ASTM ISO/ASTM51939-22

Standard Practice for Blood Irradiation Dosimetry

SIGNIFICANCE AND USE
4.1 Blood and blood components are irradiated to predetermined absorbed doses to inactivate viable lymphocytes to help prevent transfusion-induced graft-versus-host disease (GVHD) in certain immunocompromised patients and those receiving related-donor products (1, 2).9  
4.2 The assurance that blood and blood components have been properly irradiated is of crucial importance for patient health. This shall be demonstrated by means of accurate absorbed-dose measurements on the product, or in simulated product.  
4.3 Blood and blood components are usually irradiated using gamma radiation from 137Cs or 60Co sources, or X-radiation from X-ray units.  
4.4 Blood irradiation specifications include a lower limit of absorbed dose, and may include an upper limit or central target dose. For a given application, any of these values may be prescribed by regulations that have been established on the basis of available scientific data (see 2.6).  
4.5 For each blood irradiator, an absorbed-dose rate at a reference position within the canister is measured as part of irradiator acceptance testing using a reference-standard dosimetry system. That reference-standard measurement is used to establish operating parameters so as to deliver specified dose to blood and blood components.  
4.6 Absorbed-dose measurements are performed within the blood or blood-equivalent volume for determining the absorbed-dose distribution. Such measurements are often performed using simulated product (for example, polystyrene is considered blood equivalent for 137Cs photon energies).  
4.7 Dosimetry is part of a measurement management system that is applied to ensure that the radiation process meets predetermined specifications (see ISO/ASTM Practice 52628).  
4.8 Blood and blood components are usually irradiated in chilled or frozen condition. Care should be taken, therefore, to ensure that the dosimeters and radiation-sensitive indicators can be used under such temperature conditions.  
4.9 Proper ...
SCOPE
1.1 This practice outlines the irradiator installation qualification program and the dosimetric procedures to be followed during operational qualification and performance qualification of the irradiator. Procedures for the routine radiation processing 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 This document 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 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides ...

General Information

• Status: Published
• Publication Date: 30-Nov-2022
• ICS: 11.040.20 - Transfusion, infusion and injection equipment
• ICS: 17.240 - Radiation measurements
• Technical Committee: E61 - Radiation Processing
• Drafting Committee: E61.04 - Specialty Application

Relations

• Replaces: ASTM ISO/ASTM51939-17(2022) - Standard Practice for Blood Irradiation Dosimetry
• Effective Date: 01-Dec-2022

Overview

ASTM ISO/ASTM51939-22: Standard Practice for Blood Irradiation Dosimetry is a globally recognized document that outlines best practices for the dosimetry associated with the irradiation of blood and blood components. Issued by ASTM, this standard ensures that blood irradiation processes meet strict safety and quality requirements, primarily aiming to inactivate viable lymphocytes and prevent transfusion-induced graft-versus-host disease (GVHD) in vulnerable patient populations. The standard covers dosimetric qualification programs, calibration, installation, and quality assurance for irradiators using radionuclides such as Cesium-137 (137Cs), Cobalt-60 (60Co), or X-ray units.

Key Topics

• Purpose of Blood Irradiation: Blood and blood components must be exposed to precise absorbed radiation doses to inactivate lymphocytes and reduce GVHD risk in immunocompromised patients or recipients of related-donor transfusions.
• Importance of Accurate Dosimetry: Assuring that irradiation is performed correctly is critical for patient health and regulatory compliance. Proper documentation and measurement of absorbed dose must be maintained.
• Types of Irradiators: The standard details the use of self-contained gamma irradiators (often utilizing 137Cs or 60Co) as well as X-ray (bremsstrahlung) units within a typical photon energy range of 40 keV to 300 keV.
• Dose Specifications: Blood irradiation protocols require a controlled dose, usually between 15 Gy and 50 Gy, with lower and possibly upper dose limits stipulated by scientific data or regulation.
• Dosimetry Systems: The practice distinguishes between reference-standard dosimetry systems (used for calibration) and routine dosimetry systems (used for process monitoring and dose mapping). It includes the requirement for calibration traceable to national or international standards.
• Indicators and Monitoring: Use of radiation-sensitive indicators is included for visual confirmation of irradiation. Regular absorbed-dose mapping and monitoring of the irradiation process are called for.
• Environmental Considerations: Dosimeters and indicators must function reliably under chilled or frozen temperatures, as blood products are commonly irradiated in these conditions.
• Quality and Documentation: The standard underlines the importance of robust measurement management, installation qualification, operational and performance qualification, and documentation of all processes.

