ISO 15567:1998

INTERNATIONAL IS0
15567
STANDARD
First edition
1998-12-15
Practice for dosimetry in an X-ray
(bremsstrahlung) facility for radiation
processing
Pratique de la dosimktrie dans une installation de traitement de produits
alimentaires par des rayons X (Bremsstrahlung)
Reference number
IS0 15567: 1998(E)

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IS0 15567:1998(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 lnternationa Standards adopted by the technical committees are circulated to the member bodies for votin .
g
res approval by at least 75 % of the me
Publication as an I nternational Standard requi ‘mber bodies casting a vote.
International Standard IS0 15567 was prepared by the American Society for Testing and Materials (ASTM)
Subcommittee E1O.O1 (as E 1608-94) and was adopted, under a special “fast-track procedure ”, by Technical
Committee ISOKC 85, Nuclear energy, in parallel with its approval by the IS0 member bodies.
A new ISO/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 15567 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
E 1261-94
15556 Guide for selection and calibration of dosimetry systems for
radiation processing
15557 E 1275-93 Practice for use of a radiochromic film dosimetty system
15558 E 1276-96 Practice for use of a polymethylmethacrylate dosimetry system
15559 E 1310-94 Practice for use of a radiochromic optical waveguide dosimetry
system
15560 E 1400-95a Practice for characterization and performance of a high-dose
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 s #pecified, no pa rt of this publication may be reproduced or utilized in any form or by any means, electronic
permission
or mechanical, including photocopying and microfilm, without 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
ii

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as0 IS0 15567:1998(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
15565 E 1540-93 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
E 1631-96 Practice for use of calorimetric dosimetry systems for electron
15568
beam dose measurements and dosimeter calibrations
15569 E 1649-94 Practice for dosimetry in an electron-beam facility for radiation
processing at energies between 300 keV and 25 MeV
15570 E 1650-94 Practice for use of cellulose acetate dosimetty system
15571 E 1702-95 Practice for dosimetry in a gamma irradiation facility for radiation
processing
E 1707-95 Guide for estimating uncertainties in dosimetry for radiation
15572
processing
15573 E 1818-96 Practice for dosimetry in an electron-beam facility for radiation
processing at energies between 80 keV and 300 keV
For the purposes of this International Standard, the following amendments to the ASTM text apply.
Page I, subclause 1.3
Replace subclause 1.3 by the following.
1.3 Dosimetry is only one component of a total quality assurance program for an irradiation facility. Other
controls besides dosimetry may be required for specific applications such as medical device sterilization and
food preservation.
1.4 For the irradiation of food and the radiation sterilization of health care products, other specific IS0
standards exist. For food irradiation, see IS0 15562:1998, Practice for dosimetry in electron and
bremsstrahlung irradiation facilities for food processing (ASTM Practice E 1431). For the radiation sterilization
of health care products, see IS0 11137:1995, Sterilization of health care products - Requirements for
areas covered by IS0 11137, that standard
validation and routine control - Radiation sterilization. In those
takes precedence.
Page I, subclause 1.4
Renumber this subclause as 1.5.
. . .
Ill

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IS0 15567:1998(E)
0 IS0
AMERICAN SOCIETY FOR TESTING AND MATERIALS
Designation: E 1608 - 94
1916 Race St Philadelphia, Pa 19103
4/b
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
If not listed in the current combined index, will appear i? the next edition.
Standard Practice for
Dosimetry in an X-Ray (Bremsstrahlung) Facility for Radiation
Processing’
This standard is issued under the fixed designation E 1608; 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 (f) indicates an editorial change since the last revision or reapproval.
