ISO/ASTM 51204:2002

Practice for dosimetry in gamma irradiation facilities for food processing

This practice outlines dosimetric procedures to be followed in irradiator characterization, process qualification, and routine processing of food with ionizing radiation from isotopic gamma sources to ensure that all the product has been treated within a predetermined range of absorbed dose. Other procedures related to irradiator characterization, process qualification, and routine processing that may influence absorbed dose in the product are also discussed. Information about effective or regulatory dose limits for food products is not within the scope of this practice (see ASTM Guides F 1355 and F 1356). NOTE 1 Dosimetry is only one component of a total quality assurance program for adherence to good manufacturing practices used in the production of safe and wholesome food. NOTE 2 ISO/ASTM Practice 51431 describes dosimetric procedures for electron beam and bremsstrahlung (X-ray) irradiation facilities for food processing. For guidance in the selection and calibration of dosimeters, and interpretation of measured absorbed dose in the product, see ISO/ASTM Guide 51261 and ASTM Practice E 666. For the use of specific dosimetry systems, see ASTM Practices E 668, E 1026 and ISO/ASTM Practices 51205, 51275, 51276, 51310, 51401, 51538, 51540, 51607 and 51650. For discussion of radiation dosimetry for gamma rays and X-rays also see ICRU Report 14. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

Pratique de la dosimétrie dans les installations de traitement des produits alimentaires par irradiation gamma

General Information

• Status: Withdrawn
• Publication Date: 17-Apr-2002
• Withdrawal Date: 17-Apr-2002
• ICS: 17.240 - Radiation measurements
• ICS: 67.020 - Processes in the food industry
• 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: 9599 - Withdrawal of International Standard
• Completion Date: 25-Oct-2004

Relations

• Revised: ISO/ASTM 51204:2004 - Practice for dosimetry in gamma irradiation facilities for food processing
• Effective Date: 15-Apr-2008
• Revises: ISO 15554:1998 - Practice for dosimetry in gamma irradiation facilities for food processing
• Effective Date: 15-Apr-2008

Standards Content (Sample)

INTERNATIONAL ISO/ASTM
STANDARD 51204
First edition
2002-03-15
Practice for dosimetry in gamma
irradiation facilities for food processing
Pratique de la dosimétrie dans les installations de traitement des
produits alimentaires par irradiation gamma
Reference number
ISO/ASTM 51204:2002(E)
© ISO/ASTM International 2002

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ISO/ASTM 51204:2002(E)
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ii © ISO/ASTM International 2002 – All rights reserved

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ISO/ASTM 51204:2002(E)
Contents Page
1 Scope . 1
2 Referenced documents . 1
3 Terminology . 2
4 Significance and use . 2
5 Radiation source characteristics . 3
6 Types of facilities . 3
7 Dosimetry systems . 3
8 Installation qualification . 4
9 Process qualification . 5
10 Routine product processing . 6
11 Certification . 7
12 Measurement uncertainty . 8
13 Keywords . 8
Bibliography . 8
Figure 1 An example of the maximum and minimum absorbed dose locations in a typical product
.................................................................................................................................................. 5
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ISO/ASTM 51204:2002(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(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 pilot project between ISO and ASTM International has been formed to develop and maintain a group of
ISO/ASTM radiation processing dosimetry standards. Under this pilot 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 International Standard 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 51204 was developed by ASTM Committee E10, Nuclear Technology and
Applications, through Subcommittee E10.01, and by Technical Committee ISO/TC 85, Nuclear Energy.
iv © ISO/ASTM International 2002 – All rights reserved