Applications

Hospitals, Blood Banks, and Transfusion Services

• Patient Safety: Ensures irradiated blood and blood components consistently receive the prescribed dose to prevent GVHD, thereby enhancing transfusion safety for at-risk patients.
• Regulatory Compliance: Meets regulatory expectations by documenting and controlling irradiation processes, as required by professionals in transfusion medicine.
• Quality Control: Provides a framework for ongoing equipment calibration, operational qualification, and periodic performance evaluation to maintain process integrity.

Medical Device Manufacturers

• Irradiator Qualification: Guides installation and operational qualification protocols for new or existing blood irradiators.
• Product Documentation: Assists manufacturers in developing compliant documentation and processes in accordance with international dosimetry standards.

Accreditation and Inspection

• Traceability: Promotes laboratory practices that are traceable to national or international measurement standards.
• Audit Readiness: Ensures all activities, from dosimeter calibration to absorbed-dose mapping and recordkeeping, are auditable and meet international best practices.

Related Standards

For comprehensive quality management and regulatory compliance in blood irradiation dosimetry, the following standards and guides are frequently referenced:

• ISO/ASTM 52628: Dosimetry in Radiation Processing - General requirements and compliance.
• ISO/ASTM 51026: Practice for Using the Fricke Dosimetry System.
• ISO/ASTM 51539: Guide for the Use of Radiation-Sensitive Indicators.
• ISO/ASTM 51956: Practice for Use of Thermoluminescence-Dosimetry Systems (TLD Systems) for Radiation Processing.
• ISO/ASTM 52116: Dosimetry for Self-Contained Dry-Storage Gamma-Ray Irradiators.
• ISO/IEC 17025: General requirements for the competence of testing and calibration laboratories.

