophotometers
1.1 This practice covers procedures for using the cellulose
E958 Practice for Measuring Practical Spectral Bandwidth
triacetate (CTA) dosimetry system for measuring absorbed
of Ultraviolet-Visible Spectrophotometers
dose and dose profile in materials irradiated by electrons and
3
2.2 ISO/ASTM Standards:
photonsintermsofabsorbeddosetowater.TheCTAdosimeter
51261 Guide for Selection and Calibration of Dosimetry
is a routine dosimeter especially useful for measurement of
Systems for Radiation Processing
dose distribution.
51400 Guide for Characterization and Performance of a
NOTE 1—Cellulose triacetate dosimeter refers to untinted film dosim-
High-Dose Radiation Dosimetry Calibration Laboratory
eter.
51707 Guide for Estimating Uncertainties in Dosimetry for
1.2 This practice applies provided the following conditions
Radiation Processing
are satisfied.
2.3 International Commission on Radiation Units and
4
1.2.1 The absorbed-dose range is 10 kGy to 300 kGy for
Measurements (ICRU) Reports:
electrons and photons.
ICRU Report 14 Radiation Dosimetry: X Rays and Gamma
10
1.2.2 The absorbed-dose rate range is 3 Gy/s to 4310
RayswithMaximumPhotonEnergiesBetween0.6and50
2
Gy/s (1).
MeV
1.2.3 The radiation-energy range for electrons is 0.2 to 50
ICRUReport17 RadiationDosimetry:XRaysGeneratedat
MeV.
Potentials of 5 to 150 kV
1.2.4 The radiation-energy range for photons is 0.1 to 50
ICRU Report 34 The Dosimetry of Pulsed Radiation
MeV.
ICRUReport35 RadiationDosimetry:ElectronBeamswith
1.2.5 The irradiation-temperature range of the dosimeter is
Energies Between 1 and 50 MeV
–10 to 70°C.
ICRU Report 37 Stopping Powers for Electrons and
1.3 This standard does not purport to address all of the
Positrons
safety concerns, if any, associated with its use. It is the
ICRU Report 60 Fundamental Quantities and Units for
responsibility of the user of this standard to establish appro-
Ionizing Radiation
priate safety and health practices and determine the applica-
3. Terminology
bility of regulatory limitations prior to use.
3.1 Definitions:
2. Referenced documents
3.1.1 absorbed-dose mapping—measurement of absorbed
3
2.1 ASTM Standards:
dosewithinaprocessloadusingdosimetersplacedatspecified
E170 Terminology Relating to Radiation Measurements
locations to produce a one-, two- or three-dimensional distri-
and Dosimetry
bution of absorbed dose, thus rendering a map of absorbed-
E177 PracticeforUseoftheTermsPrecisionandAccuracy
dose values.
as Applied to Measurement of a Property of a Material
3.1.1.1 Discussion—The CTA dosimeter strip with appro-
E178 Practice for Dealing With Outlying Observations
priate length provides continuous measurement of one-
dimensional dose distribution.
·
1 3.1.2 absorbed-dose rate (D)—absorbed dose in a material
This practice is under the jurisdiction of ASTM Committee E10 on Nuclear
Technology and Applications and is the direct responsibility of Subcommittee per incremental time interval, that is, the quotient of dD by dt.
E10.01 on Dosimetry for Radiation Processing, and is also under the jurisdiction of
dD
ISO/TC 85/WG 3.
˙
D 5 (1)
dt
Current edition approved by ASTM June 1, 2004. Published May 15, 2005.
Originally published asASTM E 1650–94 with title: Practice for Use of Cellulose −1
Unit: Gy·s .
Acetate Dosimetry Systems. ASTM E 1650–94 was adopted by ISO in 1998 with
theintermediatedesignationISO15570:1998(E).ThepresentInternationalStandard
3.1.2.1 Discussion—(1) The absorbed-dose rate is often
ISO/ASTM 51650:2005(E) is a major revision of the last previous edition
specified in terms of its average value over longer time
ISO/ASTM 51650:2002(E), which replaced ISO 15570.