1. Scope E 1205 Practice for Use of a Ceric-Cerous Sulfate
Dosimetry System2
1.1 This practice covers dosimetric procedures to be
E 1261 Guide for the Selection and Application of
followed in facility characterization, process qualification,
Dosimetry Systems for Radiation Processing of Food2
and routine processing using X-rays (bremsstrahlung) to
E 1275 Practice for Use of a Radiochromic Film Dosim-
ensure that the entire product has been treated within an
etry System2
acceptable range of absorbed doses. Other procedures related
E 1276 Practice for Use of a Polymethylmethacrylate Do-
to facility characterization, process qualification, and routine
simetry System2
processing that may influence absorbed dose in the product
E 13 10 Practice for Use of a Radiochromic Optical
are also discussed. The establishment of effective or regula-
Waveguide Dosimetry System2
tory dose and X-ray energy limits are not within the scope of
E 1400 Practice for Characterization and Performance of a
this practice.
High-Dose Gamma-Radiation Dosimetry Calibration
1.2 In contrast to monoenergetic gamma rays, the
Laboratory2
bremsstrahlung energy spectrum extends from low values up
E 1401 Practice for Use of a Dichromate Dosimetry
to the maximum energy of the electrons incident on the
System2
X-ray target (see Section 5 and the Appendix).
E 143 1 Practice for Dosimetry in Electron and Brems-
1.3 Dosimetry is only one component of a total quality
strahlung Irradiation Facilities for Food Processing2
assurance program for an irradiation facility. Other controls
E 1538 Practice for Use of the Ethanol-Chlorobenzene
besides dosimetry may be required for specific applications
Dosimetry System2
such as medical device sterilization and food preservation
E. 1539 Guide for Use of Radiation-Sensitive Indicators2
(see Sections 8, 9, and 10 and Note 8).
E 1540 Practice for Use of a Radiochromic Liquid
NOTE l-For guidance in the selection, calibration, and use of Dosimetry System2
specific dosimeters and interpretation of absorbed dose in the product
E 1607 Practice for Use of the Alanine-EPR Dosimetry
from dose measurements, see the documents listed in 2.1 and 2.2.
System2
NOTE 2-Bremsstrahlung characteristics are similar to gamma rays
2.2 ZCRU Reports:3
from radioactive isotopes. See Practice E 1204 for the applications of
Report 14 Radiation Dosimetry: X Rays and Gamma
dosimetry in the characterization and operation of gamma-ray irradia-
Rays with Maximum Photon Energies Between 0.6 and
tion facilities. For information concerning electron beam irradiation
technology and dosimetry, see Practice E 143 1. 50 MeV
Report 33 Radiation Quantities and Units
1.4 This standard does not purport to address all of the
Report 35 Radiation Dosimetry: Electron Beams with
safety concerns, ty any, associated with its use. It is the
Energies Between 1 and 50 MeV
responsibility of the user of this standard to establish appro-
Report 37Stopping Powers for Electrons and Positrons
priate safety and health practices and determine the applica-
bility ofregulatory limitations prior to use.
3. Terminology
3.1 Definitions-Definitions of terms used in this practice
2. Referenced Documents
may be found in Terminology E 170 and ICRU Report 33.
3.2 Descriptions of Terms Spectjk to This Standard-
2.1 ASTM Standards:
Definitions of some terms specific to this practice are listed
E 170 Terminology Relating to Radiation Measurements
below.
and Dosimetry2
3.21 absorbed dose, D-the quotient of de by dm, where
E 1026 Practice for Using the Fricke Reference Standard
de is the mean energy imparted by ionizing radiation to
Dosimetry System2
matter of mass dm (see ICRU Report 33):
E 1204 Practice for Dosimetry in Gamma Irradiation
Facilities for Food Processing2
D = deldm
The special name of the unit for absorbed dose in the
International System of Units (SI) is the gray (Gy).
r This practice is under the jurisdiction of ASTM Committee E-10 on Nuclear
Technology and Applications and is the direct responsibility of Subcommittee
E 10.0 1 on Dosimetry for Radiation Processing.
