ISO 15570:1998

INTERNATIONAL
IS0
STANDARD
15570
First edition
1998-12-15
Practice for use of cellulose acetate
dosimetry system
Pratique d ’utilisation d ’un systkme dosimktrique de mesure 2 /‘a&ate de
cellulose
Reference number
IS0 15570: 1998(E)

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IS0 15570: 1998(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies
(IS0 member bodies). The work of preparing International Standards is normally carried out through IS0 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. IS0 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.
International Standard IS0 15570 was prepared by the American Society for Testing and Materials (ASTM)
Subcommittee E1O.O1 (as E 1650-94) and was adopted, under a special “fast-track procedure ”, by Technical
Committee ISOITC 85, Nuclear energy, in parallel with its approval by the IS0 member bodies.
A new lSO/TC 85 Working Group WG 3, High-level dosimetry for radiation processing, was formed to review the
voting comments from the IS0 “Fast-track procedure” and to maintain these standards. The USA holds the
convenership of this working group.
International Standard IS0 15570 is one of 20 standards developed and published by ASTM. The 20 fast-tracked
standards and their associated ASTM designations are listed below:
IS0 Designation ASTM Designation Title
15554 E 1204-93 Practice for dosimetty in gamma irradiation facilities for food
processing
15555 E 1205-93 Practice for use of a ceric-cerous sulfate dosimetty system
E 1261-94 Guide for selection and calibration of dosimetry systems for
15556
radiation processing
Practice for use of a radiochromic film dosimetry system
15557 E 1275-93
E 1276-96 Practice for use of a polymethylmethacrylate dosimetry system
15558
15559 E 1310-94 Practice for use of a radiochromic optical waveguide dosimetty
sys tern
15560 E 1400-95a Practice for characterization and performance of a high-dose
radiation dosimetry calibration laboratory
15561 E 1401-96 Practice for use of a dichromate dosimetry system
0 IS0 1998
reserved. Unless otherwise specified, no part of this may be reproduced utilized in any form or by any means, electronic
All rights publication or
or mecha nical, including photocopying and microfi m, without permission in writing from the p ubl isher.
International Organization for Standardization
Case postale 56 l CH-1211 Geneve 20 l Switzerland
Internet iso @I iso.ch
Printed in Switzerland
ii

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as0 IS0 15570:1998(E)
15562 E1431-91 Practice for dosimetry in electron and bremsstrahlung irradiation
facilities for food processing
15563 E 1538-93 Practice for use of the ethanol-chlorobenzene dosimetry system
15564 E 1539-93 Guide for use of radiation-sensitive indicators
E 1540-93
15565 Practice for use of a radiochromic liquid dosimetry system
15566 E 1607-94 Practice for use of the alanine-EPR dosimetry system
15567 E 1608-94 Practice for dosimetry in an X-ray (bremsstrahlung) facility for
radiation processing
Practice for use of calorimetric dosimetry systems
15568 E 1631-96 electron
beam dose measurements and dosimeter calibrations
Practice for dosimetry in an electron-beam facility for radiation
15569 E 1649-94
processing at energies between 300 keV and 25 MeV
15570 E 1650-94 Practice for use of cellulose acetate dosimetry system
E 1702-95 Practice for dosimetry in a gamma irradiation facility for radiation
15571
processing
E 1707-95 Guide for es tima ting uncertainties in radiation
15572 dosimetry for
processing
15573 E 1818-96 Practice for dosimetry in an electron-beam facility for radiation
processing at energies between 80 keV and 300 keV
. . .
III

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IS0 15570:1998(E)
@ IS0
AMERICAN SOCIETY FOR TESTING AND MATERIALS
1916 Race St Philadelphia, Pa 19103
Designation: E 1650 - 94 Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
lf not listed in the current combined index, will appear in the next edition.
Standard Practice for
Use of Cellulose Acetate Dosimetry System’
This standard is issued under the fixed designation E 1650; 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 (c) indicates an editorial change since the last revision or reapproval.
E 666 Practice for Calculating Absorbed Dose from
1. Scope
Gamma or X Radiation3
1.1 This practice covers the preparation, handling, testing
E 925 Practice for the Periodic Calibration of Narrow
and procedures for the use of cellulose acetate dosimetry
Band-Pass Spectrophotometers4
systems, and the spectrometric, densitometric, or photo-
E 958 Practice for Measuring Practical Spectral Band-
metric readout equipment for measuring absorbed dose in
width of Ultraviolet-Visible Spectrophotometers4
materials irradiated by photons and electrons in terms of
E 1026 Practice for Using the Fricke Reference Standard
absorbed dose in water.