−1 −1
2 intervals,forexample,inunitsofGy·min orGy·h .(2)In
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
this standard.
3
For referenced ASTM and ISO/ASTM standards, visit the ASTM website,
www.astm.org, or contact ASTM Customer Service at [e-mail]. For
4
Annual Book of ASTM Standards volume information, refer to the standard’s AvailablefromtheInternationalCommissiononRadiationUnitsandMeasure-
Document Summary page on the ASTM website. ments, 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814, USA.
© ISO/ASTM International 2005 – All rights reserved
1

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ISO/ASTM 51650:2005(E)
gamma industrial irradiators, dose rate may be significantly in Terminology E170. Definitions in E170 are compatible
different at different locations. (3) In electron-beam facilities with ICRU 60; that document, therefore, may be used as an
with pulsed or scanned beam, there are two types of dose rate; alternative reference.
average value over several pulses (scans) and instantaneous
value within a pulse (scan). These two values can be signifi-
4. Significance and use
cantly different.
4.1 The cellulose triacetate (CTA) dosimetry system pro-
3.1.3 analysis wavelength—wavelength used in a spectro-
videsameansformeasuringabsorbeddoseinmaterials(2-15).
photometric instrument for the measurement of optical absor-
The dosimeter is a film containing cellulose triacetate and
bance or reflectance.
plasticizer.Thedosimetryisbasedonchemicalreactionsinthe
3.1.4 calibration curve—graphical representation of the
film resulting in changes in the optical absorption properties in
dosimetry system’s response function.
near ultraviolet region. The absorbance is measured at a
3.1.5 cellulose triacetate dosimeter—untintedCTAfilmthat
specific wavelength using a spectrophotometer or equivalent
undergoes change in optical absorbance under irradiation.
photometric instruments.
3.1.6 charged-particle equilibrium—condition that exists in
4.2 Absorbeddoseisevaluatedbyuseofacalibrationcurve
anincrementalvolumewithinamaterialunderirradiationifthe
or response function traceable to nationally or internationally
kineticenergiesandnumberofchargedparticles(ofeachtype)
recognized standards.
entering that volume are equal to those leaving that volume.
3.1.6.1 Discussion—When electrons are the predominant 4.3 Absorbed dose is usually specified in terms of absorbed
chargedparticles,theterm“electronequilibrium”isoftenused
dose to water. Absorbed dose to other materials may be
to describe charged-particle equilibrium.
evaluated by applying the conversion factors discussed in
3.1.7 dosimeter batch—quantity of dosimeters made from a ISO/ASTM Guide 51261.
specific mass of material with uniform composition, fabricated
NOTE 2—For a comprehensive discussion of various dosimetry meth-
in a single production run under controlled, consistent condi-
ods applicable to the radiation types and energies discussed in this
tions and having a unique identification code.
practice, see ICRU Reports 14, 17, 34, 35, and 37.
3.1.8 dosimetry system—system used for determining ab-
4.4 This dosimetry system may be used in industrial radia-
sorbed dose, consisting of dosimeters, measurement instru-
ments and their associated reference standards, and procedures tion processing of various products, for example radiation
for the system’s use. effecttests,polymermodifications,andsterilizationofmedical
devices.
3.1.9 electron equilibrium—charged-particle equilibrium
for electrons. See charged-particle equilibrium.
4.5 Aone-dimensionalabsorbed-dosemappingonorwithin
3.1.10 measurement quality assurance plan—documented
a product may be obtained by irradiating a dosimeter strip of
program for the measurement process that ensures that the
appropriate length.
expanded uncertainty consistently meets the requirements of
4.6 The absorbed-dose range indicated in 1.2.1 may be
the specific application.This plan requires measurement trace-
achieved by using triphenylphosphate (TPP) as the sole plas-
ability to nationally or internationally recognized standards.
ticizer in the dosimeter.
3.1.11 measurement traceability—ability to demonstrate by
4.7 The effect on the dosimeter response due to changes in
means of an unbroken chain of comparisons that a measure-
theirradiationconditions,suchasabsorbed-doserate,tempera-
ment is in agreement within acceptable limits of uncertainty
ture, humidity, and atmosphere should be considered when
with comparable nationally or internationally recognized stan-
these are different from the calibration conditions.
dards.