Current edition approved April 15, 1994. Published August 1994. 3 Available from International Commission on Radiation Units and Measure-
2 Annual Book o/ASTM Standards, Vol 12.02. ments, 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814.
1

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IS0 15567:1998(E) 0 IS0
1 Gy= I J kg-’
mented program for the measurement process that quantifies
the total uncertainty of the measurements (both random and
3.2.1.1 Discussion-The special unit for absorbed dose
systematic error components). This plan shall demonstrate
was formerly the rad.
traceability to national standards and shall‘ show that the
1 rad = lo-* J kg-’
total uncertainty meets the requirements of the specific
1 rad = lo-* Gy application.
3.2.12 traceability-an unbroken chain of calibrations
1 Mrad = 10 kGy
leading to documented assurance that the dose reading of a
3.2.2 absorbed dose enhancement-the increase (de-
dosimetersystem has been derived from a certified reference
crease) in the absorbed dose, as compared to the equilibrium
material, national or international standard.
dose, at a point in the material of interest. This will occur
3.2.13 X rays-the common name for the short-wave-
near an interface between materials with different atomic
length electromagnetic radiation emitted by high-energy
: -
numbers.
electrons when they are accelerated, decelerated, or deflected
3.2.3 bremsstrahlung-broad-spectrum electromagnetic
by strong electric or magnetic fields. The term includes both
radiation emitted when an energetic electron is influenced by
bremsstrahlung from nuclear collisions and the characteristic
a magnetic or strong electric field, such as that in the vicinity
monoenergetic radiation emitted when atomic electrons
of an atomic nucleus.
make transitions to more tightly bound states.
3.2.3.1 Discussion-When a beta particle (electron)
3.2.14 X-ray converter-a device for generating X rays
passes close to a nucleus, the strong attractive coulomb force
(bremsstrahlung) from an electron beam, consisting of a
causes the beta particle to deviate sharply from its original
target, means for cooling the target, and a supporting
path. The change in direction is due to radial acceleration,
structure.
and in accordance with classical theory the beta particle loses
3.2.15 X-ray target-the X-ray converter that is struck by
energy by electromagnetic radiation at a rate proportional to
the electron beam. It is usually made of metal with a high
the square of the acceleration. This means that the
atomic number, high melting temperature, and high thermal
bremsstrahlung photons have a continuous energy distribu-
conductivity.
tion that ranges downward from a theoretical maximum
equal to the kinetic energy of the beta particle. Practically,
4. Significance and Use
bremsstrahlung is produced when an electron beam strikes
4.1 A variety of products and materials may be irradiated
any material (converter). The bremsstrahlung spectrum de-
with X rays to modify their characteristics and improve the
pends on the electron energy, converter material, and its
economic value. Examples are single-use medical devices
thickness.
(sterilization), agricultural commodities (preservation),. and
3.2.4 calibration curve-the graphical or mathematical
various polymeric products (material modification). Dosim-
relationship between the response of a dosimeter and the
etry requirements for X-ray processing may vary depending
absorbed dose for a given dosimetry system. This is also
on the type and end use of the product.
referred to as the dosimetry system response function.
3.2.5 dose uniformity ratio-the ratio of the maximum to
NOTE 3-Dosimetry is required for regulated irradiation processes,
minimum absorbed dose within an irradiation container.
such as the sterilization of medical devices and the preservation of food,
3.2.5.1 Discussion-It is a measure of the degree of because the results may affect the health of the consumer. It is less
important for other industrial processes, such as polymer modification,
uniformity of the absorbed dose. This concept is also referred
which can be evaluated by changes in the physical properties of the
to as the max/min dose ratio.
irradiated materials. Nevertheless, routine dosimetry may be used to
3.2.6 dosimeter (dose meter)-a device for measuring
monitor the reproducibility of the treatment process.
radiation-induced signals that can be related to absorbed
4.2 As a means of (quality) control of an irradiation
dose (or energy deposited) by radiation in materials and is
calibrated in terms of the appropriate quantities and units. process, dosimeters are used to relate their calibrated re-
3.2.7 dosimetry system- a system used for determining sponse to radiation exposure to the absorbed dose in the
absorbed dose, consisting of dosimeters, measurement in- material or product being irradiated (see Section 7).
