ISO/ASTM 51649:2005
(Main)Practice for dosimetry in an electron beam facility for radiation processing at energies between 300 keV and 25 MeV
Practice for dosimetry in an electron beam facility for radiation processing at energies between 300 keV and 25 MeV
ISO/ASTM 51649:2005 covers dosimetric procedures to be followed in Installation Qualification, Operational Qualification and Performance Qualifications (IQ, OQ, PQ), and routine processing at electron beam facilities to ensure that the product has been treated with an acceptable range of absorbed doses. Other procedures related to IQ, OQ, PQ, and routine product processing that may influence absorbed dose in the product are also discussed.
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
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Standards Content (Sample)
INTERNATIONAL ISO/ASTM
STANDARD 51649
Second edition
2005-05-15
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 51649:2005(E)
© ISO/ASTM International 2005
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ISO/ASTM 51649:2005(E)
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ISO/ASTM FDIS 51649:2005(E)
Contents Page
1 Scope . 1
2 Referenced documents . 1
3 Terminology . 2
4 Significance and use . 5
5 Radiation source characteristics . 6
6 Types of irradiation facilities . 6
7 Dosimetry systems . 6
8 Process parameters . 7
9 Installation qualification . 7
10 Operational qualification . 8
11 Performance qualification . 9
12 Routine product processing . 11
13 Measurement uncertainty . 12
14 Certification . 12
15 Keywords . 12
Annexes . 12
Bibliography . 29
Figure 1 Example pulse current (I ), average beam current (I ), pulse width (W) and
pulse avg
repetition rate (f) for a pulsed accelerator . 2
Figure 2 Diagram showing beam length and width for a scanned beam using a conveyor
system . 3
Figure 3 Example of electron-beam dose distribution along the beam width with the width noted
at some defined fractional level f of the average maximum dose D . 3
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 A1.1 Calculated depth-dose distribution curves in various homogeneous polymers for
normally incident monoenergetic electrons at 5.0 MeV using the Program ITS3 . 13
Figure A1.2 Calculated depth-dose distribution curves in various homogeneous metals for
normally incident monoenergetic electrons at 5.0 MeV using the Program ITS3 . 14
Figure A1.3 Calculated depth-dose distribution curves in polystyrene for normally incident
electrons at monoenergetic energies from 300 to 1000 keV using the Program ITS3 . 15
Figure A1.4 Calculated depth-dose distribution curves in polystyrene for normally incident, plane
parallel incident electrons at monoenergetic energies from 1.0 to 5.0 MeV using the program ITS3
.................................................................................................................................................. 16
Figure A1.5 Calculated depth-dose distribution curves in polystyrene for normally incident, plane
parallel incident electrons at monoenergetic energies from 5.0 to 12.0 MeV using the program
ITS3 . 17
Figure A1.6 Calculated depth-dose distribution curves in Al and Ta for normally incident, plane
parallel incident electrons at a monoenergetic energy of 25 MeV using the program ITS3 . 18
Figure A1.7 Electron energy deposition D (0) at the entrance surface of a polystyrene absorber
e
as a function of incident electron energy from 0.3 MeV to 12 MeV corresponding to the Monte
Carlo calculated data shown in Figs. A1.3-A1.5 . 18
Figure A1.8 Electron energy deposition D (0) at the entrance surface of a polystyrene absorber
e
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. A1.3 and Fig. A1.4 . 19
Figure A1.9 Superposition of theoretically calculated depth-dose distribution curves for aluminum
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ISO/ASTM FDIS 51649:2005(E)
irradiated with 5 MeV monoenergetic electrons from both sides with different thicknesses (T) and
from one side using experimental data presented in Refs (12 and 25) . 19
Figure A1.10 Calculated correlations between optimum electron range R , half-value depth R ,
opt 50
half-entrance depth R , and practical range R , and incident electron energy for polystyrene
50e p
using Fig. A1.3 and Fig. A1.4 . 20
Figure A1.11 Calculated correlations between optimum electron range R , half-value depth R ,
opt 50
half-entrance depth R , and practical range R , and incident electron energy for polystyrene
50e p
using Figs. A1.4 and A1.5 . 20
Figure A1.12 Measured depth-dose distribution curves for nominal 10 MeV electron beams
,
incident on polystyrene for two electron beam facilities . 21
