ISO/ASTM 51649:2015

Practice for dosimetry in an electron beam facility for radiation processing at energies between 300 keV and 25 MeV

ISO/ASTM 51649:2015 outlines dosimetric procedures to be followed in installation qualification (IQ), operational qualification (OQ) and performance qualifications (PQ), and routine processing at electron beam facilities. The electron beam energy range covered in this practice is between 300 keV and 25 MeV, although there are some discussions for other energies. Dosimetry is only one component of a total quality assurance program for adherence to good manufacturing practices used in radiation processing applications. Other measures besides dosimetry may be required for specific applications such as health care product sterilization and food preservation. ISO/ASTM 51649:2015 is one of a set of standards that provides recommendations for properly implementing and utilizing dosimetry in radiation processing. It is intended to be read in conjunction with ISO/ASTM 52628, "Practice for Dosimetry in Radiation Processing".

Pratique de la dosimétrie dans une installation de traitement par irradiation utilisant un faisceau d'électrons d'énergies comprises entre 300 keV et 25 MeV

General Information

• Status: Published
• Publication Date: 16-Mar-2015
• 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: 9093 - International Standard confirmed
• Completion Date: 04-Jun-2020

Relations

• Revises: ISO/ASTM 51649:2005 - Practice for dosimetry in an electron beam facility for radiation processing at energies between 300 keV and 25 MeV
• Effective Date: 07-Jun-2014

Standards Content (Sample)

INTERNATIONAL ISO/ASTM
STANDARD 51649
Third edition
2015-03-15
Practice for dosimetry in an electron
beam facility for radiation processing at
energies between 300 keV and 25 MeV
Pratique de la dosimétrie dans une installation de traitement par
irradiation utilisant un faisceau d’électrons d’énergies comprises
entre 300 keV et 25 MeV
Reference number
ISO/ASTM 51649:2015(E)
© ISO/ASTM International 2015

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ISO/ASTM 51649:2015(E)
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ISO/ASTM 51649:2015(E)
Contents Page
1 Scope. 1
2 Referenced documents. 1
3 Terminology. 2
4 Significance and use. 6
5 Radiation source characteristics. 6
6 Documentation. 6
7 Dosimetry system selection and calibration. 6
8 Installation qualification. 7
9 Operational qualification. 7
10 Performance qualification. 8
11 Routine process control. 9
12 Certification. 10
13 Measurement uncertainty. 10
14 Keywords. 10
Annexes. 11
Figure1 Exampleshowingpulsebeamcurrent(I ),averagebeamcurrent(I ),(pulsewidth
pulse avg
(W) and repetition rate (f) for a pulsed accelerator. 3
Figure 2 Diagram showing beam length and beam width for a scanned beam using a conveyor
system. 3
Figure 3 Example of electron-beam dose distribution along the scan direction, where the beam
width is specified at a defined fractional level f of the average maximum dose D . 4
max
Figure 4 A typical depth-dose distribution for an electron beam in a homogeneous material. 4
Figure 5 Typical pulse current waveform from an S-Band linear accelerator. 5
Figure A2.1 Calculated depth-dose distributions in various homogeneous polymers for normally
incident 5.0 MeV (monoenergetic) electrons using the Program ITS3 (19, 21). 13
FigureA2.2 Calculateddepth-dosedistributionsinvarioushomogeneousmaterialsfornormally
incident 5.0 MeV (monoenergetic) electrons using the Program ITS3 (19, 21). 14
FigureA2.3 Calculateddepth-dosedistributionsinpolystyrenefornormallyincidentelectronsat
monoenergetic energies from 300 to 1000 keV using the Program ITS3 (19, 20). 15
FigureA2.4 Calculateddepth-dosedistributionsinpolystyrenefornormallyincidentelectronsat
monoenergetic energies from 1.0 to 5.0 MeV using the program ITS3 (19, 20). 16