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ISO/ASTM 51204:2002(E)
Standard Practice for
Dosimetry in Gamma Irradiation Facilities for Food
1
Processing
This standard is issued under the fixed designation ISO/ASTM 51204; 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 E 275 Practice for Describing and Measuring Performance
of Ultraviolet, Visible, and Near Infrared Spectrophotom-
1.1 This practice outlines dosimetric procedures to be fol-
4
eters
lowed in irradiator characterization, process qualification, and
3
E 456 Terminology Relating to Quality and Statistics
routine processing of food with ionizing radiation from isoto-
E 666 Practice for Calculating Absorbed Dose from Gamma
pic gamma sources to ensure that all product has been treated
2
or X Radiation
within a predetermined range of absorbed dose. Other proce-
E 668 Practice for Application of Thermoluminescence-
dures related to irradiator characterization, process qualifica-
Dosimetry (TLD) Systems for Determining Absorbed Dose
tion, and routine processing that may influence absorbed dose
2
in Radiation-Hardness Testing of Electronic Devices
in the product are also discussed. Information about effective
E 925 Practice for the Periodic Calibration of Narrow Band-
or regulatory dose limits for food products is not within the
4
Pass Spectrophotometers
scope of this practice (see ASTM Guides F 1355 and F 1356).
E 958 Practice for Measuring Practical Spectral Bandwidth
NOTE 1—Dosimetry is only one component of a total quality assurance 4
of Ultraviolet-Visible Spectrophotometers
program for adherence to good manufacturing practices used in the
E 1026 Practice for Using the Fricke Reference Standard
production of safe and wholesome food.
2
Dosimetry System
NOTE 2—ISO/ASTM Practice 51431 describes dosimetric procedures
F 1355 Guide for the Irradiation of Fresh Fruits as a
for electron beam and bremsstrahlung (X-ray) irradiation facilities for
2
food processing. Phytosanitary Treatment
F 1356 Guide for the Irradiation of Fresh and Frozen Red
1.2 For guidance in the selection and calibration of dosim-
Meats and Poultry to Control Pathogens and Other Micro-
eters, and interpretation of measured absorbed dose in the
2
organisms
product, see ISO/ASTM Guide 51261 and ASTM Practice
F 1736 Guide for the Irradiation of Finfish and Shellfish to
E 666. For the use of specific dosimetry systems, see ASTM
2
Control Pathogens and Spoilage Microorganisms
Practices E 668, E 1026 and ISO/ASTM Practices 51205,
2.2 ISO/ASTM Standards:
51275, 51276, 51310, 51401, 51538, 51540, 51607, and
51205 Practice for Use of a Ceric-Cerous Sulfate Dosimetry
51650. For discussion of radiation dosimetry for gamma rays
2
System
and X-rays also see ICRU Report 14.
51261 Guide for Selection and Calibration of Dosimetry
1.3 This standard does not purport to address all of the
2
Systems for Radiation Processing
safety concerns, if any, associated with its use. It is the
51275 Practice for Use of a Radiochromic Film Dosimetry
responsibility of the user of this standard to establish appro-
2
System
priate safety and health practices and determine the applica-
51276 Practice for Use of a Polymethylmethacrylate Do-
bility of regulatory limitations prior to use.
2
simetry System
2. Referenced Documents 51310 Practice for Use of a Radiochromic Optical
2
Waveguide Dosimetry System
2.1 ASTM Standards:
2
51401 Practice for Use of a Dichromate Dosimetry System
E 170 Terminology Relating to Radiation Measurements
2 51431 Practice for Dosimetry in Electron Beam and
and Dosimetry
2
Bremsstrahlung Irradiation Facilities for Food Processing