ASTM ISO/ASTM51939-22 is an essential tool for healthcare providers, quality assurance professionals, and regulatory authorities seeking to ensure safe, effective, and standardized blood irradiation practices worldwide. Leveraging these guidelines helps protect patient health, demonstrate compliance, and uphold the highest standards in blood product processing.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: 51939 − 22
Standard Practice for
Blood Irradiation Dosimetry
This standard is issued under the fixed designation 51939; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
1.1 This practice outlines the irradiator installation qualifi-
Barriers to Trade (TBT) Committee.
cation program and the dosimetric procedures to be followed
during operational qualification and performance qualification
2. Referenced documents
of the irradiator. Procedures for the routine radiation process-
ing of blood product (blood and blood components) are also 2
2.1 ASTM Standards:
given. If followed, these procedures will help ensure that blood
E170 Terminology Relating to Radiation Measurements and
product exposed to gamma radiation or X-radiation
Dosimetry
(bremsstrahlung) will receive absorbed doses with a specified
2.2 ISO/ASTM Standards:
range.
51026 Practice for Using the Fricke Dosimetry System
1.2 This practice covers dosimetry for the irradiation of
51261 Practice for Calibration of Routine Dosimetry Sys-
blood product for self-contained irradiators (free-standing
tems for Radiation Processing
137 60
irradiators) utilizing radionuclides such as Cs and Co, or
51275 Practice for Use of a Radiochromic Film Dosimetry
X-radiation (bremsstrahlung). The absorbed dose range for
System
blood irradiation is typically 15 Gy to 50 Gy.
51310 Practice for Use of a Radiochromic Optical Wave-
1.3 The photon energy range of X-radiation used for blood
guide Dosimetry System
irradiation is typically from 40 keV to 300 keV.
51539 Guide for the Use of Radiation-Sensitive Indicators
51607 Practice for Use of the Alanine-EPR Dosimetry Sys-
1.4 This practice also covers the use of radiation-sensitive
tem
indicators for the visual and qualitative indication that the
product has been irradiated (see ISO/ASTM Guide 51539). 51707 Guide for Estimating Uncertainties in Dosimetry for
Radiation Processing
1.5 This document is one of a set of standards that provides
51956 Practice for Use of Thermoluminescence-Dosimetry
recommendations for properly implementing dosimetry in
Systems (TLD Systems) for Radiation Processing
radiation processing and describes a means of achieving
52116 Practice for Dosimetry for a Self-Contained Dry-
compliance with the requirements of ISO/ASTM Practice
Storage Gamma-Ray Irradiator
52628 for dosimetry performed for blood irradiation. It is
52628 Practice for Dosimetry in Radiation Processing
intended to be read in conjunction with ISO/ASTM Practice
52701 Guide for Performance Characterization of Dosim-
52628.
eters and Dosimetry Systems for Use in Radiation Pro-
1.6 This standard does not purport to address all of the
cessing
safety concerns, if any, associated with its use. It is the
2.3 International Commission on Radiation Units and Mea-
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter- surements Reports (ICRU):
ICRU 80 Dosimetry Systems for Use in Radiation Process-
mine the applicability of regulatory limitations prior to use.
1.7 This international standard was developed in accor- ing
dance with internationally recognized principles on standard- ICRU 85a Fundamental Quantities and Units for Ionizing
ization established in the Decision on Principles for the Radiation
This practice is under the jurisdiction of ASTM Committee E61 on Radiation
Processing and is the direct responsibility of Subcommittee E61.04 on Specialty For referenced ASTM and ISO/ASTM standards, visit the ASTM website,
Application. Originally developed as a joint ASTM/ISO standard in conjunction www.astm.org, or contact ASTM Customer Service at [e-mail]. For
with ISO/TC 85/WG 3. Annual Book of ASTM Standards volume information, refer to the standard’s
Current edition approved Dec. 1, 2022. Published May 2024. Originally Document Summary page on the ASTM website.
approved in 1998. Last previous edition approved in 2022 as ISO/ASTM Available from the International Commission on Radiation Units and
51939:2017(2022)(E). DOI: 10.1520/51939-22. Measurements, 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814 U.S.A.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
51939 − 22
2.4 ISO Standards: three-dimensional distribution of absorbed dose, thus rendering
12749-4 Nuclear energy – Vocabulary – Part 4: Dosimetry a map of absorbed-dose values.
for radiation processing 3.1.3.1 Discussion—For a blood canister, such a dose map is
obtained using dosimeters placed at specified locations within
2.5 ISO/IEC Standards:
the canister.
17025 General Requirements for the Competence of Testing
and Calibration Laboratories
3.1.4 activity (A) (of an amount of radionuclide in a
particular energy state at a given time)—quotient of –dN by dt,
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
interval dt (see ICRU 85a).
Force
Recommendations Regarding License Amendments and