Dosimetry System3
NOTE l-Cellulose acetate dosimeter refers to untinted and tinted
E 1205 Practice for Use of a Ceric-Cerous Sulfate
cellulose triacetate (CTA) or cellulose diacetate (CDA) film dosimeter.
Dosimetry System3
E 126 1 Guide for Selection and Calibration of Dosimetry
1.2 This practice applies to cellulose acetate film dosime-
Systems for Radiation Processing3
ters that can be used within part or all of the specified ranges
E 1275 Practice for Use of a Radiochromic Film
as follows:
1.2.1 The absorbed dose range for untinted CTA and Dosimetry System3
CDA is 5 x lo3 to 3 x lo5 Gy for photons and electrons, E 1276 Practice for Use of a Polymethlmethacrylate
1.2.2 The absorbed dose range for tinted CTA and CDA is
Dosimetry System3
1 x lo4 to 1 x lo6 Gy for photons and electrons, E 13 10 Practice for Use of a Radiochromic Optical
1.2.3 The absorbed dose rate for both CTA and CDA is
Waveguide Dosimetry System3
from 0.03 to 3 x 10’ Gy/s,
E 1400 Practice for Characterization and Performance of a
1.2.4 The radiation energy range for photons is from 0.1
High-Dose Gamma Radiation Dosimetry Calibration
to 50 MeV, and
Laboratory3
1.25 The radiation energy range for electrons is from 0.2
E 1401 Practice for Use of a Dichromate Dosimetry
to 50 MeV.
System3
E 1538 Practice for Use of the Ethanol-Chlorobenzene
NOTE 2-In cases where low-energy electrons and charged particles
Dosimetry System3
cannot completely penetrate the thickness of standard CTA and CDA
E 1540 Practice for Use of a Radiochromic Liquid Solu-
films, thin films may be used (1, 2).2
tion Dosimetry System3
1.2.6 The irradiation temperature range is from - 10 to
E 1607 Practice for Use of the Alanine-EPR Dosimetry
70°C.
System3
1.3 This standard does not purport to address all of the
E 1608 Practice for Dosimetry in an X-Ray
safety concerns, zf any, associated with its use. It is the
(Bremsstrahlung) Irradiation Facility for Radiation
responsibility of the user of this standard to establish appro-
Processing3
priate safety and health practices and determine the applica-
E 163 1 Practice for Use of Calorimetric Dosimetry Sys-
bility of regulatory limitations prior to use.
tems for Electron Beam Dose Measurements and Do-
simeter Calibrations3
2. Referenced Documents E
1649 Practice for Dosimetry in an Electron Beam
Facility for Radiation Processing at Energies between
2.1 ASTM Standards:
300 keV and 25 MeV
E 170 Terminology Relating to Radiation Measurements
2.2 International Commission on Radiation Units and
and Dosimetry3
Measurement (ICR U) Reports?
E 275 Practice for Describing and Measuring Performance
ICRU Report 14 Radiation Dosimetry: X-Rays and
of Ultraviolet, Visible, and Near Infrared Spectropho-
Gamma Rays with Maximum Photon Energies Between
tometers
0.6 and 50 MeV
ICRU Report 17 Radiation Dosimetry: X-Rays and
Gamma Rays at Potentials of 5 to 150 kV
* This practice is under the jurisdiction of ASTM Committee E- 10 on Nuclear
Technology and Applications and is the direct responsibility of Subcommittee
ICRU Report 33 Radiation Quantities and Units
E 10.01 on Dosimetry for Radiation Processing.
ICRU Report 34 The Dosimetry of Pulsed Radiation
Current edition approved Nov. 15, 1994. Published February 1995.
2 The boldface numbers in parentheses refer to the list of references at the end
of this practice.
5 Available from International Commission on Radiation Units and Measure-
3 Annual Book of ASTM Standards, Vol 12.02.
4 Annual Book of ASTM Standards, Vol 03.06. ment, 7910 Woodmont Ave., Suite 800, Bethesda, MD 208 14.
1

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ISO15570:1998( E)
@ IS0
ICRU Report 35 Radiation Dosimetry: Electron Beams and the optical absorbance of an irradiated film dosimeter,
with Energies Between 1 and 50 MeV
A.
ICRU Report 37 Stopping Powers for Electrons and
AA = A - A, (for increasing absorbance) .
Positrons
AA =A, - A (for decreasing absorbance)
ICRU Report 44 Tissue Substitutes in Radiation Dosim-
etry and Measurement 3.11 net optical density, AOD-another expression for
“net absorbance.”
3. Terminology
DIscussroN-This expression is more commonly used for film and
plastic dosimeters than for liquid dosimeters.
