ISO 15561:1998

INTERNATIONAL IS0
STANDARD 15561
First edition
19984245
Practice for use of a dichromate dosimetry
system
Utilisation d ’un syst&me de mesure dosimdtrique au dichromate
Reference number
IS0 15561:1998(E)

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IS0 15561:1998(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 15561 was prepared by the American Society for Testing and Materials (ASTM)
Subcommittee E1O.O1 (as E 1401-96) and was adopted, under a special “fast-track procedure ”, by Technical
Committee ISO/TC 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 15561 is one of 20 standards developed and published by ASTM. The 20 fast-tracked
standards and their associated ASTM designations are listed below:
Title
IS0 Designation ASTM Designation
15554 E 1204-93 Practice for dosimetry in gamma irradiation facilities for food
processing
15555 E 1205-93 Practice for use of a ceric-cerous sulfate dosimetry system
15556 E 1261-94 Guide for selection and calibration of dosimetry systems for
radiation processing
Practice for use of a radiochromic film dosimetry system
15557 E 1275-93
15558 E 1276-96 Practice for use of a polymethylmethacaylate dosimetty system
Practice for use of a radiochromic optical waveguide dosimetry
15559 E 1310-94
system
Practice for characterization and performance of a high-dose
15560 E 1400-95a
radiation dosimetry calibration labora tory
15561 E 1401-96 Practice for use of a dichromate dosimetry system
0 IS0 1998
All rights reserved. Unless otherwise specified, no pa rt of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and mic rofilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 l CH-1211 Geneve 20 l Switzerland
Internet iso @? iso.ch
Printed in Switzerland

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IS0 15561:1998(E)
@ IS0
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
15565 E 1540-93 Practice for use of a radiochromic liquid dosimetry system
15566 E 1607-94 Practice for use of the alanine-EPF? dosimetry system
15567 E 1608-94 Practice for dosimetry in an X-ray (bremsstrahlung) facility for
radiation processing
15568 E 1631-96 Practice for use of calorimetric dosimetry systems for electron
beam dose measurements and dosimeter calibrations
15569 E1649-94 Practice for dosimetry in an electron-beam facility for radiation
processing at energies between 300 ke V and 25 Me V
E 1650-94 Practice for use of cellulose acetate dosimetry system
15570
15571 E 1702-95 Practice for dosimetry in a gamma irradiation facility for radiation
processing
in
15572 E 1707-95 Guide for es tima ting uncertain ties dosimetry for radiation
processing
15573 E 1818-96 Practice for dosimetty in an electron-beam facility for radiation
processing at energies between 80 keV and 300 keV

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IS0 15561:1998(E)
@ IS0
AMEFKAN SOCIETY FOR TESTING AND MATERIALS
Designation: E 1401 - 96 An American National Standard
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted fr0f-n the Annual Book of ASTM Standards. Copyright ASTM
If not listed in the current combined index, will appear in the &xt edition.
Standard Practice for
Use of a Diehromate Dosimetry System’
This standard is issued under the fixed designation E 140 1; 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.
1. Scope
tionary statements are given in Note 6.
1 l 1 This practice covers the preparation, testing, and
2. Referenced Documents
procedure for using t,he acidic aqueous silver dichromate
2. I ASTM Standards:
dosimetry system to measure absorbed dose in water when
T9 12 Practice for Designing a Process for Cleaning
exposed to ionizing radiation. The system consists of a
Technical Glasses3 -
dosimeter and appropriate analvtical instrumentation. For
170 Terminology Relating to Radiation Measurements
simplicity, the system will be referred to as the dichromate
and Dosimetti
system. It is classified as a reference standard dosimetry
177 Practice for Use of the Terms Precision and Bias in
system (see Guide E 126 1).