4.3 Radiation processing specifications usually include a
strumentation, the calibration curve, reference standards,
pair of absorbed-dose limits: a minimum value to ensure the
and procedures for the system ’s use.
3.2.8 electron energy-the kinetic energy of an electron intended beneficial effect and a maximum value to avoid
that is usually given in units of electron volts (eV), product degradation. For a given application, one or both of
kiloelectron volts (keV), or megaelectron volts (MeV). these values may be prescribed by process specifications or
3.2.9 electron energy spectrum-the frequency distribu- regulations. Knowledge of the dose distribution within the
tion of electrons as a function of energy. The energy irradiated material is essential to meet these requirements.
4.4 Several critical parameters must be controlled to
spectrum of the electrons incident on the converter depends
on the type of electron accelerator and the beam dispersion obtain reproducible dose distributions in the processed
system being used. materials. The processing rate and dose distribution depend
3.2.10 equilibrium absorbed dose-the absorbed dose on the X-ray intensity, photon energy spectrum, spatial
value that exists in a material at a minimum distance from distribution of the radiation field, conveyor speed, and
any interface with another material, with this distance being product configuration (see Sections 5 and 10 and the
Appendix).
greater than the range of the maximum energy electrons
generated by the incident photons. 4.5 Before an irradiation process can be used, it must be
3.2.11 measurement quality assurance plan-a docu- qualified to determine its effectiveness in delivering known,
2
2

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IS0 15567:1998(E)
@ IS0
Practices E 1026, E 1204, E 1205, E 1275, E 1276, E 13 10,
controllable doses. This involves testing the process equip-
ment, calibrating the measuring instruments and dosimetry E 1400, E 1401, E 1431, E 1538, E 1540, and E 1607,
system, and demonstrating the ability of the process to Guides E 1261 and E 1539, and ICRU Reports 14, 33, 35,
deliver the desired dose distributions in a reliable and and 37).
reproducible. manner (see Sections 8 and 9).
NOTE 4-Dosimeters consisting mainly of water or hydrocarbon
4.6 To ensure consistent dose delivery in a qualified
materials are suitable for both gamma rays and high-energy X rays.
Some exceptions are dosimeters containing substantial amounts of
irradiation process, routine process control requires proce-
material with high atomic numbers. These may be especially sensitive to
dures for product handling before and after the treatment,
the low-energy photons in the bremsstrahlung spectrum.
prescribed orientation of the products during irradiation,
NOTE S-The X-ray dose rate may be higher than that of gamma
monitoring of critical process parameters, routine product
rays used for radiation processing, especially in products passing near the
dosimetry, and documentation of the required activities and
X-ray converter. The dose-rate dependence of the dosimeters should be
functions (see Sections 10 and 11).
considered in their calibration procedure (see Refs 6 and 7).
7.2 Dosimeter Calibration:
5. Radiation Source Characteristics
7.2.1 A dosimetry system shall be calibrated prior to use
5.1 A high-energy X-ray (bremsstrahlung) generator emits
in accordance with a documented procedure that specifies
short-wavelength electromagnetic radiation, which is analo-
details of the calibration process and quality assurance
gous to nuclear gamma radiation. Although their effects on
requirements. The system shall also be calibrated at periodic
irradiated materials are generally similar, these kinds of
intervals to ensure that the accuracy of the absorbed-dose
radiation differ in their energy spectra, angular distributions,
measurement is maintained within required limits.
and dose rates.
7.2.2 The instruments used in the analysis of the dosime-
5.2 The physical characteristics of the X-ray field depend
ters shall be calibrated at periodic intervals using appropriate
on the design of the X-ray converter and the parameters of
standards traceable to national standards.
the electron beam striking the target, that is, the electron
7.2.3 Each batch of dosimeters shall be calibrated by an
energy spectrum, average electron beam current, and beam
irradiation facility that has an absorbed dose rate traceable to
current distribution on the target.
national standards and comparable to the dose rate in the
5.3 These aspects of an X-ray source and its suitability for
production facility. The irradiation facility should meet the
radiation processing are reviewed in more detail in the
requirements specified in Practice E 1400. Alternatively,
Appendix.
each batch may be calibrated against a standard dosimeter
under the actual conditions of use in the production irradia-
6. Irradiation Facilities
tion facility.