Figure A1.13 Depth-dose distribution curves in stacks of cellulose acetate films backed with
wood, aluminum, and iron for incident electrons with 400 keV energy . 22
Figure A1.14 Depth-dose distributions with 2 MeV electrons incident on polystyrene absorbers at
various angles from the normal direction . 22
Figure A3.1 Measured depth-dose distribution curve in aluminum for a 10 MeV electron beam in
comparison with the calculated relative depth-dose distribition using ITS3 . 25
Figure A3.2 Stack energy measurement device . 26
Figure A3.3 Wedge energy measurement device . 27
Table A1.1 Key parameters for measured depth-dose distribution curves presented in Fig. A1.12 . 21
Table A1.2 Electron energy deposition D (0) at the entrance surface of a polystyrene absorber as
e
a function of incident electron energy from 0.3 MeV to 12 MeV corresponding to the calculated
curves shown in Figs. A1.3-A1.5 . 21
Table A1.3 Compatible units for the quantities used in Eq A1.1 . 22
Table A3.1 Some relevant properties of common reference materials . 24
Table A3.2 Half-value depth R , half-entrance depth R , optimum thickness R and practical
50 50e opt
range R in polystyrene for monoenergetic electron energies E from 0.3 to 12 MeV derived from
p
Monte Carlo calculations . 24
Table A3.3 Half-value depth R , practical range R and extrapolated range R in aluminum for
50 p ex
monoenergetic electron energies E from 2.5 to 25 MeV derived from Monte Carlo calculations . 25
iv © ISO/ASTM International 2005 – All rights reserved
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ISO/ASTM 51649:2005(E)
Foreword
ISO(theInternationalOrganizationforStandardization)isaworldwidefederationofnationalstandardsbodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are circulated to the member bodies for
voting. Publication as an International Standard requires approval by at least 75% of the member bodies
casting a vote.
ASTM International is one of the world’s largest voluntary standards development organizations with global
participation from affected stakeholders. ASTM technical committees follow rigorous due process balloting
procedures.
A project between ISO and ASTM International has been formed to develop and maintain a group of
ISO/ASTM radiation processing dosimetry standards. Under this project, ASTM Subcommittee E10.01,
Dosimetry for Radiation Processing, is responsible for the development and maintenance of these dosimetry
standards with unrestricted participation and input from appropriate ISO member bodies.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. Neither ISO nor ASTM International shall be held responsible for identifying any or all such patent
rights.
International Standard ISO/ASTM 51649 was developed byASTM Committee E10, Nuclear Technology and
Applications, through Subcommittee E10.01, and by Technical Committee ISO/TC 85, Nuclear energy.
This second edition cancels and replaces the first edition (ISO/ASTM 51649:2002), which has been
technically revised.
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ISO/ASTM 51649:2005(E)
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 2. Referenced documents
2
1.1 This practice covers dosimetric procedures to be fol- 2.1 ASTM Standards:
lowed in Installation Qualification, Operational Qualification E 170 Terminology Relating to Radiation Measurements
and Performance Qualifications (IQ, OQ, PQ), and routine and Dosimetry
processing at electron beam facilities to ensure that the product E 1026 Practice for Using the Fricke Reference Standard
has been treated with an acceptable range of absorbed doses. Dosimetry System
Other procedures related to IQ, OQ, PQ, and routine product E 2232 Guide for Selection and Use of Mathematical Meth-
processing that may influence absorbed dose in the product are odsforCalculatingAbsorbedDoseinRadiationProcessing
also discussed. Applications
E 2303 Guide to Dose Mapping in Radiation Processing
NOTE 1—For guidance in the selection and calibration of dosimeters,
Facilities
see ISO/ASTM Guide 51261. For further guidance in the use of specific
2
2.2 ISO/ASTM Standards:
dosimetry systems, and interpretation of the measured absorbed dose in
51205 PracticeforUseofaCeric-CerousSulfateDosimetry
the product, also see ISO/ASTM Practices 51275, 51276, 51431, 51607,
51631, 51650, and 51956. For use with electron energies above 5 MeV,
System
see Practice E 1026, and ISO/ASTM Practices 51205, 51401, 51538, and
51261 Guide for Selection and Calibration of Dosimetry
51540 for discussions of specific large volume dosimeters. For discussion
Systems for Radiation Processing
of radiation dosimetry for pulsed radiation, see ICRU Report 34.