A 5 2dN/dt (3)
Procedures for Gamma Irradiation of Blood Products,
−1
6 Unit: s
(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 = 1 s .
Blood Components: A Pilot Program for Licensing (2000)
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
1 Ci = 3.7 × 10 s (exactly).
Reports:
(2) The ‘particular energy state’ is the ground state of the
JCGM 100:2008 GUM 1995, with minor corrections, Evalu-
nuclide unless otherwise specified.
ation of measurement data – Guide to the expression of
(3) The activity of an amount of radionuclide in a particular
uncertainty in measurement
energy state is equal to the product of the decay constant, λ, for
JCGM 200:2012 (JCGM 200:2008 with minor revisions),
that state and the number of nuclei in that state (that is, 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
national metrology institute; or has been formally accredited to
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
D 5 dε¯/dm (1) provided by a laboratory not having formal recognition or
3.1.1.1 Discussion—The SI unit of absorbed dose is the gray accreditation will not necessarily be proof of traceability to a
(Gy), where 1 gray is equivalent to the absorption of 1 joule per
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—
˙
D 5 dD/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
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.
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.
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
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.
51939 − 22
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
3.1.14 measurement management system—set of interre- radiation emitted when atomic electrons make transitions to
more tightly bound states.
lated or interacting elements necessary to achieve metrological
confirmation and continual control of measurement processes.
3.1.25.1 Discussion—In radiation processing applications
(such as blood product irradiation), the principal X-radiation is
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) from an electron beam, consisting of a target,
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, granulocyte concentrates, and fresh or frozen plasma.
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—container used to house the blood product or
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)
51939 − 22
in certain immunocompromised patients and those receiving units containing radionuclides usually have a mechanism to
related-donor products (1, 2). move the canister from the load/unload position to the irradia-
tion position.
4.2 The assurance that blood and blood components have
5.1.1 Some common methods used for improving absorbed-
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
absorbed dose, and may include an upper limit or central target
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
establish operating parameters so as to deliver specified dose to
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
gave values of 1925.20 (60.25) days for Co and 11018.3
blood or blood-equivalent volume for determining the
(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
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 Dosimetry is part of a measurement management system
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
effects on irradiated materials are generally similar, these kinds
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
dose uniformity in the blood canister. Filters are used to reduce
the safety requirements. Currently available units using low-
the low-energy components to improve dose uniformity in the
energy X-radiation (bremsstrahlung) require less shielding than
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.
6.2.5 The absorbed-dose rate and thus time of irradiation is
The boldface numbers in parentheses refer to the bibliography at the end of this
standard. determined by the tube current.
51939 − 22
7. Dosimetry systems tainty achievable with measurements made using a reference
standard dosimetry system is typically of the order of 3 % (at
7.1 Description of Dosimeters and Dosimetry Systems—
the 95 % confidence level).
Classification of dosimeters and dosimetry systems is based on
(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—Classification of dosim-
dosimetry system is based on its application, that is, routine
eters is based on their inherent metrological properties. The
absorbed-dose measurements, including dose mapping and
method of measurement may be important in the classification,
process monitoring.
but the classification does not include consideration of the
(2) The dosimeter used in a routine dosimetry system is
actual instrumentation used, or the quality of preparation
generally a type II dosimeter, although there may be
(manufacturer) of the dosimeter.
exceptions, for example the use of type I alanine dosimeters.
7.1.1.1 Type I Dosimeters—In order for a dosimeter to be
The expanded uncertainty achievable with measurements made
classified as a type I dosimeter, it must be possible to apply
using a routine dosimetry system is typically of the order of
accurate, independent corrections to its response to account for
6 % (at the 95 % confidence level).