6.1 Facility Components-An X-ray irradiation facility
8. Installation Qualification
includes a high-energy, high-power electron accelerator with
X-ray converter, product conveyor, radiation shield with
8.1 The purpose of dosimetry in qualifying an X-ray
personnel safety system, product staging, loading and storage
facility is to establish baseline data for monitoring the
areas, auxiliary equipment for power, cooling, ventilation,
effectiveness, predictability, and reproducibility of the irradi-
etc., an equipment control room, laboratory for dosimetry,
ation process throughout a typical range of operating param-
and product testing, and personnel offices. The design shall
eters. Dosimetry shall be used for the following purposes:
conform to applicable regulations and guidelines (see Refs 1
8.1.1 To establish relationships between absorbed dose in
and 2).
a reproducible geometry and operating parameters.
6.2 Product Handling System-The penetrating quality of
8.1.2 To characterize the stability of dose when these
high-energy X rays permits the treatment of large containers
parameters fluctuate statistically and through normal opera-
or full pallet loads of products. The container size for
tions.
optimum photon power utilization and dose uniformity
8.1.3 To measure absorbed dose distributions in reference
depends on the maximum energy and product density. The
materials.
narrow angular distribution of the radiation favors the use of
8.2 Equipment Documentation-Documentation shall
continuously moving conveyors rather than shuffle-dwell
exist describing the equipment, any modifications, and its
systems to enhance dose uniformity.
operation. This information shall be retained for the life of
6.3 Irradiation System-The configuration of the X-ray
the facility. It shall include the following:
converter, the beam current distribution on the target, and
8.2.1 The layout of the facility showing the locations of
the penetrating quality of the radiation, and the size, shape,
the major components;
and density of the product load affect the dose uniformity
8.2.2 The descriptions, specifications, and characteristics
ratio (see Refs 3-5).
of the electron accelerator, the X-ray converter, the product
conveyor, the control system, and all other auxiliary equip
7. Dosimetry Systems
ment and instrumentation;
7.1 Dosimeter Selection-The ASTM and ICRU docu- 8.2.3 The testing, calibrating, and operating procedures
ments listed in 2.1 and 2.2 provide detailed information on for all of the equipment and instrumentation, including the
the selection and use of high-dose dosimeter systems for dosimetry system;
8.2.4 Identification of the instrumentation used to con-
gamma-ray (photon) and electron-beam irradiation facilities.
trol, monitor, and record the critical process parameters that
Many of these dosimetry systems are also applicable for
affect the absorbed dose in the irradiated products.
high-energy X rays since their radiation responses are
relatively insensitive to the photon or electron energies (see 8.3 Equipment Testing and Calibration-The first phase
3
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@ IS0
IS0 15567:1998(E)
10. Routine Processing
of qualifying an irradiation facility is to determine that the
processing equipment performs according to its specifica-
10.1 Process Monitoring-All critical process parameters
tions. This includes the accelerator and X-ray converter,
that can affect the absorbed dose distribution must be
product conveyor, control system and its software, and other
controlled and monitored during all routine processing. The
auxiliary equipment and instrumentation. Calibration of the
tolerance limits on these parameters must be determined and
equipment, instrumentation, and dosimetry system is also
the treatment process aborted if excessive variations occur.
essential. Special emphasis must be given to the critical
Measurements of these critical parameters should be made
parameters that affect the dose distribution in the irradiated
and also recorded at regular intervals to prove the continuity
products. These include the electron energy, electron beam
of the process (see 4.4).
current, beam scanning amplitude, and conveyor speed.
