ISO/ASTM 51939:2017

Practice for blood irradiation dosimetry

1.1 This practice outlines the irradiator installation qualifi-cation program and the dosimetric procedures to be followed during operational qualification and performance qualification of the irradiator. Procedures for the routine radiation process-ing of blood product (blood and blood components) are also given. If followed, these procedures will help ensure that blood product exposed to gamma radiation or X-radiation (bremsstrahlung) will receive absorbed doses with a specified range. 1.2 This practice covers dosimetry for the irradiation of blood product for self-contained irradiators (free-standing irradiators) utilizing radionuclides such as 137Cs and 60Co, or X-radiation (bremsstrahlung). The absorbed dose range for blood irradiation is typically 15 Gy to 50 Gy. 1.3 The photon energy range of X-radiation used for blood irradiation is typically from 40 keV to 300 keV. 1.4 This practice also covers the use of radiation-sensitive indicators for the visual and qualitative indication that the product has been irradiated (see ISO/ASTM Guide 51539). 1.5 ISO 51939:2017 is one of a set of standards that provides recommendations for properly implementing dosimetry in radiation processing and describes a means of achieving compliance with the requirements of ISO/ASTM Practice 52628 for dosimetry performed for blood irradiation. It is intended to be read in conjunction with ISO/ASTM Practice 52628. 1.6 ISO 51939:2017 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 appro-priate safety and health practices and to determine the applicability or regulatory limitations prior to use.

Pratique de la dosimétrie pour l'irradiation du sang

General Information

• Status: Published
• Publication Date: 05-Mar-2017
• ICS: 11.020 - Medical sciences and health care facilities in general
• ICS: 11.020.99 - Other standards related to health care in general
• 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: 28-Sep-2022

Relations

• Revises: ISO/ASTM 51939:2013 - Practice for blood irradiation dosimetry
• Effective Date: 26-Mar-2016

Standards Content (Sample)

INTERNATIONAL ISO/ASTM
STANDARD 51939
Fourth edition
2017-02
Practice for blood irradiation
dosimetry
Pratique de la dosimétrie pour l’irradiation du sang
Reference number
ISO/ASTM 51939:2017(E)
©
ISO/ASTM International 2017

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ISO/ASTM 51939:2017(E)

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ii © ISO/ASTM International 2017 – All rights reserved