FigureA2.5 Calculateddepth-dosedistributionsinpolystyrenefornormallyincidentelectronsat
monoenergetic energies from 5.0 to 12.0 MeV using the program ITS3 (19, 20). 17
FigureA2.6 Calculated depth-dose distributions inAl andTa for normally incident electrons at a
monoenergetic energy of 25 MeV using the program ITS3 (19, 24). 18
Figure A2.7 Superposition of calculated depth-dose distributions for aluminum irradiated with
5-MeV monoenergetic electrons from both sides with different thicknesses (T) and from one
side using experimental data presented in Refs (18 and 25) (see Notes A2.2-A2.4). 18
Figure A2.8 Calculated correlations between incident electron beam energy and optimum
thickness R , half-value depth R , half-entrance depth R , and practical range R for
opt 50 50e p
polystyrene using data from Fig. A2.3 and Fig. A2.4 (see Table A4.1). 19
Figure A2.9 Calculated correlations between incident electron beam energy and optimum
thickness R , half-value depth R , half-entrance depth R , and practical range R , for
opt 50 50e p
polystyrene using data from Figs. A2.4 and A2.5 (see Table A4.1). 19
FigureA2.10 Measureddepth-dosedistributionsfornominal10MeVelectronbeamsincidenton
polystyrene for two electron beam facilities (26, 27). 20
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ISO/ASTM 51649:2015(E)
Figure A2.11 Depth-dose distributions in stacks of cellulose acetate films backed with wood,
aluminum, and iron for incident electrons with 400 keV energy (30). 21
Figure A2.12 Depth-dose distributions with 2 MeV electrons incident on polystyrene absorbers
at various angles from the normal direction (31). 21
Figure A3.1 Stack measurement device. 22
Figure A3.2 Wedge measurement device. 23
Figure A5.1 Example of dose as function of average beam current (I), conveyor speed (V) and
beam width (W ). 26
b
Figure A7.1 Different scan characteristics used for electron beams. 28
Figure A7.2 Example of a scanned and pulsed beam with parameters needed for beam spot
calculations indicated. 28
FigureA8.1 Example of isodose curves obtained by irradiation at a 10-MeV electron accelerator
3
of expanded polystyrene foam (specific density approximately 0.1 g/cm ). 29
FigureA10.1 Electron energy deposition at the entrance surface of a polystyrene absorber as a
functionofincidentelectronenergyfrom0.3MeVto12MeVcorrespondingtotheMonteCarlo
calculated data shown in Figs. A2.3-A2.5. 31
FigureA10.2 Electron energy deposition at the entrance surface of a polystyrene absorber as a
function of incident electron energy from 0.3 MeV to 2.0 MeV corresponding to the Monte
Carlo calculated data shown in Fig. A2.3 and Fig. A2.4. 32
Table . 4
TableA2.1 Keyparametersformeasureddepth-dosedistributioncurvespresentedinFig.A2.10. 20
Table A3.1 Some relevant properties of common reference materials. 22
TableA4.1 Half-valuedepthR ,half-entrancedepthR ,optimumthicknessR andpractical
50 50e opt
rangeR inpolystyreneformonoenergeticelectronenergiesEfrom0.3to12MeVderivedfrom
p
Monte Carlo calculations (20). 25
TableA4.2 Half-value depthR , practical rangeR and extrapolated rangeR in aluminum for
50 p ex
monoenergetic.electronenergyEfrom2.5to25MeVderivedfromMonteCarlocalculations. (2525)
Table A10.1 Electron energy deposition at the entrance surface of a polystyrene absorber as a
function of incident electron energy from 0.3 MeV to 12 MeV corresponding to the calculated
curves shown in Figs. A2.3-A2.5. 32
Table A11.1 Needs for requalification following changes of an electron beam facility. 33
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ISO/ASTM 51649:2015(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 Committee E61, 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 51649 was developed by ASTM Committee E61, Radiation Processing,
through Subcommittee E61.03, Dosimetry Application, and by Technical Committee ISO/TC 85, Nuclear
energy, nuclear technologies and radiological protection.