the effects of influence quantities, such as temperature and dose
(3) Examples of routine dosimetry systems are listed in
rate. See ISO/ASTM Practice 52628 for a list of type I
Table 2 and described in more detail in Annex A1.
dosimeters.
7.1.1.2 Type II Dosimeters—The classification of a dosim-
7.2 Routine Dosimetry System Calibration:
eter as a type II dosimeter is based on the complexity of
7.2.1 Dosimetry systems consist of dosimeters, measure-
interaction between influence quantities, such as temperature
ment instruments and their associated reference standards, and
and dose rate, which makes it impractical to apply independent
procedures for the system’s use. Prior to use, routine dosimetry
correction factors to the dosimeter response. See ISO/ASTM
systems shall be calibrated in accordance with documented
Practice 52628 for a list of type II dosimeters.
procedures that specify details of the calibration process. The
7.1.2 Classification of Dosimetry Systems:
calibration curve shall cover the dose range of 15 to 50 Gy,
7.1.2.1 Reference Standard Dosimetry Systems:
suitable for blood irradiation. All dosimetry equipment requires
(1) The classification of a dosimetry system as a reference
either calibration traceable to appropriate standards or perfor-
standard dosimetry system is based on its application. Refer-
mance checks to verify its operation (for more information, see
ence standard dosimetry systems are used as standards to
the specific ISO/ASTM standard for the dosimetry system
calibrate other dosimetry systems that are used for routine
being used). Similarly, the dosimetry system shall be calibrated
measurements. In addition, the reference standard dosimetry
for each dosimeter batch used on the blood irradiator. If
systems are used to certify the absorbed-dose rate at a reference
position within the irradiator. The uncertainty of the reference required by regulation or policy, it is necessary to demonstrate
standard dosimetry system will affect the uncertainty of the
that dose measurements are traceable to recognized national or
system being calibrated and thus the uncertainty in the ab-
international standards.
sorbed dose value for the product being irradiated.
7.2.2 Irradiation of calibration dosimeters is a critical com-
(2) Reference standard dosimetry systems may take the
ponent of the calibration of the dosimetry system. These shall
form of systems held at a given location or they may take the
be irradiated at the reference position in the canister where the
form of transfer standard dosimetry systems operated by a
dose rate was determined using reference or transfer standard
national standards laboratory or an approved laboratory. In the
dosimeters issued and analyzed by an approved laboratory. For
case of transfer standard dosimetry systems, dosimeters are
gamma irradiators, the most commonly used transfer standard
sent to a blood irradiation facility for irradiation and then
dosimetry systems for this purpose are either Fricke or alanine-
returned to the issuing laboratory for measurement. The
EPR. For low-energy X-ray irradiators, ionization chambers or
requirement that dosimeters be transported without unduly
the alanine-EPR dosimetry system may be used as transfer
increasing the measurement uncertainty restricts the type of
standard dosimetry systems as long as they are calibrated for
dosimeter that can be used. Alanine/EPR and Fricke dosimetry
the appropriate energy (5, 8, 9).
systems are commonly used in this way.
(3) The dosimeter used in a reference standard dosimetry 7.2.3 Alternately, the dosimeters may be calibrated in ac-
system is generally a type I dosimeter. The expanded uncer- cordance with ISO/ASTM Practice 51261.
TABLE 1 Examples of reference-standard dosimetry systems
Useful Absorbed-dose
Dosimeter Readout System Reference
Range (Gy)
Alanine EPR spectrometer 1 to 10 ISO/ASTM 51607
Fricke UV spectrophotometer 20 to 400 ISO/ASTM 51026
Ionization chamber Electrometer Can be easily applied to the blood-irradiation (5)
dose range
51939 − 22
TABLE 2 Examples of routine dosimetry systems
Useful Absorbed-dose
Dosimeter Readout System Reference
Range (Gy)
–4 3
TLD (for example, LiF) Thermoluminescence reader 10 to 10 ISO/ASTM 51956
MOSFET semiconductor Electronic reader 1 to 200 (6, 7)
RadioChromic film UV/visible spectrophotometer, Transmission/Reflectance 10 to 10 ISO/ASTM 51275
densitometer
Alanine EPR Spectrometer 1 to 10 ISO/ASTM 51607
Radiochromic optical waveguide Photometric means using dual wavelength photometry 1 to 10 ISO/ASTM 51310
Ionization chamber Electrometer Can be easily applied to (5)
the blood-irradiation
dose range
7.2.4 Calibration of the routine dosimetry system shall be tation shall be retained for the life of the irradiator. At a
repeated at regular intervals to ensure that the accuracy of the minimum, it shall include:
absorbed-dose measurement is maintained within required 8.2.1 A description of the irradiator’s specifications, char-
limits. acteristics and parameters, including any modifications made
during or after installation,
7.3 Dosimetry Applications—There are several applications
8.2.2 A description of the location of the irradiator within