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ISO/ASTM 51939:2017(E)
Explanatory Material
This international standard is part of the project between ISO and ASTM International to develop and
maintain a group of ISO/ASTM dosimetry standards for radiation processing. In accordance with ISO/TC
85 N 1248, Maintenance Procedures for ISO/ASTM Radiation Processing Dosimetry Standards, a joint
meeting of ISO/TC 85 WG3 Dosimetry for Radiation Processing and ASTM Committee E61 was held in
New Orleans, Louisiana, on January 16-28 to review standards being considered for withdrawal, revision/
amendment, or confirmation. Although ISO/ASTM 51939, published in 2005, had been reapproved in 2013,
it was decided that this standard should be revised to bring it in line with the new format adopted for the
ISO/ASTM standards. A review was conducted to determine if, in addition to the format changes, technical
changes would be required. From this review it was decided that major changes should be made to the
standard and that it should be revised as a major revision.
The new standard covers the irradiation of blood or blood components in self-contained blood irradiators
using photons. The previous version also covered the use of teletherapy equipment and electron beams.
The standard provides recommendations for properly implementing dosimetry in blood irradiation. The
practice describes a means of achieving compliance with the requirments of ISO/ASTM Practice 52628 for
dosimetry performed for blood irradiation and is intended to be read in conjunction with ISO/ASTM 52628.
ii-2
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ISO/ASTM 51939:2017(E)
Contents Page
1 Scope. 1
2 Referenced documents. 1
3 Terminology. 2
4 Significance and use. 3
5 Type of irradiators and modes of operation. 4
6 Radiation source characteristics. 4
7 Dosimetry systems. 5
8 Installation qualification. 6
9 Operational qualification. 6
10 Performance qualification. 7
11 Routine product processing . 8
12 Maintenance of validation. 9
13 Measurement uncertainty. 9
14 Keywords. 9
Annexes. 10
Table 1 Examples of reference-standard dosimetry systems. 5
Table 2 Examples of routine dosimetry systems. 6
Table A2.1 Recommended quality assurance steps for blood irradiation. 12
iii
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ISO/ASTM 51939:2017(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 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 Commitee 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 51939 was developed by ASTM Committee E61, Radiation Processing,
through Subcommittee E61.04, Specialty Application, and by Technical Committee ISO/TC 85, Nuclear
energy, nuclear technologies and radiological protection.
This fourth edition cancels and replaces the third edition (ISO/ASTM 51939:05(2013)), which has been
technically revised.
iv
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ISO/ASTM 51939:2017(E)
Standard Practice for
1
Blood Irradiation Dosimetry
ThisstandardisissuedunderthefixeddesignationISO/ASTMFDIS51939;thenumberimmediatelyfollowingthedesignationindicates
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 outlines the irradiator installation qualifi-
2.1 ASTM Standards:
cation program and the dosimetric procedures to be followed
E170Terminology Relating to Radiation Measurements and
during operational qualification and performance qualification
Dosimetry
of the irradiator. Procedures for the routine radiation process-
2
2.2 ISO/ASTM Standards:
ing of blood product (blood and blood components) are also
51026Practice for Using the Fricke Dosimetry System
given.Iffollowed,theseprocedureswillhelpensurethatblood
51261Practice for Calibration of Routine Dosimetry Sys-
product exposed to gamma radiation or X-radiation
tems for Radiation Processing
(bremsstrahlung) will receive absorbed doses with a specified
51275 Practice for Use of a Radiochromic Film Dosimetry
range.
System
1.2 This practice covers dosimetry for the irradiation of
51310Practice for Use of a Radiochromic Optical Wave-
blood product for self-contained irradiators (free-standing
137 60
guide Dosimetry System