1.2 This practice describes the spectrophotometric anal- ASTM Test Methods5
ysis procedures for the dichromate system. 178 Practice for Dealing with Outlying Observations5
275 Practice for Describing and Measuring Performance
1.3 This practice applies only to y-rays, x-rays, and high
energy electrons. of Ultraviolet, Visible and Near Infrared Spectropho-
1.4 This practice applies provided the following condi- tometer@
456 Terminology Relating to Quality and Statistics5
tions are satisfied:
666 Practice for Calculating Absorbed Dose from
1.4.1 The absorbed dose range is from 2 x 1 O3 to 5 x 10J
Gamma or X-Radiation4
GY
668 Practice for Application of Thermoluminescence
lO.4.2 The absorbed dose rate does not exceed 600 Gy/
Dosimetry (TLD) Systems for Determining Absorbed
pulse with a pulse repetition rate not to exceed 12.5 Hz, or
Dose in Radiation-Hardness Testing of Electronic
does not exceed an equivalent dose rate of 7.5 kGy/s from
Devices4
continuous sources ( 1).2
925 Practice for the Periodic Calibration of Narrow
1.4.3 For radionuclide gamma-ray sources, the initial
Band-Pass Spectrophotometers6
photon energy shall be greater than 0.6 MeV. For
958 Practice for Measuring Practical Spectral Band-
bremsstrahlung photons, the initial energy of the electrons
width of Ultraviolet-Visible Spectrophotometers6
used to produce the bremsstrahlung photons shall be equal to
1026 Practice for Using the Fricke Reference Standard
or greater than 2 MeV. For electron beams, the initial
Dosimetry System4
electron energy shall be greater than 8 MeV.
1205 Practice for Use of a Ceric-Cerous Sulfate
NOTE l-The lower energy limits given are appropriate for a
Dosimetry System4
cylindrical dosimeter ampoule of 12 mm diameter. Corrections for
126 1 Guide for Selection and Calibration of Dosimetry
displacement effects and dose gradient across the ampoule may be
Systems for Radiation Processing4
required for electron beams (2). The dichromate system may be used at
lower energies by employing thinner (in the beam direction) dosimeter 1400 Practice for Characterization and Performance of a
containers (see ICRU Report 35).
High-Dose Radiation Dosimetry Calibration Labora-
toti
1.4.4 The irradiation temperature of the dosimeter shall
1707 Guide for Estimating Uncertainties in Dosimetry
be above 0°C and should be below 80°C.
for Radiation Processing4
NOTE 2-The temperature coefficient of dosimeter response is 2.2 International Commission on Radiation Units and
known only in the range of 5” to 50°C (see 10.1 A). Use outside this range
Measurements (ICR U) Reports:’
is not recommended.
ICRU Report 14 Radiation Dosimetry: X-Rays and
Gamma Rays with Maximum Photon Energies Between
1.5 This standard does not purport to address all of the
0.6 and 60 MeV
safety concerns, if any, associated with its use. It is the
ICRU Report 33 Radiation Quantities and Units
responsibility of the user ofthis standard to establish appro-
ICRU Report 34 The Dosimetry of Pulsed Radiation
priate safety and health practices and determine the applica-
ICRU Report 35 Radiation Dosimetry: Electrons With
bility of regulatory limitations prior to use. Specific precau-
Initial Energies Between 1 and 50 MeV
i This practice is under the jurisdiction of ASTM Committee E-10 on Nuclear
3 Annual Book of ASTM Standards, Vol 15.02.
Technology and Applications and is the direct responsibility of Subcommittee
E 10.0 1 on Dosimetry for Radiation Processing. 4 Annual Book of ASTM Standards, Vol 12.02.
5 Annual Book of ASTM Standards, Vol 14.02.
Current edition approved June 10, 1996. Published August 1996. Originally
published as E 140 1 - 9 1, Last previous edition E 140 1 - 9 1. B Annual Book oJASTM Standards, VolO3.06.
2 The boldface numbers in parentheses refer to a list of references at the end of 7Available from the Commission on Radiation Units and Measurements
this practice. (ICRU), 79 10 Woodmont Ave., Bethesda, MD 208 14.