51275 Practice for Use of a Radiochromic Film Dosimetry
1.2 The electron beam energy range covered in this practice
System
is between 300 keV and 25 MeV, although there are some
51276 Practice for Use of a Polymethylmethacrylate Do-
discussions for other energies.
simetry System
1.3 Dosimetry is only one component of a total quality
51400 Practice for Characterization and Performance of a
assurance program for an irradiation facility. Other measures
High-Dose Radiation Dosimetry Calibration Laboratory
besides dosimetry may be required for specific applications
51401 Practice for Use of a Dichromate Dosimetry System
such as medical device sterilization and food preservation.
51431 Practice for Dosimetry in Electron and X-ray
1.4 Other specific ISO and ASTM standards exist for the
(Bremsstrahlung) Irradiation Facilities for Food Process-
irradiation of food and the radiation sterilization of health care
ing
products. For food irradiation, see ISO/ASTM Practice 51431.
51538 Practice for Use of an Ethanol-Chlorobenzene Do-
For the radiation sterilization of health care products, see ISO
simetry System
11137. In those areas covered by ISO 11137, that standard
51539 Guide for the Use of Radiation-Sensitive Indicators
takes precedence.
51540 Practice for Use of a Radiochromic Liquid Solution
1.5 This standard does not purport to address all of the
Dosimetry System
safety concerns, if any, associated with its use. It is the
51607 Practice for Use of the Alanine–EPR Dosimetry
responsibility of the user of this standard to establish appro-
System
priate safety and health practices and determine the applica-
51631 Practice for Use of Calorimetric Dosimetry Systems
bility of regulatory requirements prior to use.
for Electron Beam Measurements and Dosimeter Calibra-
tions
51650 Practice for Use of a Cellulose Triacetate Dosimetry
1
This practice is under the jurisdiction of ASTM Committee E10 on Nuclear System
Technology and Applications and is the direct responsibility of Subcommittee
51707 Guide for Estimating Uncertainties in Dosimetry for
E10.01 on Dosimetry for Radiation Processing, and is also under the jurisdiction of
Radiation Processing
ISO/TC 85/WG 3.
Current edition approved by ASTM June 1, 2004. Published May 15, 2005.
OriginallypublishedasE 1649–94.LastpreviousASTMeditionE 1649–00.ASTM
e1 2
E 1649–94 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 51649:2005(E) is a www.astm.org, or contact ASTM Customer Service at service@astm.org. For
major revision of the last previous edition ISO/ASTM 51649:2002(E), which Annual Book of ASTM Standards volume information, refer to the standard’s
replaced ISO 15569. Document Summary page on the ASTM website.
© ISO/ASTM International 2005 – All rights reserved
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ISO/ASTM 51649:2005(E)
– –
51956 Practice for Thermoluminescence Dosimetry (TLD)
ship is the quotient of de by dm, where de is the mean
Systems for Radiation Processing
incremental energy imparted by ionizing radiation to matter of
3
2.3 ISO Standard:
incremental mass dm.
ISO 11137 Sterilization of Health Care Products–Require-
–
D 5 de/dm
ments for Validation and Routine Control–Radiation Ster-
ilization
3.1.1.1 Discussion—The discontinued unit for absorbed
2.4 International Commission on Radiation Units and
dose is the rad (1 rad = 100 erg/g = 0.01 Gy). Absorbed dose
4
Measurements (ICRU) Reports:
is sometimes referred to simply as dose.
ICRU Report 34 The Dosimetry of Pulsed Radiation
3.1.2 average beam current—time-averaged electron beam
ICRUReport35 RadiationDosimetry:ElectronBeamswith
current; for a pulsed machine, the averaging shall be done over
Energies Between 1 and 50 MeV
a large number of pulses (see Fig. 1).
ICRU Report 37 Stopping Powers for Electrons and
3.1.3 beam length—dimension of the irradiation zone, per-
Positrons
pendicular to the beam width and direction of the electron
ICRU Report 60 Fundamental Quantities and Units for
beam at a specified distance from the accelerator window (see
Ionizing Radiation
Fig. 2).
3. Terminology 3.1.4 beam power—product of the average electron beam
energy and the average beam current.
3.1 Definitions:
3.1.5 beam spot—shape of the unscanned electron beam
3.1.1 absorbed dose (D)—quantity of ionizing radiation
incident on the reference plane.
energy imparted per unit mass of a specified material. The SI
unit of absorbed dose is the gray (Gy), where 1 gray is 3.1.6 beam width—dimension of the irradiation zone in the
equivalent to the absorption of 1 joule per kilogram in the direction that the beam is scanned, perpendicular to the beam
specified material (1 Gy = 1 J/kg). The mathematical relation- lengthanddirectionoftheelectronbeamataspecifieddistance
from the accelerator window (see Fig. 2).