irradiators) utilizingradionuclides such as Cs and Co, or
51539Guide for the Use of Radiation-Sensitive Indicators
X-radiation (bremsstrahlung). The absorbed dose range for
51607Practice for Use of the Alanine-EPR Dosimetry Sys-
blood irradiation is typically 15 Gy to 50 Gy.
tem
1.3 The photon energy range of X-radiation used for blood
51707Guide for Estimating Uncertainties in Dosimetry for
irradiation is typically from 40 keV to 300 keV.
Radiation Processing
1.4 This practice also covers the use of radiation-sensitive
51956Practice for Use of Thermoluminescence-Dosimetry
indicators for the visual and qualitative indication that the
Systems (TLD Systems) for Radiation Processing
product has been irradiated (see ISO/ASTM Guide 51539).
52116Practice for Dosimetry for a Self-Contained Dry-
1.5 This document is one of a set of standards that provides
Storage Gamma-Ray Irradiator
recommendations for properly implementing dosimetry in
52628Practice for Dosimetry in Radiation Processing
radiation processing and describes a means of achieving
52701Guide for Performance Characterization of Dosim-
compliance with the requirements of ISO/ASTM Practice
eters and Dosimetry Systems for Use in Radiation Pro-
52628 for dosimetry performed for blood irradiation. It is
cessing
intended to be read in conjunction with ISO/ASTM Practice
2.3 International Commission on Radiation Units and Mea-
52628.
3
surements Reports (ICRU):
1.6 This standard does not purport to address all of the
ICRU 80Dosimetry Systems for Use in Radiation Process-
safety concerns, if any, associated with its use. It is the
ing
responsibility of the user of this standard to establish appro-
ICRU 85aFundamental Quantities and Units for Ionizing
priate safety and health practices and to determine the
Radiation
applicability or regulatory limitations prior to use.
1
This practice is under the jurisdiction of ASTM Committee E61 on Radiation
2
Processing and is the direct responsibility of Subcommittee E61.04 on Specialty For referenced ASTM and ISO/ASTM standards, visit the ASTM website,
Application, and is also under the jurisdiction of ISO/TC 85/WG 3. www.astm.org, or contact ASTM Customer Service at [e-mail]. For
Current edition approved by ASTM Jan. 1, 2016. Published XX. Originally Annual Book of ASTM Standards volume information, refer to the standard’s
published as ASTM E 1939–98. Last previous ASTM edition E 1939–98. The Document Summary page on the ASTM website.
3
present International Standard ISO/ASTM 51939:2016(E) is a revision of the last Available from the International Commission on Radiation Units and
previous edition ISO/ASTM 51939:05(2013)(E). Measurements, 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814 U.S.A.
© ISO/ASTM International 2017 – All rights reserved
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ISO/ASTM 51939:2017(E)
4
2.4 ISO Standards: three-dimensionaldistributionofabsorbeddose,thusrendering
12749-4Nuclear energy – Vocabulary – Part 4: Dosimetry a map of absorbed-dose values.
for radiation processing 3.1.3.1 Discussion—Forabloodcanister,suchadosemapis
4
obtained using dosimeters placed at specified locations within
2.5 ISO/IEC Standards:
the canister.
17025General Requirements for the Competence ofTesting
and Calibration Laboratories 3.1.4 activity (A) (of an amount of radionuclide in a
particular energy state at a given time)—quotientof–dNbydt,
2.6 Guidelines on Blood Irradiation:
where dN is the mean change in the number of nuclei in that
Guidelines on the Use of Irradiated Blood Components
energy state due to spontaneous nuclear transitions in the time
(2013),Prepared by the BCSH Blood Transfusion Task
5
interval dt (see ICRU 85a).
Force
Recommendations Regarding License Amendments and
A52dN/dt (3)
Procedures for Gamma Irradiation of Blood Products,
−1
Unit: s
6
(1993)US Food and Drug Administration
The special name for the unit of activity is the becquerel
Guidance for Industry,Gamma Irradiation of Blood and
−1
(Bq). 1 Bq=1s .
BloodComponents:APilotProgramforLicensing(2000)
6 3.1.4.1 Discussion—
US Food and Drug Administration
(1)The former special unit of activity was the curie (Ci).