4.7.1 The dosimeter has different responses to electron
3.1.12 net absorbance (DA)—change in measured optical
beams at relatively high dose rates than to gamma radiation at
absorbanceataselectedwavelengthdeterminedastheabsolute
relatively low dose rates (see Fig. 1). Calibration should be
difference between the pre-irradiation absorbance, A , and the
0
carried out separately for each type of radiation.
post-irradiation absorbance, A as follows:
4.7.2 The dosimeter response increases linearly with tem-
DA 5?A 2 A ? (2)
0
perature from –10 to 60°C at 7 kGy/h, and from –10 to 40°C
3.1.13 routine dosimeter—dosimeter calibrated against a
at 1.2 kGy/h (7), and with relative humidity (up to 80%)
primary-, reference-, or transfer-standard dosimeter and used
during irradiation when irradiated at lower dose rates (<10
for routine absorbed-dose measurements.
kGy/h) typical of gamma irradiators. The effects are not
3.1.14 specific net absorbance (Dk)—net absorbance, DA ,
l
appreciable at higher absorbed-dose rates (>100 kGy/h). All
at a selected wavelength, l, divided by the optical pathlength,
theseeffectsneedtobeconsideredbeforethedosimetercanbe
d, through the dosimeter as follows:
used routinely for processing (4,7,12,15). For high-dose-rate
Dk5DA /d (3)
l
dosimetry (for example, electron beams) the influence of
3.1.15 stock—part of a dosimeter batch, held by the user. humidity on dosimeter response is not appreciable (4,7). For
3.1.16 traceability—see measurement traceability. other conditions it is recommended to calibrate the dosimetry
3.1.17 Definitions of other terms used in this practice that system by the final user under specific environmental condi-
pertain to radiation measurement and dosimetry may be found tions.
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ISO/ASTM 51650:2005(E)
60
FIG. 1 The relation between specific net absorbanceDA /d at 280 nm and absorbed dose in water for 1 MeV electron beam and Co
gamma-ray irradiation
5. Instrument required 6. Preparation of dosimeter
6.1 The dosimeter strip of 8 mm width and 100 m length
5.1 Components of Dosimetry System—The following shall
rolledonaspooliscommerciallyavailable,andisdescribedin
be used to determine absorbed dose with the film dosimetry
the informative annex of this practice.
system.
6.2 In-house preparation has an advantage that the film
5.1.1 Cellulose Triacetate Dosimeter—TheCTAdosimeters
thickness can be adjusted according to the intended applica-
are in the form of pieces and strips with appropriate width,
tion. In making long dosimeter strips, which is required for
length and thickness. For most applications, the width and the
dose mapping, the uniformity in thickness is necessary.
thickness of the dosimeter are 8 mm and 0.125 mm, respec-
tively. 6.3 The dosimeter can be cast by pouring a prescribed
recipe solution consisting of cellulose triacetate, plasticizer,
5.1.2 Spectrophotometer(orequivalentinstrument),capable
and solvent onto an optically flat horizontal plate and evapo-
of measuring optical absorbance values up to 2 with an
rating the solvent slowly. The thickness of the film can be
uncertainty of no more than 61% at the analysis wavelength
controlled by the concentration of solutes or by the amount of
(280 nm) and having documentation covering analysis wave-
solution poured on to a given area of the horizontal plate.
length range, absorbance determination, spectral bandwidth
6.4 The recommended recipe is 70 to 85 weight% of
and the reproducibility (See ASTM Practices E925 and
cellulosetriacetateandbalanceoftriphenylphosphate(TPP)as
E958).
a sole plasticizer, and solvents, for example,
5.1.3 Film Holder (or equivalent device), to position the
methylenechloride-methanol mixture (13).
dosimeter piece reproducibly in, and perpendicular to the
analysis light path.Abuilt-in automatic dosimeter strip feeder
7. Calibration of the dosimetry system
with the same capability as the static film
...