3.1.6.1 Discussion—For a radiation processing facility with
3
Available from International Organization for Standardization, 1 Rue de
a conveyor system, the beam width is usually perpendicular to
Varembé, Case Postale 56, CH-1211 Geneva 20, Switzerland.
4 the flow of motion of the conveyor (see Fig. 2). Beam width is
Available from the International Commission on Radiation Units and Measure-
ments, 7910 Woodmont Ave., Suite 800, Bethesda MD 20814, U.S.A. the distance between two points along the dose profile, which
FIG. 1 Example pulse current (I ), average beam current (I ), pulse width (W) and repetition rate (f) for a pulsed accelerator
pulse avg
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ISO/ASTM 51649:2005(E)
configuration, or simulated product used at the beginning or
end of a production run, to compensate for the absence of
product.
3.1.7.1 Discussion—Simulatedproductorphantommaterial
may be used during irradiator characterization as a substitute
for the actual product, material or substance to be irradiated.
3.1.8 continuous-slowing-down-approximation (CSDA)
range (r )—average pathlength traveled by a charged particle
0
as it slows down to rest, calculated in the continuous-slowing-
down-aproximation method.
3.1.8.1 Discussion—In this approximation, the rate of en-
ergy loss at every point along the track is assumed to be equal
to the total stopping power. Energy-loss fluctuations are
neglected. The CSDA range is obtained by integrating the
reciprocal of the total stopping power with respect to energy.
Values of r for a wide range of electron energies and for many
0
materials can be obtained from ICRU Report 37.
3.1.9 depth-dose distribution—variation of absorbed dose
FIG. 2 Diagram showing beam length and width for a scanned
beam using a conveyor system
with depth from the incident surface of a material exposed to
a given radiation.
3.1.9.1 Discussion—Typical distributions in homogeneous
are at a defined level from the maximum dose region in the materials produced by an electron beam along the beam axis
are shown in Figs. A1.1 and A1.2. See Annex A1.
profile (see Fig. 3). Various techniques may be employed to
produce an electron beam width adequate to cover the process-
3.1.10 dose uniformity ratio—ratio of the maximum to the
ing zone, for example, use of electromagnetic scanning of a minimum absorbed dose within the process load. The concept
pencil beam (in which case beam width is also referred to as
is also referred to as the max/min dose ratio.
scan width), defocussing elements, and scattering foils.
3.1.11 dosimetry system—system used for determining ab-
3.1.7 compensating dummy—simulatedproductusedduring sorbed dose, consisting of dosimeters, measurement instru-
routine production runs in process loads that contain less ments and their associated reference standards, and procedures
product than specified in the documented product-loading for the system’s use.
NOTE—McKeown, J., AECL Accelerators, private communication, 1993. Example of a beam width profile of an AECL Impela accelerator.
FIG. 3 Example of electron-beam dose distribution along the beam width with the width noted at some defined fractional level f of the
average maximum dose D
max
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ISO/ASTM 51649:2005(E)
3.1.12 duty cycle—for a pulsed accelerator, the fraction of 3.1.19 optimum thickness (R )—depth in homogeneous
opt
time the beam is effectively on; it is the product of the pulse material at which the absorbed dose equals the absorbed dose
width in seconds and the pulse rate in pulses per second. at the surface where the electron beam enters (see Fig. 4).
3.1.13 electron beam energy—average kinetic energy of the 3.1.20 practical electron range (R )—depth in homoge-
p
accelerated electrons in the beam. Unit: J neous material to the point where the tangent at the steepest
3.1.13.1 Discussion—Electron volt (eV) is often used as the point (the inflection point) on the almost straight descending
-19
portion of the depth-dose distribution curve meets the extrapo-
unit for electron beam energy where 1 eV = 1.602·10 J
(approximately). In radiation processing, where beams with a latedX-raybackground(seeFig.4andFig.A1.6inAnnexA1).
broad electron energy spectrum are frequently used, the terms 3.1.21 extrapolated electron range (R )—depth in homo-
ex
most probable energy (E ) and average energy (E ) are geneous material to the point where the tangent at the steepest
p a
common. They are linked to the practical electron range R point (the inflection point) on the almost straight descending
p
and half-value depth R by empirical equations. portion of the depth-dose distribution curve meets the depth
50
3.1.14 electron beam facility—establishment that uses ener- axis (see Fig. A1.6 in Annex A1).
getic electrons produced by particle accelerators to irradiate 3.1.22 process load—volume of product with a specified
product. loading configuration processed as a single entity; this term is
not relevant to bulk-flow processing.