2.7 Joint Committee for Guides in Metrology (JCGM) 10 −1
1Ci=3.7×10 s (exactly).
Reports:
(2)The ‘particular energy state’ is the ground state of the
JCGM100:2008GUM1995,withminorcorrections,Evalu-
nuclide unless otherwise specified.
ation of measurement data – Guide to the expression of
(3)Theactivityofanamountofradionuclideinaparticular
7
uncertainty in measurement
energystateisequaltotheproductofthedecayconstant, λ,for
JCGM 200:2012 (JCGM 200:2008 with minor revisions),
thatstateandthenumberofnucleiinthatstate(thatis, A=Nλ).
VIM,International vocabulary of metrology – Basis and
8 3.1.5 approved laboratory—laboratory that is a recognized
general concepts and associated terms
nationalmetrologyinstitute;orhasbeenformallyaccreditedto
ISO/IEC 17025; or has a quality system consistent with the
3. Terminology
requirements of ISO/IEC 17025.
3.1 Definitions:
3.1.5.1 Discussion—A recognized national metrology insti-
3.1.1 absorbed dose (D)—quotient of dɛ¯ by dm, where dɛ¯ is
tute or other calibration laboratory accredited to ISO/IEC
the mean energy imparted by ionizing radiation to matter of
17025 should be used in order to ensure traceability to a
mass dm (see ICRU 85a).
national or international standard. A calibration certificate
provided by a laboratory not having formal recognition or
D5dε¯/dm (1)
3.1.1.1 Discussion—TheSIunitofabsorbeddoseisthegray accreditation will not necessarily be proof of traceability to a
(Gy),where1grayisequivalenttotheabsorptionof1jouleper national or international standard.
kilogram of the specified material (1 Gy = 1 J/kg).
3.1.6 bremsstrahlung—broad-spectrum electromagnetic ra-
˙
3.1.2 absorbed-dose rate (D)—quotient of dD by dt, where diation emitted when an energetic charged particle is influ-
dD is the increment of absorbed dose in the time interval dt,
enced by a strong electric or magnetic field, such as that in the
thus vicinity of an atomic nucleus.
3.1.6.1 Discussion—
˙
D5dD/dt (2)
(1)In radiation processing, bremsstrahlung photons with
–1
3.1.2.1 Discussion—The SI unit is Gy·s . However, the
sufficient energy to cause ionization are generated by the
absorbed-dose rate is often specified in terms of its average
deceleration or deflection of energetic electrons in a target
value over longer time intervals, for example, in units of
material. When an electron passes close to an atomic nucleus,
–1 –1
Gy·min or Gy·h .
the strong coulomb field causes the electron to deviate from its
3.1.3 absorbed-dose mapping—measurement of absorbed
original motion. This interaction results in a loss of kinetic
dose within an irradiated product to produce a one, two, or
energy by the emission of electromagnetic radiation. Since
such encounters are uncontrolled, they produce a continuous
photon energy distribution that extends up to the maximum
4
Available from International Organization for Standardization (ISO), ISO
kinetic energy of the incident electron.
Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier,
(2)The bremsstrahlung spectrum depends on the electron
Geneva, Switzerland, http://www.iso.org.
5 energy, the composition and thickness of the target, and the
Available from the National Blood Transfusion Service, East Anglian Blood
Transfusion Centre, Long Road, Cambridge, CB2 2PT United Kingdom. angle of emission with respect to the incident electron.
6
Available from the Office of Communication, Training and Manufacturers
3.1.7 calibration—set of operations that establish under
Assistance (HFM-40), 1401 Rockville Pike, Rockville, MD 20852-1488, USA.
7
specified conditions, the relationship between values of quan-
Document produced by working Group 1 of the Joint Committee for Guides in
Metrology (JCGM WG1). Available free of charage at the BIPM website (http://
tities indicated by a measuring instrument or measuring
www.bipm.org).
system, or values represented by a material measure or a
8
Document produced by working Group 2 of the Joint Committee for Guides in
reference material, and the corresponding values realized by
Metrology (JCGM WG2). Available free of charge at the BIPM website (http://
www.bipm.org). standards.
2 © ISO/ASTM International 2017 – All rights reserved