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IS0 15561 :1998(E) @ IS0
dence during irradiation that is approximately equal to
ICRU Report 37 Stopping Powers for Electrons and
-0.2 % per degree Celsius between 25 and 50°C. At temper-
Positrons
atures below 25 ”C, the dependence is smaller. The dosimeter
3. Terminology
response between 5 and 50°C is shown in Tgble 1, where the
response at a given temperature is tabulated relative to the
3.1 Definitions:
response at 25°C (4).
3.1. I absorbed dose (D), n-quantity of ionizing radiation
4.3.2 The data in Table 1 may be fitted with an appro-
energy imparted per unit mass of a specified material. The SI
priate formula for convenience of interpolation as follows:
unit of absorbed dose is the gray (Gy), where 1 gray is
equivalent to the absorption of 1 joule per kilogram of the
RT= b. + blTb2
(3)
specified material (1 Gy = 1 J/kg). The mathematical
where:
relationship is the quotient of dZ by dm, where d: is the
dosimeter response at temperature T relative to that at
R,=
mean incremental energy imparted by ionizing radiation to
25°C.
matter of incremental mass dm (see ICRU Report 33).
The fitted data is shown in Fig. 1‘
dz
4.4 No effect of ambient light (even direct sunlight) has
=-
D
(1)
dm
been observed on dichromate solutions in glass ampoules
(5)
3.1.1.1 Discussion-The discontinued unit for absorbed
4.5 For calibration with photons, the dichromate dosim-
dose is the rad (1 rad = 100 erg/g = 0.0 1 Gy). Absorbed dose
eter shall be irradiated under conditions that approximate
is sometimes referred to simply as dose.
electron equilibrium.
3.1.2 calibration ficility, n-combination of an ionizing
4.6 The absorbed dose in other materials irradiated under
radiation source and its associated instrumentation that
equivalent conditions may be calculated. Procedures for
provides a uniform and reproducible absorbed dose, or
making such calculations are given in Practices E 666 and
absorbed-dose rate traceable to national or international
E 668 and Guide E 126 1.
standards at a specified location and within a specific
4.7 The dosimeter response is dependent on the type and
material, and that may be used to derive the dosimetry
energy of the radiation employed. For example, the response
system ’s response function or calibration curve.
in high energy (10 MeV) electron beams is reported to be
a system used for determining
3.1.3 dosimetry system, n-
approximately 3 % lower than the response in cobalt-60
absorbed dose, consisting of dosimeters, measurement in-
radiation (2). The dosimeter shall be calibrated in a radiation
struments, and their associated reference standards, and
field of the same type and energy as that in which it is to be
procedures for the system ’s use.
used.
3.1.4 measurement quality assurance plan, n-a docu-
mented program for the measurement process that ensures
5. Interferences
on a continuing basis that the overall uncertainty meets the
requirements of the specific application. This plan requires 5.1 The dichromate dosimetric solution response is sensi-
traceability to, and consistency with, nationally or intema- tive to impurities, particularly organic impurities. Even in
tionally recognized standards. trace quantities, impurities can cause a detectable change in
3.1.5 net absorbance, (AA ), n-change in measured op- the observed response (5). For high accuracy results, organic
tical absorbance at a selected wavelength determined as the
materials shall not be used for any component in contact
absolute difference between the pre-irradiation absorbance,
with the solution. The effect of trace impurities may be
Ao, and the post-irradiation absorbance, A, as follows: minimized by pre-irradiation of the bulk dichromate solu-
tion (see Ref (5) and 8.2).
AA = IA --A,1
(2)
5.2 Undesirable chemical changes in the dosimetric solu-
3.1.6 reference standard dosimeter, n-a dosimeter of tion can occur if care is not taken during flame-sealing of the
high metrological quality, used as a standard to provide ampoules (see 8.4).
measurements traceable to and consistent with measure-
ments made using primary standard dosimeters.
6. Apparatus
NOTE 3-For other terms, see Terminology E 170.