This third edition cancels and replaces the second edition (ISO/ASTM 51649:2005), which has been
technically revised.
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ISO/ASTM 51649:2015(E)
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ISO/ASTM 51649:2015(E)
An American National Standard
Standard Practice for
Dosimetry in an Electron Beam Facility for Radiation
1
Processing at Energies Between 300 keV and 25 MeV
This standard is issued under the fixed designation ISO/ASTM 51649; 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 priate safety and health practices and determine the applica-
bility of regulatory requirements prior to use.
1.1 This practice outlines dosimetric procedures to be fol-
lowed in installation qualification (IQ), operational qualifica-
2. Referenced documents
tion (OQ) and performance qualifications (PQ), and routine
2
2.1 ASTM Standards:
processing at electron beam facilities.
E170Terminology Relating to Radiation Measurements and
1.2 The electron beam energy range covered in this practice
Dosimetry
is between 300 keV and 25 MeV, although there are some
E2232Guide for Selection and Use of Mathematical Meth-
discussions for other energies.
ods for Calculating Absorbed Dose in Radiation Process-
1.3 Dosimetry is only one component of a total quality
ing Applications
assurance program for adherence to good manufacturing prac- E2303Guide for Absorbed-Dose Mapping in Radiation
tices used in radiation processing applications. Other measures
Processing Facilities
besides dosimetry may be required for specific applications F1355GuideforIrradiationofFreshAgriculturalProduceas
such as health care product sterilization and food preservation.
a Phytosanitary Treatment
F1356PracticeforIrradiationofFreshandFrozenRedMeat
1.4 Specific standards exist for the radiation sterilization of
and Poultry to Control Pathogens and Other Microorgan-
health care products and the irradiation of food. For the
isms
radiation sterilization of health care products, see ISO 11137-1
F1736Guide for Irradiation of Finfish and Aquatic Inverte-
(Requirements) and ISO 11137-3 (Guidance on dosimetric
brates Used as Food to Control Pathogens and Spoilage
aspects). For irradiation of food, see ISO 14470. In those areas
Microorganisms
covered by these standards, they take precedence. Information
F1885Guide for Irradiation of Dried Spices, Herbs, and
about effective or regulatory dose limits for food products is
Vegetable Seasonings to Control Pathogens and Other
notwithinthescopeofthispractice(seeASTMGuidesF1355,
Microorganisms
F1356, F1736, and F1885).
2
2.2 ISO/ASTM Standards:
1.5 This document is one of a set of standards that provides
51261Practice for Calibration of Routine Dosimetry Sys-
recommendations for properly implementing and utilizing
tems for Radiation Processing
dosimetry in radiation processing. It is intended to be read in
51275Practice for Use of a Radiochromic Film Dosimetry
conjunction with ISO/ASTM 52628, “Practice for Dosimetry
System
in Radiation Processing”.
51539Guide for the Use of Radiation-Sensitive Indicators
NOTE 1—For guidance in the calibration of routine dosimetry systems,
51608PracticeforDosimetryinanX-Ray(Bremsstrahlung)
seeISO/ASTMPractice51261.Forfurtherguidanceintheuseofspecific
Facility for Radiation Processing
dosimetry systems, see relevant ISO/ASTM Practices. For discussion of
radiation dosimetry for pulsed radiation, see ICRU Report 34. 51702Practice for Dosimetry in a Gamma Facility for
Radiation Processing
1.6 This standard does not purport to address all of the
51707Guide for Estimating Uncertainties in Dosimetry for
safety concerns, if any, associated with its use. It is the
Radiation Processing
responsibility of the user of this standard to establish appro-
51818Practice for Dosimetry in an Electron Beam Facility
for Radiation Processing at Energies Between 80 and 300
1
This practice is under the jurisdiction of ASTM Committee E61 on Radiation
keV
Processing and is the direct responsibility of Subcommittee E61.03 on Dosimetry
52628Practice for Dosimetry in Radiation Processing
Application, and is also under the jurisdiction of ISO/TC 85/WG 3.