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ISO/ASTM 51939:2017(E)
3.1.7.1 Discussion—Calibration conditions include environ- 3.1.20 simulated product—material with radiation absorp-
mental and irradiation conditions present during irradiation, tion and scattering properties similar to those of the product,
storage and measurement of the dosimeters that are used for the material or substance to be irradiated.
generation of a calibration curve.
3.1.20.1 Discussion—
(1)Simulated product is used during irradiator character-
3.1.8 dosimeter—device that, when irradiated, exhibits a
ization as a substitute for the actual product, material or
quantifiable change that can be related to absorbed dose in a
substance to be irradiated.
given material using appropriate measurement instruments and
(2)When used in routine production runs in order to
procedures.
compensate for the absence of product, simulated product is
3.1.9 dosimeter batch—quantity of dosimeters made from a
sometimes referred to as compensating dummy.
specific mass of material with uniform composition, fabricated
(3)When used for absorbed-dose mapping, simulated
in a single production run under controlled, consistent condi-
product is sometimes referred to as phantom material.
tions and having a unique identification code.
3.1.21 timer setting—defined time interval during which
3.1.10 dosimetry system—system used for measuring ab-
product is exposed to radiation.
sorbed dose, consisting of dosimeters, measurement instru-
ments and their associated reference standards, and procedures
3.1.22 transfer-standard dosimetry system—dosimetry sys-
for the system’s use. tem used as an intermediary to calibrate other dosimetry
systems.
3.1.11 installation qualification (IQ)—process of obtaining
and documenting evidence that equipment has been provided
3.1.23 transit dose—absorbed dose delivered to a product
and installed in accordance with specifications.
(or a dosimeter) while it travels between the non-irradiation
position and the irradiation position, or in the case of a
3.1.12 irradiator turntable—device used to rotate the
movable source while the source moves into and out of its
sample during the irradiation process so as to improve dose
irradiation position.
uniformity.
3.1.12.1 Discussion—An irradiator turntable is often re-
3.1.24 validation—documented procedure for obtaining, re-
ferred to as a turntable. Some irradiator geometries, for
cording and interpreting the results to establish that a process
example with a circular array of radiation sources surrounding
will consistently yield product complying with predetermined
the product, may not need a turntable.
specifications.
3.1.13 isodose curves—lines or surfaces of constant ab-
3.1.25 X-radiation—ionizing electromagnetic radiation
sorbed dose through a specified medium.
which includes both bremsstrahlung and the characteristic
radiation emitted when atomic electrons make transitions to
3.1.14 measurement management system—set of interre-
lated or interacting elements necessary to achieve metrological more tightly bound states.
confirmation and continual control of measurement processes.
3.1.25.1 Discussion—In radiation processing applications
(suchasbloodproductirradiation),theprincipalX-radiationis
3.1.15 operational qualification (OQ)—process of obtaining
bremmstrahlung.
and documenting evidence that installed equipment operates
within predetermined limits when used in accordance with its
3.1.26 X-ray converter—device for generating X-radiation
operational procedures.
(bremsstrahlung)fromanelectronbeam,consistingofatarget,
means for cooling the target, and a supporting structure.
3.1.16 performance qualification (PQ)—process of obtain-
ing and documenting evidence that the equipment as installed
3.2 Definitions of Terms Specific to This Standard:
and operated in accordance with operational procedures, con-
3.2.1 blood product (blood and blood components)—whole
sistently performs in accordance with predetermined criteria
blood, red cells, frozen cells, platelet concentrates, apheresis
and thereby yields product that meeting its specification.
platelets,granulocyteconcentrates,andfreshorfrozenplasma.
3.1.17 radiation-sensitive indicator—material such as a
3.2.1.1 Discussion—Enclosure systems for blood and blood
coated or impregnated adhesive-backed substrate, ink, coating
components are commonly referred to as “bags.”
or other material which may be affixed to or printed on the
3.2.2 canister—containerusedtohousethebloodproductor
product and which undergoes a visual change when exposed to
blood-equivalent product during the irradiation process.
ionizing radiation.
3.1.17.1 Discussion—Radiation-sensitive indicators are of-
3.3 Definitions of other terms used in this standard that
ten referred to as “indicators.”
pertain to radiation measurement and dosimetry may be found
in ISO 12749-4, ASTM Terminology E170, ICRU 85a and
3.1.18 reference-standard dosimetry system—dosimetry
VIM; these documents, therefore, may be used as alternative
system, generally having the highest metrological quality
references.
available at a given location or in a given organization, from
which measurements made there are derived.
4. Significance and use
3.1.19 routine dosimetry system—dosimetry system cali-
brated against a reference standard dosimetry system and used 4.1 Blood and blood components are irradiated to predeter-
for routine absorbed-dose measurements, including dose map- mined absorbed doses to inactivate viable lymphocytes to help
ping and process monitoring. prevent transfusion-induced graft-versus-host disease (GVHD)
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ISO/ASTM 51939:2017(E)
units containing radionuclides usually have a mechanism to
in certain immunocompromised patients and those receiving
9
move the canister from the load/unload position to the irradia-
related-donor products (1, 2).
tion position.
4.2 The assurance that blood and blood components have
5.1.1 Somecommonmethodsusedforimprovingabsorbed-
been properly irradiated is of crucial importance for patient
dose uniformity in the blood product are to either rotate the