E 177 Practice for Use of the Terms Precision and Bias in
3 51538 Practice for Use of an Ethanol-Chlorobenzene Do-
ASTM Test Methods
2
simetry System
2
51539 Guide for the Use of Radiation-Sensitive Indicators
51540 Practice for the Use of a Radiochromic Liquid
1
This practice is under the jurisdiction of ASTM Committee E10 on Nuclear
2
Dosimetry System
Technology and Applications and is the direct responsibility of Subcommittee
E10.01 on Dosimetry for Radiation Processing and is also under the jurisdiction of 51607 Practice for the Use of the Alanine-EPR Dosimetry
2
ISO/TC 85/WG 3.
System
Current edition approved Jan. 22, 2002. Published March 15, 2002. Originally
51650 Practice for the Use of a Cellulose Acetate Dosimetry
e1
published as ASTM E 1204 – 87. Last previous edition E 1204–97 . ASTM
2
System
E 1204 - 93 was adopted by ISO in 1998 with the intermediate designation ISO
15554:1998(E). The present International Standard ISO/ASTM 51204:2002(E) is a
51707 Guide for Estimating Uncertainties in Dosimetry for
revision of ISO 15554.
2
Annual Book of ASTM Standards, Vol 12.02.
3 4
Annual Book of ASTM Standards, Vol 14.02. Annual Book of ASTM Standards, Vol 03.06.
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ISO/ASTM 51204:2002(E)
2
Radiation Processing 3.1.8 irradiation time—total time during which a process
2.3 International Commission on Radiation Units and load is exposed to radiation.
Measurements (ICRU) Reports: 3.1.9 primary–standard dosimeter—a dosimeter of the
ICRU Report 14 Radiation Dosimetry: X-Rays and Gamma highest metrological quality, established and maintained as an
Rays with Maximum Photon Energies Between 0.6 and 50 absorbed-dose standard by a national or international standards
5
MeV organization (see ISO/ASTM Guide 51261).
5
ICRU Report 60 Radiation Quantities and Units 3.1.10 process load—a volume of material with a specified
2.4 Codex Alimentarius Commission Reports: loading configuration irradiated as a single entity.
CAC vol. 1, 2nd edition (1992), section 8.1: Recommended 3.1.11 production run (continuous-flow and shuffle-dwell
International Code of Practice for the Operation of Irra- irradiations)—a series of process loads consisting of materials
diation Facilities used for the Treatment of Foods (CAC/ or products having similar radiation-absorption characteristics,
6
RCP 19-1979 (Rev. 1)) that are irradiated sequentially to a specified range of absorbed
dose.
3. Terminology
3.1.12 reference–standard dosimeter—a dosimeter of high
3.1 Definitions—Other terms used in this practice, in addi-
metrological quality, used as a standard to provide measure-
tion to those in 3.1.1-3.1.16, are defined in ASTM Terminology
ments traceable to and consistent with measurements made
E 170 and in ICRU Report 60.
using primary–standard dosimeters (see ISO/ASTM Guide
3.1.1 absorbed dose, D—quantity of ionizing radiation
51261).
energy imparted per unit mass of a specified material. The SI
3.1.13 response function—mathematical representation of
unit of absorbed dose is the gray (Gy), where 1 gray is
the relationship between dosimeter response and absorbed dose
equivalent to the absorption of 1 joule per kilogram of the
for a given dosimetry system.
specified material (1 Gy = 1 J/kg). The mathematical relation-
3.1.14 routine dosimeter—a dosimeter calibrated against a
ship is the quotient of de by dm, where de is the mean
primary-, reference-, or transfer–standard dosimeter and used
incremental energy imparted by ionizing radiation to matter of
for routine absorbed-dose measurements (see ISO/ASTM
incremental mass dm (see ICRU Report 60).