6.1 High-Precision Spectrophotometer-For the analysis
of the dosimetric solution, use a high-precision spectropho-
4. Significance and Use
tometer capable of measuring absorbance values up to 2 with
4.1 The dichromate system provides a reliable means for
an uncertainty of no more than rtl % in the region of 350 to
measuring absorbed dose in water. It is based on a process of
440 nm, Use a quartz cuvette with 5 or 10 mm path length
reduction of dichromate ions to chromic ions in acidic
for spectrophotometric measurements of the solution., The
aqueous solution by ionizing radiation.
4.2 The dosimeter is a solution containing silver and
dichromate ions in perchloric acid in an appropriate con-
tainer such as a flame-sealed glass ampoule. The solution
indicates absorbed dose by a change (decrease) in optical
absorbance at a specified wavelength(s) (3). A calibrated
spectrophotometer is used to measure the absorbance.
4.3 Efect of Irradiation Temperature:
4.3.1 The dosimeter response has a temperature depen-
2
2

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ISO15561:1998(E)
El401
suppliers. Such water Iabelled HPLC (high pressure liquid chromatog-
raphy) grade is usually suffkiently free of organic impurities to be used
in this practice.
8. Preparation of Dosimeters
8.1 The recommended concentrations for the dichromate
dosimeter to measure absorbed doses from about 2 to 10
g 0.96 kGy (hereafter called the low-range dosimeter) are 0.5 x
:
.-
10m3 mol dma3 silver dichromate (Ag,Cr,O,) in 0.1 mol
5
dmw3 aqueous perchloric acid (6). For measurement of
z
absorbed doses from about 5 to 50 kGy (using the dosimeter
0 96
hereafter called the high-range dosimeter), the recommended
concentrations are 0.5 x 10e3 mol dm-’ silver dichromate
and 2.0 X low3 mol drnw3 potassium dichromate (KZCr207)
in 0.1 mol dmV3 aqueous perchloric acid (5). Air saturate
0.94-J- , 1 r 1 I I
5 15 25 35 45
both solutions before use. Silver dichromate dissolves slowly
lrradialion Temperature, OC
and normally requires at least 18 h to dissolve completely.
FIG. 1 Relative Response of Dichromate Bosimeter as a Func-
For the high range dosimeter, it is preferable to dissolve the
tion of Irradiation Temperature. A Fit of the Data Using Eq 3 Yields
silver dichromate before adding the potassium dichromate.
Fit Parameters as Follows: b, = 1.021; b, = -6.259 x 100~; b, =
1.806.
NOTE 6: Precaution-Concentrated perchloric acid is a strong oxi-
dizer and dichromate salts are skin irritants. Appropriate precautions
should be exercised in handling these materials.
cuvette capacity must be small enough to allow it to be
NOTE 7-Dichromate dosimeters of other formulations have been
thoroughly rinsed by the dosimeter solution and still leave an
described (7,8).
adequate amount of that solution to fill the cuvette to the
8.2 If appropriate, irradiate the bulk solution to minimize
appropriate level for the absorbance measurement. For
the effects of impurities.
dosimeter ampoules of 2 mL or less, this may require the use
8.2.1 The exact dose is not critical, but a minimum dose
of micro-capacity cuvettes. Other solution handling tech-
of 1.0 kGy is recommended (5).
niques, such as the use of micro-capacity flow cells, may be
8.2.2 Choose the size of the container for this bulk
employed provided precautions are taken to avoid cross-
solution so that the dose delivered to any part of the solution
contamination. Control the temperature of the dosimetric
is 1.1 t 0.1 kGy.
solution during measurement at 25 $- 1°C. If this is not
8.2.3 Mix the solution thoroughly after irradiation.
possible, determine the solution temperature during the
8.3 Rinse the dosimeter ampoules or other containers as
spectrophotometric analysis and correct the measured
prepared in 6.2 at least once with the dosimeter solution
absorbance to 25OC. The temperature coefficient during
before filling them for irradiation.
measurement is -0.1 % per degree Celsius within the range
8.4 E
...