Current edition approved Sept. 8, 2014. Published February 2015. Originally
published as E 1649–94. Last previous ASTM edition E 1649–00. ASTM
ε1 2
E1649–94 was adopted by ISO in 1998 with the intermediate designation ISO For referenced ASTM and ISO/ASTM standards, visit the ASTM website,
15569:1998(E). The present International Standard ISO/ASTM 51649:2015(E) is a www.astm.org, or contact ASTM Customer Service at [e-mail]. For
major revision of the last previous edition ISO/ASTM 51649:2005(E), which Annual Book of ASTM Standards volume information, refer to the standard’s
replaced ISO/ASTM 51649:2002(E). Document Summary page on the ASTM website.
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ISO/ASTM 51649:2015(E)
52701Guide for Performance Characterization of Dosim- ISO/IEC 17025, or has a quality system consistent with the
eters and Dosimetry Systems for Use in Radiation Pro- requirements of ISO/IEC 17025.
cessing
3.1.2.1 Discussion—A recognized national metrology insti-
3
2.3 ISO Standards:
tute or other calibration laboratory accredited to ISO/IEC
ISO 11137-1Sterilization of Health Care Products–Radia-
17025 or its equivalent should be used for issue of reference
tion – Part 1: Requirements for development, validation,
standard dosimeters or irradiation of dosimeters in order to
and routine control of a sterilization process for medical
ensure traceability to a national or international standard. A
devices
calibration certificate provided by a laboratory not having
ISO 11137-3Sterilization of Health Care Products–Radia-
formal recognition or accreditation will not necessarily be
tion – Part 3: Guidance on dosimetric aspects
proof of traceability to a national or international standard.
ISO 14470 Food Irradiation – Requirements for the
3.1.3 average beam current—time-averaged electron beam
development,validationandroutinecontroloftheprocess
current; for a pulsed accelerator, the averaging shall be done
of irradiation using ionizing radiation for the treatment of
over a large number of pulses (see Fig. 1).
food
3.1.4 beam length—dimension of the irradiation zone along
ISO 10012Measurement Management Systems – Require-
the direction of product movement at a specified distance from
ments for Measurement Processes and Measuring Equip-
the accelerator window (see Fig. 2).
ment
ISO/IEC 17025General Requirements for the Competence 3.1.4.1 Discussion—Beam length is therefore perpendicular
of Calibration and Testing Laboratories tobeamwidthandtotheelectronbeamaxis.Incaseofproduct
that is stationary during irradiation, ‘beam length’ and ‘beam
2.4 International Commission on Radiation Units and Mea-
4
surements (ICRU) Reports: width’ may be interchangeable.
ICRU Report 34The Dosimetry of Pulsed Radiation
3.1.5 beam width (W )—dimension of the irradiation zone
b
ICRU Report 35Radiation Dosimetry: Electron Beams with
perpendicular to the direction of product movement at a
Energies Between 1 and 50 MeV
specified distance from the accelerator window (see Fig. 2).
ICRU Report 37Stopping Powers for Electrons and Posi-
3.1.5.1 Discussion—For a radiation processing facility with
trons
a conveyor system, the beam width is usually perpendicular to
ICRU Report 80Dosimetry for Use in Radiation Processing
the direction of motion of the conveyor (see Fig. 2). Beam
ICRU Report 85aFundamental Quantities and Units for
widthisthedistancebetweentwopointsalongthedoseprofile,
Ionizing Radiation
which are at a defined level from the maximum dose region in
2.5 Joint Committee for Guides in Metrology (JCGM)
theprofile(seeFig.3).Varioustechniquesmaybeemployedto
5
Reports:
produceanelectronbeamwidthadequatetocovertheprocess-
JCGM 100:2008, GUM 1995, with minor corrections,
ing zone, for example, use of electromagnetic scanning of a
Evaluationofmeasurementdata–Guidetotheexpression
pencil beam (in which case beam width is also referred to as
of uncertainty in measurement
scan width), defocussing elements, and scattering foils.