Guide 51261).
3.1.15 simulated product—a mass of material with attenu-
D 5 de/dm (1)
ation and scattering properties similar to those of the product,
3.1.2 absorbed-dose mapping—measurement of the ab-
material or substance to be irradiated.
sorbed dose within a process load using dosimeters placed at
3.1.15.1 Discussion—Simulated product is used during ir-
specified locations to produce a one-, two- or three-
radiator characterization as a substitution for the actual prod-
dimensional distribution of absorbed dose, thus rendering a
uct, material or substance to be irradiated. When used in
map of absorbed-dose values.
routine production runs, it is sometimes referred to as “com-
3.1.3 calibration facility—combination of an ionizing radia-
pensating dummy.” When used for absorbed-dose mapping,
tion source and its associated instrumentation that provides, at
simulated product is sometimes referred to as “phantom
a specified location and within a specific material, a uniform
material.”
and reproducible absorbed dose, or absorbed-dose rate, trace-
3.1.16 transfer–standard dosimeter—a dosimeter, often a
able to national or international standards and that may be used
reference–standard dosimeter, suitable for transport between
to derive the dosimetry system’s response function or calibra-
different locations used to compare absorbed-dose measure-
tion curve.
ments (see ISO/ASTM Guide 51261).
3.1.4 compensating dummy—simulated product used during
routine production runs in process loads that contain less
4. Significance and Use
product than specified in the product loading configuration, or
4.1 Food products may be treated with ionizing radiation,
simulated product used at the beginning or end of a production
60 137
such as gamma rays from Co or Cs sources, for numer-
run, to compensate for the absence of product.
ous purposes, including control of parasites and pathogenic
3.1.5 dosimeter response—the reproducible, quantifiable ra-
microorganisms, insect disinfestation, growth and maturation
diation effect produced by a given absorbed dose.
inhibition, and shelf-life extension. Food irradiation specifica-
3.1.6 dosimeter set—one or more dosimeters used to mea-
tions usually include an upper and lower limit of absorbed
sure the absorbed dose at a location and whose average reading
dose: a minimum to ensure the intended beneficial effect and a
is used as the absorbed-dose measurement of that location.
maximum to avoid product degradation. For a given applica-
3.1.7 dosimetry system—a system used for determining
tion, one or both of these values may be prescribed by
absorbed dose consisting of dosimeters, measurement instru-
regulations that have been established on the basis of available
ments and their associated reference standards, and procedures
scientific data. Therefore, it is necessary to determine the
for the system’s use.
capability of an irradiation facility to process within these
absorbed-dose limits prior to the irradiation of the food
5
Available from the International Commission on Radiation Units and Measure-
product. Once this capability is established, it is necessary to
ments, 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814, USA.
monitor and record the absorbed dose during each production
6
Available from the Joint FAO/WHO Food Standards Program, Joint Office,
run to verify compliance with the process specifications within
Food and Agriculture Organization of the United Nations, Via Della Terme de
Caracalla, 00100 Rome, Italy. a predetermined level of confidence.
© ISO/ASTM International 2002 – All rights reserved
2