3.1 absorbed dose, D-quotient of &by dm, where dF is
the mean energy imparted by ionizing radiation to matter of
3.12 speciJic net absorbance, k-net absorbance, AA, at a
mass dm (see Terminology E 170 and ICRU Report 33).
selected wavelength divided by the optical path length, t,
The special name for the unit of absorbed dose is the gray
through the dosimeter (that is, film thickness) as follows:
GYk
k=hA/t
1 Gy= 1 Jekg-’
3.13 stock-part of a dosimeter batch, held by the user.
Formerly, the special unit for absorbed dose was the rad:
3.14 traceability-the ability to show that a measurement
lo-*J*kg-l
1 rad = is consistent with appropriate national or international
standards through an unbroken chain of comparisons.
3.2 absorbed dose mapping-measurement of the ab-
3.15 Other appropriate terms may be found in Termi-
sorbed-dose distribution in an irradiation unit through the
nology E 170.
use of dosimeters placed at specified locations throughout
the product volume.
4. Significance and Use
3.3 analysis wavelength-wavelength used in a spectro-
4.1 The cellulose acetate (CTA and CDA) dosimetry
or photometer for measuring
photometer, densitometer,
systems provide a means of measuring absorbed dose in
optical absorbance.
materials (3-17). Under the influence of radiation, chemical
3.4 calibration curve-graphical or mathematical rela-
reactions take place in the cellulose acetate, plasticizer or
tionship between dosimeter response and absorbed dose for a
dyes in the matrix, changing the optical absorption proper-
given dosimetry system; this term is also referred to as the
ties (absorption wavelength (band) and density) (18).
response function.
Absorbance or optical density values are measured at the
3.5 ceMose acetate dosimeter-untinted and tinted cellu-
selected wavelength using a spectrophotometer, densitom-
lose triacetate (CIA) or cellulose diacetate (CDA) film
eter, or photometer.
dosimeters that undergo change in optical absorbance or
4.2 In the use of a specific dosimetry system, absorbed
optical density under ionizing radiation.
dose is evaluated by the use of a calibration curve traceable
DIscussroN-This change in absorbance or optical density is related
to national or international standards.
to radiation chemical change in cellulose acetate, plasticizer and tinted
4.3 Absorbed dose that is measured is usually specified in
dyes, and can be related to absorbed dose in water.
water. Absorbed dose in other materials may be evaluated by
applying the conversion factors discussed in Guide E 126 1.
3.6 dosimeter batch-a quantity of dosimeters made from
a specific mass of dosimetric material with uniform compo-
NOTE 3-For a comprehensive discussion of various dosimetry
sition, fabricated in a single production run under controlled,
methods applicable to the radiation types and energies discussed in this
consistent conditions, and having a unique identification practice, see ICRU Reports 14, 17, 34, 35, and 37.
code.
4.4 These dosimetry systems may be used in the industrial
3.7 dosimetry system- a system for determining absorbed
radiation processing of various products, for example radia-
dose, consisting of dosimeters, measurement instruments
tion effects tests, polymer modifications, and sterilization of
and their associated reference standards, and procedures for
medical devices.
the system ’s use.
4.5 The available dynamic ranges indicated in 1.2.1 and
3.8 electron equilibrium- a condition that exists in a
1.2.2 are achieved by using a variety of plasticizer and dye
material under irradiation when the energies, number, and
concentrations in the CTA and CDA systems.
direction of electrons induced by the radiation are constant
4.6 The difference in dose response due to changes in the
throughout the volume of interest; thus, within such a
parameters of the irradiation conditions, such as dose rate,
volume, the sum of the energies of all electrons entering it is
temperature, humidity, and atmosphere should be consid-
equal to the corresponding sum of all electrons leaving it.
ered when these are different from the parameters of the
3.9 measurement quality assurance plan-a documented
calibration.
program for the measurement process that quantifies the
NOTE 4-The dose response of the CTA dosimeter increases linearly
total uncertainty of the measurements (both random and
with temperature (-10 to 4O ’C) and relative humidity (20 to 80 %I)
systematic error components); this plan shall demonstrate
when irradiated at lower dose-rates (< 10 kGy/h) typical of gamma-
traceability to national standards, and shall show that the
irradiators. The effects are found to be less severe at the higher dose-rates
total uncertainty meets the requirements of the specific
for electron irradiators (> 100 kGy/h). Moreover, as mentioned in Ref
application.
16, these effects are known to vary from batch to batch. All these effects
3.10 net absorbance, AA-the difference between the
need to be considered before CTA dosimeters can be used routinely for
optical absorbance of an unirradiated film dosimeter, A,, processing (6, 9, 11, 12, 16, and 17).
2
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@ IS0
IS0 15570:1998(E)
5. Apparatus
5.1 The following shall be used to evaluate absorbed dose
with cellulose acetate dosimetry systems:
5.1.1 A batch or portion of a batch of cellulose acetate
film.