3.1.15 electron energy spectrum—particle fluence distribu-
tion of electrons as a function of energy. 3.1.23 production run—seriesofprocessloadsconsistingof
materials,orproductshavingsimilarradiation-absorptionchar-
3.1.16 electron range—penetration distance in a specific,
acteristics, that are irradiated sequentially to a specified range
totally absorbing material along the beam axis of the electrons
of absorbed dose.
incident on the material (equivalent to practical electron range,
3.1.24 pulse beam current, for a pulsed accelerator—beam
R ).
P
current averaged over the top ripples (aberrations) of the pulse
3.1.16.1 Discussion—R can be measured from experimen-
P
current waveform; this is equal to I /wf, where I is the
tal depth-dose distributions in a given material. Other forms of
avg avg
average beam current, w is the pulse width, and f is the pulse
electron range are found in the dosimetry literature, for
rate (see Fig. 5).
example, extrapolated range derived from depth-dose data and
3.1.25 pulse rate, for a pulsed accelerator—pulse repetition
the continuous-slowing-down-approximation range (the calcu-
lated pathlength traversed by an electron in a material in the frequency in hertz, or pulses per second; this is also referred to
as the repetition (rep) rate.
course of completely slowing down). Electron range is usually
-2
expressed in terms of mass per unit area (kg·m ), but some- 3.1.26 pulse width, for a pulsed accelerator—time interval
times in terms of thickness (m) for a specified material. between two points on the leading and trailing edges of the
pulse current waveform where the current is 50 % of its peak
3.1.17 half-entrance depth (R )—depth in homogeneous
50e
material at which the absorbed dose has decreased down to value (see Fig. 5).
50 % of the absorbed dose at the surface of the material (see 3.1.27 reference material—homogeneous material of
Fig. 4). known radiation absorption and scattering properties used to
establish characteristics of the irradiation process, such as scan
3.1.18 half-value depth (R )—depth in homogeneous ma-
50
uniformity, depth-dose distribution, throughput rate, and repro-
terial at which the absorbed dose has decreased down to 50 %
ducibility of dose delivery.
of its maximum value (see Fig. 4).
3.1.28 reference plane—selected plane in the radiation zone
that is perpendicular to the electron beam axis.
3.1.29 scannedbeam—electronbeamthatissweptbackand
forth with a varying magnetic field.
3.1.29.1 Discussion—This is most commonly done along
one dimension (beam width), although two-dimensional scan-
ning (beam width and length) may be used with high-current
electron beams to avoid overheating the beam exit window of
the accelerator or product under the scan horn.
3.1.30 scan frequency—number of complete scanning
cycles per second expressed in Hz.
3.1.31 scan uniformity—degree of uniformity of the dose
measured along the scan direction.
3.1.32 simulated product—mass of material with attenua-
tion and scattering properties similar to those of the product,
material or substance to be irradiated.
3.1.32.1 Discussion—Simulated product is used during ir-
radiator characterization as a substitute for the actual product,
material or substance to be irradiated. When used in routine
FIG. 4 A typical depth-dose distribution for an electron beam in a
homogeneous material production runs, it is sometimes referred to as compensating
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ISO/ASTM 51649:2005(E)
FIG. 5 Typical pulse current waveform from an S-Band linear accelerator
dummy. When used for absorbed-dose mapping, simulated 4.1.3 Curing of composite materials,
product is sometimes referred to as phantom material. 4.1.4 Sterilization of medical devices,
3.1.33 standardized depth (z)—thickness of the absorbing 4.1.5 Disinfection of consumer products,
material expressed as the mass per unit area, which is equal to 4.1.6 Food irradiation (parasite and pathogen control, insect
the depth in the material t times the density r.If m is the mass disinfestation, and shelf-life extension),
of the material beneath that area and A is the area of the 4.1.7 Control of pathogens and toxins in drinking water,
material through which the beam passes, then: 4.1.8 Control of pathogens and toxins in liquid or solid
waste,
z 5 m/A 5 tr
4.1.9 Modification of characteristics of semiconductor de-
If t is in meters and r in kilograms per cubic meter, then z is
vices,
in kilograms per square meter.
4.1.10 Color enhancement of gemstones and other materi-
3.1.33.1 Discussion—It is common practice to express t in
als, and
3
centimeters and r in grams per cm , then z is in grams per
4.1.11 Rese
...
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