3. Terminology
3.1.6 compensating dummy—see simulated product.
3.1 Definitions:
3.1.7 depth-dose distribution—variation of absorbed dose
3.1.1 absorbed dose (D)—quantity of ionizing radiation
with depth from the incident surface of a material exposed to
energy imparted per unit mass of a specified material.
a given radiation.
3.1.1.1 Discussion—(1) The SI unit of absorbed dose is the
3.1.7.1 Discussion—Typical distributions along the beam
gray (Gy), where 1 gray is equivalent to the absorption of 1
axis in homogeneous materials produced by a normally inci-
joule per kilogram in the specified material (1 Gy = 1 J/kg).
dent monoenergetic electron beam are shown in Annex A2.
The mathematical relationship is the quotient of dε¯ by dm,
3.1.8 dose uniformity ratio (DUR)—ratio of the maximum
where dε¯ is the mean incremental energy imparted by ionizing
to the minimum absorbed dose within the irradiated product.
radiation to matter of incremental mass dm. (See ICRU Report
3.1.8.1 Discussion—The concept is also referred to as the
85a.)
max/min dose ratio.
D 5 dHε/dm
3.1.9 dosimetry system—system used for measuring ab-
3.1.1.2 Discussion—(2) Absorbed dose is sometimes re-
sorbed dose, consisting of dosimeters, measurement instru-
ferred to simply as dose.
ments and their associated reference standards, and procedures
3.1.2 approved laboratory—laboratory that is a recognized
for the system’s use.
nationalmetrologyinstitute;orhasbeenformallyaccreditedto
3.1.10 electron beam energy—kinetic energy of the acceler-
ated electrons in the beam. Unit: J
3
Available from International Organization for Standardization, 1 Rue de
3.1.10.1 Discussion—Electron volt (eV) is often used as the
Varembé, Case Postale 56, CH-1211 Geneva 20, Switzerland.
4 -19
Available from the International Commission on Radiation Units and
unit for electron beam energy where 1 eV = 1.602·10 J. In
Measurements, 7910 Woodmont Ave., Suite 800, Bethesda MD 20814, U.S.A.
radiation processing, where beams with a broad electron
5
Document produced byWorking Group 1 of the Joint Committee for Guides in
energy spectrum are frequently used, the terms most probable
Metrology (JCGM/WG 1). Available free of charge at the BIPM website (http://
www.bipm.org). energy (E ) and average energy (E ) are common. They are
p a
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ISO/ASTM 51649:2015(E)
FIG. 1 Example showing pulse beam current (I ), average beam current (I ), (pulse width (W) and repetition rate (f) for a pulsed
pulse avg
accelerator
3.1.13 installation qualification (IQ)—process of obtaining
and documenting evidence that equipment has been provided
and installed in accordance with its specification.
3.1.14 operationalqualification(OQ)—processofobtaining
and documenting evidence that installed equipment operates
within predetermined limits when used in accordance with its
operational procedures.
3.1.15 performance qualification (PQ)—process of obtain-
ing and documenting evidence that the equipment, as installed
and operated in accordance with operational procedures, con-
sistently performs in accordance with predetermined criteria
and thereby yields product meeting its specification.
3.1.16 process load—volume of material with a specified
product loading configuration irradiated as a single entity.
3.1.17 production run—seriesofprocessloadsconsistingof
FIG. 2 Diagram showing beam length and beam width for a materials or products having similar radiation-absorption
scanned beam using a conveyor system
characteristics, that are irradiated sequentially to a specified
range of absorbed dose.
3.1.18 referencematerial—homogeneousmaterialofknown
linked to the practical electron range R and half-value
p
depth R by empirical equations (see Fig. 4 and Annex A4). radiation absorption and scattering properties used to establish
50
characteristics of the irradiation process, such as scan
3.1.11 electron beam facility—establishment that uses ener-
uniformity,depth-dosedistribution,andreproducibilityofdose
getic electrons produced by particle accelerators to irradiate
delivery.
product.