5.1.2 A double-beam UV/visible spectrophotometer or an
equivalent instrument having documentation covering: (I)
the analytical wavelength at which absorbance or optical
density is measured (see 8.2); (2) the accuracy of wavelength
selection, absorbance or optical density reading (see Figs. 1
through 4 for suitable wavelength-for example, 280 nm for
CTA and 390 nm for dyed CDA); and (3) the spectral
wavelength range (in the case of absorption spectral readout
as discussed in Ref 16). In addition, stray light rejection is
needed. The spectrophotometer or the equivalent instrument
should also be able to read the absorbance up to a value of
2.0 at a suitable wavelength with an uncertainty of no more
O------J
than +l %. 0 100 200 300
Oose in CIA ( ~GY )
5.1.3 A film holder for spectrophotometry, or equivalent
NOTE 1-O: electron beam (dose rate: 10’ Gy/h, temperature: 15OC, relative
device, should keep the film perpendicular to the analytical
humidity: 60 X). 0: gamma-rays (dose rate: 1 O4 Gy/h, temperature 25OC, relative
beam, or a built-in automatic film feeder at a speed of the
humidity: 50 to 60 %)
order of 0.1 to 1 cm/s with the same specifications of the film
NOTE 2-The AA values were measured 2 h after irradiation (19).
holder used for automatic one-dimensional dose profile
FIG. 2 The Relation Between the Increment of Absorbance
measurement.
AA/Nominal Thickness (0.125 mm) at 280 nm and Dose in Untinted
51.4 The thickness gage shall be calibrated and traceable CTA by Electron and Gamma-Radiation
to a national standard within a precision oft 1 % of the film
thickness at the 95 % confidence level.
there are indications of poor performance.
6.1.3 Document the comparison of information obtained
6. Performance Check of Instrumentation
in 6.1.1 or 6.1.2 with the original instrument specifications
to verify adequate performance or take appropriate correc-
6.1 Check and document the performance of a
tive action if required (see Practice E 275 and Section 9 of
spectrophotometer or an equivalent instrument, for ex-
Practice E 1026).
ample, a densitometer or photometer equipped with a
narrow band-pass filter at a suitable wavelength (see Prac-
7. Preparation of Dosimeters
tices E 275, E 925, E 958, and E 1026).
7.1 Cellulose acetate dosimeters can be prepared by
6.1.1 When using a densitometer or photometer, estimate
pouring a prescribed recipe solution (for example, see Ref 5)
and document the precision and bias of the absorbance or
consisting of cellulose diacetate or triacetate, plasticizer, dye,
optical density scale at time intervals not to exceed one
and solvent onto an optical flat plate and evaporating the
month during the period of use, or whenever there are
solvent slowly and gently. The thickness of the film can be
indications of poor performance.
controlled by the concentration of solutes or by the amount
6.1.2 When using a spectrophotometer, estimate and
of solution poured on to a given area of the horizontal plate.
document the precision and bias of the wavelength scale at or
7.1.1 For both untinted and tinted CTA dosimeter films,
near the selected analytical wavelength(s), at intervals not to
the recommended recipe is 85 weight % of cellulose
exceed one month during the period of use, or whenever
triacetate and balance of triphenyl phosphate (TPP) as a sole
plasticizer, plus compatible kinds and amounts of solvents,
for example, methylenechloride-methanol mixture (18).
7.2 In-house preparation of cellulose acetate dosimeters
has an advantage that the film thickness can be adjusted
according to the intended application, the measurable dose
range and the range of the electron beam. The disadvantage
lies in the difficulty in making a large size film of constant
thickness. Such film may be used for small size dosimeters
but, unless the thickness is uniform, may not be used as long
strips or large size films for continuous dose mapping
270
purposes.
Wavelength (nm)
7.3 Some CTA and CDA films are commercially avail-
NOTE-The suggested wavelength of 280 nm is chosen due to low absorbance
able, and are described in the nonmandatory appendix of
before irradiation (A,), and linear absorbance (A) increase with dose. (Original
this practice.
drawing by the author of Refs 1, 2, and 19)
FIG. 1 Absorption Spectra Before and After Irradiation of
8. Calibration of Dosimeters
Untinted Cellulose Triacetate (CTA) Film with a 2 MeV Electron
Beam 8.1 Irradiation:
3
3

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IS0 15570:1998(E) 0 IS0
an irradiation facility that has a dose rate traceable to
p-L--
appropriate national or international standards and that
m
0 (unlrrod.)
meets the requirements specified in Practice E 1400. Use a
reference or transfer dosimetry system to- establish the
YELLOW CDA
traceability (see Guide E 126 1, and P
...