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ISO/ASTM 51204:2002(E)
7
NOTE 3—The Codex Alimentarius Commission (1) uses the term
process load or the process load extends beyond the source. In
“overall average absorbed dose” in discussing broad concepts such as the
the latter configuration, the process load is usually moved past
wholesomeness of foods irradiated to an overall average absorbed dose of
the source at two or more different levels. In bulk-flow
less than 10 kGy. The overall average dose should not, however, be used
irradiators, products such as grain or flour flow in loose form
in place of minimum or maximum absorbed doses for specific applica-
past the source.
tions. The CAC confirms this in the following statement from CAC/RCP
6.2 Because of mechanical speed limitations, various tech-
19-1979 Annex A: “The design of the facility and the operational
parameters have to take into account minimum and maximum dose values niques may be used to reduce the absorbed-dose rates for low
required by the process.”
absorbed-dose applications. These techniques include using
NOTE 4—In some countries regulations require that the dose absorbed
only a portion of the source (e.g. raising only one of several
by a food item should not exceed some specified overall average dose in
source racks to the irradiation position), using attenuators, and
addition to minimum and maximum dose values. In this case, the overall
irradiating at greater distances from the source.
averaged dose is the mean value of the lower and upper limits.
6.3 The design of an irradiator affects the delivery of
4.2 Some food products are processed in the chilled or
absorbed dose to a product. Therefore, the irradiator design
frozen state. Therefore, it is necessary to confirm that the
must be considered when performing the absorbed-dose mea-
dosimeters used for routine monitoring are usable at low
surements required in Sections 8, 9, and 10.
temperature and that the dosimeter temperature during irradia-
7. Dosimetry Systems (see ASTM Practice E 1026, ISO/
tion is sufficiently stable to allow correction for temperature
ASTM Practices 51205, 51275, 51276, 51310, 51401,
effects on the dosimeter response.
51538, 51540, 51607, 51650, and ISO/ASTM Guide
4.3 For more detailed discussions of radiation processing of
51261).
various foods, see ASTM Guides F 1355, F 1356, and F 1736
and References (1-10).
7.1 Dosimeter Classes and Applications:
7.1.1 Reference– or Transfer–Standard Dosimeters are
5. Radiation Source Characteristics
used to calibrate radiation fields (environments) and dosimetry
5.1 The radiation source used in a facility considered in this systems employed in routine radiation processing. Reference
60 137
practice consists of sealed elements of Co or Cs which
or transfer dosimeters may also be used as routine dosimeters
are typically linear (rods or “pencils”) arranged in one or more (7.1.2).
planar or cylindrical arrays.
7.1.2 Routine Dosimeters are used for monitoring and qual-
5.2 Cobalt-60 emits photons with energies of approximately ity assurance in food irradiation processing.
1.17 and 1.33 MeV in nearly equal proportions. Cesium-137
7.1.3 Operational and technical criteria for the selection of a
produces photons with energies of approximately 0.662 MeV
dosimetry system are given in ISO/ASTM Guide 51261.
(11).
7.2 Calibration of Dosimetry Systems:
60 137
5.3 The half-lives for Co and Cs are approximately
7.2.1 Prior to use, dosimetry systems shall be calibrated in
5.27 years and 30.2 years, respectively (11). accordance with the user’s documented procedure that speci-
5.4 Between source replenishments, removals, or redistribu-
fies details of the calibration process and quality assurance
tions, the only variation in the source output is the steady requirements. This calibration procedure shall be repeated at
reduction in the activity caused by the radioactive decay.
regular intervals to ensure that the accuracy of the absorbed
dose measurement is maintained within required limits. Irra-
6. Types of Facilities
diation is a critical component of the calibration of the
dosimetry system. Detailed calibration procedures are provided
6.1 Food processing facilities may be categorized by irra-
diator type (for example, container or bulk flow), conveyor in ISO/ASTM Guide 51261.
7.2.2 Calibration Irradiation of Reference or Transfer
system (for example, shuffle-dwell or continuous), and operat-
ing mode (for example, batch or continuous). Food products Dosimeters—Calibration irradiations shall be performed by
irradiating the reference– or transfer—standard dosimeters
may be moved to the location in the facility where the
irradiation will take place, either while the source is fully using a calibration facility that provides an absorbed dose or an
absorbed-dose rate having measurement traceability to nation-
shielded (batch operation) or while the source is exposed
(continuous operation). Food products may be transported past ally or internationally recognized standards.
7.2.3 Calibration Irradiation of Routine Dosimeters—
the source at a uniform and controlled speed (continuous
conveyance), or may instead undergo a series of discrete Calibration irradiations shall be performed in several ways,
including irradiating the routine dosimeters using:
controlled movements separated by controlled time periods
during which the process load is stationary (shuffle-dwell). For 7.2.3.1 A calibration facility that provides an absorbed dose
or an absorbed-dose rate having measurement traceability to
irradiators with rectangular source arrays, the process load
generally makes one or more passes on each side of the source. nationally or internationally recognized standards, or
7.2.3.2 An in-house calibration facility that provides an
Process loads may move past a rectangular source array in a
absorbed dose or an absorbed-dose rate having measurement
configuration in which the source either extends beyond the
traceability to nationally or internationally recognized stan-
dards, or
7
7.2.3.3 A production or research irradiation facility together
The boldface numbers in parentheses refer to the bibliography at the end of this
practice. with reference– or transfer–standard dosimeters that have
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3