of dosimetry systems where blood is irradiated. These may
the operator’s premises, including its relation to any means
include:
provided for segregating unirradiated from irradiated products,
7.3.1 reference or transfer standard dosimetry system is
8.2.3 Operating instructions and standard operating proce-
used to determine the reference absorbed-dose rate in the
dures for the irradiator and associated measurement
canister (see 9.3.1 for more details).
instruments,
7.3.2 routine dosimetry system is used for establishing
8.2.4 Description of the construction and operation of the
absorbed-dose distribution (mapping) in the canister (see 9.3.2
product handling system,
for more details), and
8.2.5 Licensing and safety documents and procedures, in-
7.3.3 routine dosimetry system is used to monitor the
cluding those required by regulatory and occupational health
routine radiation process (see 10.3.3 and 11.2 for more details).
and safety agencies,
7.4 Factors That Affect the Response of Dosimeters:
8.2.6 A description of a calibration program to ensure that
7.4.1 Factors that affect the response of dosimeters (gener-
all processing equipment that may influence absorbed-dose
ally referred to as “influence quantities”), including environ-
delivery is calibrated periodically (for example, the reset timer
mental conditions and variations of such conditions within the
mechanism on a gamma irradiator), and
irradiator, shall be known and their effect taken into account
8.2.7 Descriptions, operating procedures, and calibration
(see ISO/ASTM Practices 52628 and 52701 and the Standard
procedures for associated measurement instruments or systems
of the specific dosimetry system).
(such as those used for dosimetry).
7.4.2 The possible photon energy range for blood irradiation
8.3 Equipment Testi
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: ISO/ASTM 51939 − 2017 (Reapproved 2022)(E) 51939 − 22
Standard Practice for
Blood Irradiation Dosimetry
This standard is issued under the fixed designation ISO/ASTM 51939; the number immediately following the designation indicates the
year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last
reapproval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This practice outlines the irradiator installation qualification program and the dosimetric procedures to be followed during
operational qualification and performance qualification of the irradiator. Procedures for the routine radiation processing 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)
137 60
utilizing radionuclides such as Cs and Co, 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 This document 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 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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.7 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced documents
2.1 ASTM Standards:
E170 Terminology Relating to Radiation Measurements and Dosimetry
This practice is under the jurisdiction of ASTM Committee E61 on Radiation Processing and is the direct responsibility of Subcommittee E61.04 on Specialty Application,
and is also under the jurisdiction of . Originally developed as a joint ASTM/ISO standard in conjunction with ISO/TC 85/WG 3.
Current edition approved Dec. 1, 2022June 1, 2022. . Published May 2024September 2022. Originally published as ASTM E 1939–98. Last previous ASTM edition E
1939–98. The present International Standard ISO/ASTM 51939:2017(2022)(E) is a reapproval of the last previous edition ISO/ASTM 51939:2017(E). Originally approved
in 1998. Last previous edition approved in 2022 as ISO/ASTM 51939:2017(2022)(E). DOI: 10.1520/51939-22.
For referenced ASTM and ISO/ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book
of ASTM Standards volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
51939 − 22
2.2 ISO/ASTM Standards:
51026 Practice for Using the Fricke Dosimetry System
51261 Practice for Calibration of Routine Dosimetry Systems for Radiation Processing
51275 Practice for Use of a Radiochromic Film Dosimetry System
51310 Practice for Use of a Radiochromic Optical Waveguide Dosimetry System
51539 Guide for the Use of Radiation-Sensitive Indicators
51607 Practice for Use of the Alanine-EPR Dosimetry System
51707 Guide for Estimating Uncertainties in Dosimetry for Radiation Processing
51956 Practice for Use of Thermoluminescence-Dosimetry Systems (TLD Systems) for Radiation Processing
52116 Practice for Dosimetry for a Self-Contained Dry-Storage Gamma-Ray Irradiator
52628 Practice for Dosimetry in Radiation Processing
52701 Guide for Performance Characterization of Dosimeters and Dosimetry Systems for Use in Radiation Processing
2.3 International Commission on Radiation Units and Measurements Reports (ICRU):
ICRU 80 Dosimetry Systems for Use in Radiation Processing
ICRU 85a Fundamental Quantities and Units for Ionizing Radiation
2.4 ISO Standards:
12749-4 Nuclear energy – Vocabulary – Part 4: Dosimetry for radiation processing
2.5 ISO/IEC Standards:
17025 General Requirements for the Competence of Testing and Calibration Laboratories
2.6 Guidelines on Blood Irradiation:
Guidelines on the Use of Irradiated Blood Components (2013), Prepared by the BCSH Blood Transfusion Task Force