3.1.12 electron energy spectrum—particle fluence distribu- 3.1.19 reference plane—selected plane in the radiation zone
tion of electrons as a function of energy. that is perpendicular to the electron beam axis.
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ISO/ASTM 51649:2015(E)
FIG. 3 Example of electron-beam dose distribution along the scan direction, where the beam width is specified at a defined fractional
level f of the average maximum dose D
max
where the relationship of the dose at this position with the
minimum and maximum dose has been established.
3.1.21 simulated product—material with radiation absorp-
tion and scattering properties similar to those of the product,
material or substance to be irradiated.
3.1.21.1 Discussion—Simulated product is used during irra-
diator characterization as a substitute for the actual product,
material or substance to be irradiated. When used in routine
production runs in order to compensate for the absence of
product, simulated product is sometimes referred to as com-
pensating dummy. When used for absorbed-dose mapping,
simulated product is sometimes referred to as phantom mate-
rial.
3.1.22 standardized depth (z)—thickness of the absorbing
material expressed as the mass per unit area, which is equal to
the product of depth in the material t and density ρ.
D : Dose at entrance surface
e
3.1.22.1 Discussion—If m is the mass of the material
R : Depth at which dose at descending part of curve equals D
opt e
R : Depth at which dose has decreased to 50 % of its maximum
beneath area A of the material through which the beam passes,
50
value
then:
R : Depth at which dose has decreased to 50 % of D
50e e
R : Depth where extrapolated straight line of descending curve
p z 5 m/A 5 tρ
2
meets depth axis
The SI unit of z is in kg/m , however, it is common practice
3
to express t in centimetres and ρ in grams per cm , then z is
FIG. 4 A typical depth-dose distribution for an electron beam in
in grams per square centimetre. Standardized depth may also
a homogeneous material
be referred to as surface density, area density, mass-depth or
mass-thickness.
3.2 Definitions of Terms Specific to This Standard:
3.1.20 routine monitoring position—position where ab-
3.2.1 beam power—product of the average electron beam
sorbed dose is monitored during routine processing to ensure
energy and the average beam current.
thattheproductisreceivingtheabsorbeddosespecifiedforthe
3.2.2 beam spot—shape of the unscanned electron beam
process.
incident on the reference plane.
3.1.20.1 Discussion—This position may be a location of
minimumormaximumdoseintheprocessloadoritmaybean 3.2.3 continuous-slowing-down-approximation (CSDA)
alternate convenient location in, on or near the process load range (r )—average pathlength traveled by a charged particle
0
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ISO/ASTM 51649:2015(E)
as it slows down to rest, calculated in the continuous-slowing- 3.2.9 optimum thickness (R )—depth in homogeneous ma-
opt
down-approximation method. terial at which the absorbed dose equals its value at the
3.2.3.1 Discussion—In this approximation, the rate of en- entrance surface of the material (see Fig. 4).
ergy loss at every point along the track is assumed to be equal
3.2.10 practical electron range (R )—depth in homoge-
p
to the total stopping power. Energy-loss fluctuations are
neous material to the point where the tangent at the steepest
neglected. The CSDA range is obtained by integrating the
point (the inflection point) on the almost straight descending
reciprocal of the total stopping power with respect to energy.
portion of the depth-dose distribution curve meets the extrapo-
Valuesof r forawiderangeofelectronenergiesandformany
0 lated X-ray background (see Fig. 4 and Fig. A2.6 in Annex
materials can be obtained from ICRU Report 37.
A2).
3.2.4 duty cycle (for a pulsed accelerator)—fraction of time 3.2.10.1 Discussion—Penetration can be measured from
the beam is effectively on. experimental depth-dose distributions in a given material.
Other forms of electron range are found in the dosimetry
3.2.4.1 Discussion—Duty cycle is the product of the pulse
literature, for example, extrapo
...