10.2 Routine Dosimetry-It is not necessary to have
8.4 Irradiator Characterization-The second phase is to
dosimeters on every product unit, but they should be placed
show that the irradiation process can be accomplished within
at the beginning and the end of a production run to confirm
the specified tolerances under prescribed operating condi-
the validity of the irradiation process. For long runs, dosim-
tions and that the results are reproducible. Reference mate-
eters should also be placed near the middle of the run and at
rial of product can be used for this purpose. The dose
other intervals as appropriate.
distribution within the reference material or product should
11. Certification
be determined by detailed dose mapping. The effects of small
11.1 Process Control-All equipment functions and per-
variations in the critical process parameters should be
sonnel activities that ensure the effectiveness of the irradia-
assessed and recorded.
tion process are components of the process control program.
8.5 Measurement Quality Assurance Plan-Proper mea-
These include product handling procedures before and after
surement procedures, with appropriate statistical controls
irradiation, proper loading of the product conveyor, moni-
and documentation, shall be used to ensure that the equip-
toring of the critical process parameters, and routine product
ment works properly and that the treatment process delivers
dosimetry.
the required doses according to specifications.
11.2 Documentation-All aspects of the irradiation pro-
cess that can affect its validity should be covered by written
procedures. Installation qualification and process qualifica-
9. Process Qualification
tion should be accomplished according to plan and all of the
9.1 Process Parameters-For each product to be treated
results recorded. Routine operations and dosimetry data
in the irradiation facility, there will usually be a minimum
should be recorded and correlated with product records.
dose to obtain the desired effect and a maximum dose that
11.3 Documentation should be reviewed by authorized
the product can tolerate without degradation in quality.
personnel and maintained for inspection.
These dose limits may have to be determined experimen-
12. Precision and Bias
tally. The equipment parameters to achieve the required
doses must also be determined. 12.1 Records and reports should include estimates of the
9.2 Absorbed Dose Mapping-The dose distribution measurement uncertainty of absorbed dose that include both
within the product package and throughout the product precision and bias at a specified confidence level (see Guide
container or pallet load must be measured to find the E 1261).
locations of the minimum and maximum doses. The rela-
12.2 The critical parameters for the irradiation process
tionship of these doses to that obtained at a conveniently
should take into account the level of uncertainty of the
accessible point on the outside of the product or container
dosimetry system to ensure delivery of the required dose.
may also be determined for use in routine processing. The
12.3 The calibration of the dosimeters should be traceable
reproducibility of these doses at the minimum, maximum,
to national standards and should be conducted at regular
and monitoring points should be evaluated. The effects of
intervals (see Guide E 126 1).
variations in the critical process parameters must also be
NOTE &Additional information on regulations and guidelines for
evaluated.
radiation processing can be found in Refs 8-20.
13. Keywords
NOTE 6-Monitoring of operating parameters alone may not be
adequate for some radiation processes (for example, sterilization of 13.1 absorbed dose; bremsstrahlung; dose distribution;
medical products and preservation of food). Dosimetry is required
dose mapping; dosimeter; dosimetric procedures; dosimetry;
during routine product processing for these situations.
electron accelerator; electron beam; facility characterization;
NOTE 7-In conjunction with dose distribution measurements, it is
ionizing radiation; irradiator characterization; photon; radi-
usually necessary to conduct testing of the product materials to ensure
ation; radiation dosimetry; radiation facility; radiation pro-
compatibility with the X-ray treatment. It is recommended that this
cessing; X ray; X-ray processing; X-ray target; X-ray
testing be performed at doses larger than the maximum absorbed dose
utilization
attained during routine processing.

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IS0 15567:1998(E)
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APPENDIX
Nonmandatory Information
Xl. X-RAY (BREMSSTRAHLUNG) CHARACTERISTICS
Xl. 1 X-Ray Proce&ing-The physical properties of X cooling system (1, 45). The total thickness of the target
assembly plus the cooling channel should be slightly greater
rays (bremsstrahlung) are well known, and the use of this
type of radiation for material processing has been studied than the maximum electron range in order to avoid irradi-
extensively (21). Some important characteristics of this ating the products with primary electrons.
technology are described below, and more detailed informa- X 1.4 Converter an
...