Recommendations Regarding License Amendments and Procedures for Gamma Irradiation of Blood Products, (1993) US Food
and Drug Administration
Guidance for Industry, Gamma Irradiation of Blood and Blood Components: A Pilot Program for Licensing (2000) US Food and
Drug Administration
2.7 Joint Committee for Guides in Metrology (JCGM) Reports:
JCGM 100:2008 GUM 1995, with minor corrections, Evaluation of measurement data – Guide to the expression of uncertainty
in measurement
JCGM 200:2012 (JCGM 200:2008 with minor revisions), VIM, International vocabulary of metrology – Basis and general
concepts and associated terms
3. Terminology
3.1 Definitions:
3.1.1 absorbed dose (D)—quotient of dɛ¯ by dm, where dɛ¯ is the mean energy imparted by ionizing radiation to matter of mass
dm (see ICRU 85a).
D 5 d¯ε/dm (1)
3.1.1.1 Discussion—
The SI unit of absorbed dose is the gray (Gy), where 1 gray is equivalent to the absorption of 1 joule per kilogram of the specified
material (1 Gy = 1 J/kg).
3.1.2 absorbed-dose rate (D˙)—quotient of dD by dt, where dD is the increment of absorbed dose in the time interval dt, thus
˙
D 5 dD/dt (2)
3.1.2.1 Discussion—
–1
The SI unit is Gy·s . However, the absorbed-dose rate is often specified in terms of its average value over longer time intervals,
–1 –1
for example, in units of Gy·min or Gy·h .
Available from the International Commission on Radiation Units and Measurements, 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814 U.S.A.
Available from International Organization for Standardization (ISO), ISO Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva,
Switzerland, http://www.iso.org.
Available from the National Blood Transfusion Service, East Anglian Blood Transfusion Centre, Long Road, Cambridge, CB2 2PT United Kingdom.
Available from the Office of Communication, Training and Manufacturers Assistance (HFM-40), 1401 Rockville Pike, Rockville, MD 20852-1488, USA.
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://www.bipm.org).
Document produced by working Group 2 of the Joint Committee for Guides in Metrology (JCGM WG2). Available free of charge at the BIPM website
(http://www.bipm.org).
51939 − 22
3.1.3 absorbed-dose mapping—measurement of absorbed dose within an irradiated product to produce a one, two, or
three-dimensional distribution of absorbed dose, thus rendering a map of absorbed-dose values.
3.1.3.1 Discussion—
For a blood canister, such a dose map is obtained using dosimeters placed at specified locations within the canister.
3.1.4 activity (A) (of an amount of radionuclide in a particular energy state at a given time)—quotient of –dN by dt, where dN
is the mean change in the number of nuclei in that energy state due to spontaneous nuclear transitions in the time interval dt (see
ICRU 85a).
A 52dN/dt (3)
−1
Unit: s
−1
The special name for the unit of activity is the becquerel (Bq). 1 Bq = 1 s .
3.1.4.1 Discussion—
10 −1
(1) The former special unit of activity was the curie (Ci). 1 Ci = 3.7 × 10 s (exactly).
(2) The ‘particular energy state’ is the ground state of the nuclide unless otherwise specified.
(3) The activity of an amount of radionuclide in a particular energy state is equal to the product of the decay constant, λ, for
that state and the number of nuclei in that state (that is, A=Nλ).
3.1.5 approved laboratory—laboratory that is a recognized national metrology institute; or has been formally accredited to
ISO/IEC 17025; or has a quality system consistent with the requirements of ISO/IEC 17025.
3.1.5.1 Discussion—
A recognized national metrology institute or other calibration laboratory accredited to ISO/IEC 17025 should be used in order to
ensure traceability to a national or international standard. A calibration certificate provided by a laboratory not having formal
recognition or accreditation will not necessarily be proof of traceability to a national or international standard.
3.1.6 bremsstrahlung—broad-spectrum electromagnetic radiation emitted when an energetic charged particle is influenced by a
strong electric or magnetic field, such as that in the vicinity of an atomic nucleus.
3.1.6.1 Discussion—
(1) In radiation processing, bremsstrahlung photons with sufficient energy to cause ionization are generated by the deceleration
or deflection of energetic electrons in a target material. When an electron passes close to an atomic nucleus, the strong coulomb
field causes the electron to deviate from its original motion. This interaction results in a loss of kinetic 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 kinetic energy of the incident electron.
(2) The bremsstrahlung spectrum depends on the electron energy, the composition and thickness of the target, and the angle
of emission with respect to the incident electron.
3.1.7 calibration—set of operations that establish under specified conditions, the relationship between values of quantities
indicated by a measuring instrument or measuring system, or values represented by a material measure or a reference material, and
the corresponding values realized by standards.
3.1.7.1 Discussion—
Calibration conditions include environmental and irradiation conditions present during irradiation, storage and measurement of the