health. This shall be demonstrated by means of accurate
canister holding the blood product in front of the radiation
absorbed-dose measurements on the product, or in simulated
source or to have multiple sources irradiating the product from
product.
different directions.
4.3 Blood and blood components are usually irradiated
137 60
using gamma radiation from Cs or Co sources, or
6. Radiation source characteristics
X-radiation from X-ray units.
6.1 Gamma Irradiators:
4.4 Blood irradiation specifications include a lower limit of
6.1.1 The source of gamma radiation used in the irradiators
absorbeddose,andmayincludeanupperlimitorcentraltarget
60 137
considered in this practice consists of sealed Co or Cs
dose. For a given application, any of these values may be
radionuclides that are typically linear rods arranged in one or
prescribed by regulations that have been established on the
more planar or annular arrays.
basis of available scientific data (see 2.6).
6.1.2 Cobalt-60 emits photons with energies of approxi-
4.5 For each blood irradiator, an absorbed-dose rate at a
mately 1.17 and 1.33 MeV in nearly equal proportions.
reference position within the canister is measured as part of
Cesium-137 produces photons with energies of approximately
irradiator acceptance testing using a reference-standard dosim-
0.662 MeV.
etry system. That reference-standard measurement is used to
60 137
6.1.3 The radioactive decay half-lives for Co and Cs
establishoperatingparameterssoastodeliverspecifieddoseto
are regularly reviewed and updated. The most recent publica-
blood and blood components.
tion by the National Institute of Standards and Technology
4.6 Absorbed-dose measurements are performed within the
60
gave values of 1925.20 (60.25) days for Co and 11018.3
blood or blood-equivalent volume for determining the
137
(69.5) days for Cs (4).
absorbed-dose distribution. Such measurements are often per-
6.1.4 For gamma sources, the only variation in the source
formed using simulated product (for example, polystyrene is
137
output is the known reduction in the activity caused by
considered blood equivalent for Cs photon energies).
radioactive decay. This reduction in the source output and the
4.7 Dosimetryispartofameasurementmanagementsystem
required increase in the irradiation time to deliver the same
that is applied to ensure that the radiation process meets
dose may be calculated (see 10.4.2) or obtained from tables
predetermined specifications (see ISO/ASTM Practice 52628).
provided by the irradiator manufacturer.
4.8 Blood and blood components are usually irradiated in
6.2 X-ray Irradiators,
chilled or frozen condition. Care should be taken, therefore, to
6.2.1 Low energy X-ray irradiators use X-ray tubes that
ensure that the dosimeters and radiation-sensitive indicators
consist of an electron source (generally a heated wire, a
can be used under such temperature conditions.
filament which emits electrons), an electrostatic field to accel-
4.9 Proper documentation and record keeping are critical
erate these electrons, and a converter to generate X-radiation.
components of a radiation process. Documentation and record
6.2.2 An X-ray (bremsstrahlung) irradiator emits short-
keeping requirements may be specified by regulatory authori-
wavelength electromagnetic radiation, which is analogous to
ties or may be given in the corporation’s quality policy.
gamma radiation from radioactive sources. Although their
4.10 Response of most dosimeters has significant energy
effectsonirradiatedmaterialsaregenerallysimilar,thesekinds
dependence at photon energies of less than 100 keV, so proper
of radiation differ in their energy spectra (see 6.2.3), angular
care must be exercised when measuring absorbed dose in that
distribution, and dose rates. The physical characteristics of the
energy range.
X-radiation (bremsstrahlung) field depend on the design of the
X-ray tube.
5. Type of irradiators and modes of operation
6.2.3 Currently available low-energy X-ray irradiators gen-
5.1 Self-contained irradiators expose samples to gamma
erate X-radiation with a maximum energy of 160 keV. The
137 60
irradiation produced by isotopes of either Cs or Co (3)
spectrum of the X-ray energy extends from the maximum
(ISO/ASTM Practice 52116), or to low energy X-radiation
energy to approximately 30 keV.
(bremsstrahlung) produced by an X-ray tube.These irradiators
6.2.4 The energy of the X-radiation influences the size and
house their radiation source in a protective lead shield or other
shape of the canister needed to achieve the desired level of
appropriate high atomic number material in accordance with
doseuniformityinthebloodcanister.Filtersareusedtoreduce
the safety requirements. Currently available units using low-
the low-energy components to improve dose uniformity in the
energyX-radiation(bremsstrahlung)requirelessshieldingthan
canister. These filters may form part of the X-ray tube or may
units containing gamma-emitting radioactive isotopes. Such
be material added to the irradiator or canister. Reflectors may
also be used to improve the dose uniformity.
9 6.2.5 The absorbed-dose rate and thus time of irradiation is
Theboldfacenumbersinparenthesesrefertothebibliographyattheendofthis
standard. determined by the tube current.
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ISO/ASTM 51939:2017(E)
7. Dosimetry systems tainty achievable with measurements made using a reference
standard dosimetry system is typically of the order of3%(at
7.1 Description of Dosimeters and Dosimetry Systems—
the 95 % confidence level).
Classificationofdosimetersanddosimetrysystemsisbasedon
(4)Examples of reference standard dosimetry systems are
the inherent metrological dosimeter properties and the field of
given in Table 1.
application of the dosimetry system (see ISO/ASTM Practice
52628). These classifications influence both the selection and
7.1.2.2 Routine Dosimetry Systems:
calibration of dosimetry systems.
(1)The classification of a dosimetry system as a routine
7.1.1 Classification of Dosimeters—Classificationofdosim-
dosimetry system is based on its application, that is, routine
eters is based on their inherent metro
...