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ISO/ASTM 51204:2002(E)
measurement traceability to nationally or internationally rec- any equipment modification or servicing and prior to the use of
ognized standards. the equipment for a dosimetry system calibration. This check
7.2.4 When a reference– or transfer-standard dosimeter is to can be accomplished by using standards such as calibrated
be used as a routine dosimeter, calibration may also be optical density filters, wavelength standards, or calibrated
performed as stated in 7.2.3.2 or 7.2.3.3. thickness gauges supplied by the manufacturer or national or
7.2.5 Instrument Calibration—Calibrations of the indi- accredited standards laboratories.
vidual instruments used in the analysis of the dosimeters shall
8.3.2.2 Implement a documented calibration program to
be verified at periodic intervals. These calibrations shall be assure that all analytical equipment used in the analysis of
traceable to nationally or internationally recognized standards. dosimeters is calibrated periodically.
For example, if an optical absorbance-measuring instrument 8.3.2.3 Prior to each use of an analytical instrument check
such as a spectrophotometer or densitometer is used, then
the zero setting and, if applicable, the full scale reading.
appropriate standards shall be used to verify the accuracy of the 8.4 Irradiator Characterization:
optical absorbance at a specified wavelength(s). See ASTM
8.4.1 The absorbed dose received by any portion of product
Practices E 275, E 925, and E 958. in a process load depends on facility parameters such as the
activity and geometry of the source, the source to product
8. Installation Qualification
distance, and the irradiation geometry, and on processing
8.1 Objective:
parameters such as the irradiation time, the product composi-
8.1.1 Installation qualification includes the concepts of
tion and density, and the product loading configuration.
equipment documentation, testing and calibration as well as
8.4.2 The absorbed-dose rate and absorbed-dose distribu-
irradiator characterization.
tion in the product will change during movement of the process
8.1.2 The purpose of dosimetry in qualifying a gamma
load. Therefore, a direct scaling from one absorbed dose to
irradiation facility is to establish baseline data for evaluating
another by simply changing the timer setting may not be valid
facility effectiveness, predictability, and reproducibility for the
and this effect should be considered during process qualifica-
range of conditions of operation. For example, dosimetry shall
tion (see Section 9).
be used (1) to establish relationships between the absorbed
8.4.3 To ensure that product near the source is processed
dose for a reproducible geometry and the operating parameters
within specifications, contributions to the absorbed dose in the
of the facility, (2) to characterize absorbed-dose variations
product during movement of the source to and from the
when facility and processing parameters fluctuate statistically
irradiation position should be considered and quantified.
and through normal operations, and (3) to measure absorbed-
8.4.4 The irradiator characterization process shall include
dose distributions in reference materials.
mapping the absorbed-dose distributions in process loads
8.2 Equipment Documentation:
containing actual or simulated product (see 9.2). Dosimetry
8.2.1 Establish and document an irradiator qualification
data from previously characterized irradiators of the same
program to demonstrate that the irradiator, operating within
design or theoretical calculations may provide useful informa-
specified limits, will consistently produce an absorbed-dose
tion for determining the number and location of dosimeters for
distribution in a given product to a predetermined specification.
this characterization process.
Documentation shall be retained for the life of the irradiator
NOTE 5—Theoretical calculations may be performed using the Monte
and shall include descriptions of instrumentation and equip-
Carlo method (13) or the point-kernel method (14). In the point-kernel
ment for ensuring the reproducibility, within specified limits, of
method, the radiation source is approximated by differential isotropic
the source-to-product geometry and the time the product
point sources. The total absorbed dose at each dose point is obtained by
spends at different locations in the irradiation zone (12).
summing the absorbed-dose contribution from each isotropic source point.
8.3 Equipment Testing and Calibration:
The absorbed dose at a dose point depends mainly on the energy of the
8.3.1 Processing Equipment—The absorbed dose in the gamma radiation and the composition (for example, density and thickness)
of the materials surrounding and located between the source point and
product in a process load depends on the operating parameters
dose point (for example, source encapsulation material, other product
of the irradiation facility which are controlled by the process-
units, and carrier wall material). In the Monte Carlo method, the total
ing equipment and instrumentation.
absorbed dose at a dose point is determined from the energy distribution
8.3.1.1 Test all processing equipment and instrumentation
at that point by modeling the trajectories of photons and electrons through
that may influence absorbed dose in order to verify satisfactory
the absorbing media. In order to obtain a good statistical representation of
operation of the irradiator within the design specifications. their interactions (for example, scattering or absorption) within the media,
the paths of a sufficiently large number of photons and electrons are
8.3.1.2 Implement a documented calibration program to
followed until the dose point is reached. Like the point-kernel method, the
assure that all processing equipment and instrumentation that
Monte Carlo method requires a knowledge of all materials between and
may influence absorbed dose are calibrated periodically.
surrounding the source point and dose point.
8.3.2 Analytical Equipment—The accuracy of the absorbed-
dose measurement depends on the correct operation and 8.
...