dosimeters that are used for the generation of a calibration curve.
3.1.8 dosimeter—device that, when irradiated, exhibits a quantifiable change that can be related to absorbed dose in a given
material using appropriate measurement instruments and procedures.
3.1.9 dosimeter batch—quantity of dosimeters made from a specific mass of material with uniform composition, fabricated in a
single production run under controlled, consistent conditions and having a unique identification code.
3.1.10 dosimetry system—system used for measuring absorbed dose, consisting of dosimeters, measurement instruments and their
associated reference standards, and procedures for the system’s use.
3.1.11 installation qualification (IQ)—process of obtaining and documenting evidence that equipment has been provided and
installed in accordance with specifications.
51939 − 22
3.1.12 irradiator turntable—device used to rotate the sample during the irradiation process so as to improve dose uniformity.
3.1.12.1 Discussion—
An irradiator turntable is often referred to as a turntable. Some irradiator geometries, for example with a circular array of radiation
sources surrounding the product, may not need a turntable.
3.1.13 isodose curves—lines or surfaces of constant absorbed dose through a specified medium.
3.1.14 measurement management system—set of interrelated or interacting elements necessary to achieve metrological
confirmation and continual control of measurement processes.
3.1.15 operational qualification (OQ)—process of obtaining and documenting evidence that installed equipment operates within
predetermined limits when used in accordance with its operational procedures.
3.1.16 performance qualification (PQ)—process of obtaining and documenting evidence that the equipment as installed and
operated in accordance with operational procedures, consistently performs in accordance with predetermined criteria and thereby
yields product that meeting its specification.
3.1.17 radiation-sensitive indicator—material such as a coated or impregnated adhesive-backed substrate, ink, coating or other
material which may be affixed to or printed on the product and which undergoes a visual change when exposed to ionizing
radiation.
3.1.17.1 Discussion—
Radiation-sensitive indicators are often referred to as “indicators.”
3.1.18 reference-standard dosimetry system—dosimetry system, generally having the highest metrological quality available at a
given location or in a given organization, from which measurements made there are derived.
3.1.19 routine dosimetry system—dosimetry system calibrated against a reference standard dosimetry system and used for routine
absorbed-dose measurements, including dose mapping and process monitoring.
3.1.20 simulated product—material with radiation absorption and scattering properties similar to those of the product, material or
substance to be irradiated.
3.1.20.1 Discussion—
(1) Simulated product is used during irradiator characterization as a substitute for the actual product, material or substance to
be irradiated.
(2) When used in routine production runs in order to compensate for the absence of product, simulated product is sometimes
referred to as compensating dummy.
(3) When used for absorbed-dose mapping, simulated product is sometimes referred to as phantom material.
3.1.21 timer setting—defined time interval during which product is exposed to radiation.
3.1.22 transfer-standard dosimetry system—dosimetry system used as an intermediary to calibrate other dosimetry systems.
3.1.23 transit dose—absorbed dose delivered to a product (or a dosimeter) while it travels between the non-irradiation position
and the irradiation position, or in the case of a movable source while the source moves into and out of its irradiation position.
3.1.24 validation—documented procedure for obtaining, recording and interpreting the results to establish that a process will
consistently yield product complying with predetermined specifications.
3.1.25 X-radiation—ionizing electromagnetic radiation which includes both bremsstrahlung and the characteristic radiation
emitted when atomic electrons make transitions to more tightly bound states.
3.1.25.1 Discussion—
In radiation processing applications (such as blood product irradiation), the principal X-radiation is bremmstrahlung.
51939 − 22
3.1.26 X-ray converter—device for generating X-radiation (bremsstrahlung) from an electron beam, consisting of a target, means
for cooling the target, and a supporting structure.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 blood product (blood and blood components)—whole blood, red cells, frozen cells, platelet concentrates, apheresis platelets,
granulocyte concentrates, and fresh or frozen plasma.
3.2.1.1 Discussion—
Enclosure systems for blood and blood components are commonly referred to as “bags.”
3.2.2 canister—container used to house the blood product or blood-equivalent product during the irradiation process.
3.3 Definitions of other terms used in this standard that pertain to radiation measurement and dosimetry may be found in ISO
12749-4, ASTM Terminology E170, ICRU 85a and VIM; these documents, therefore, may be used as alternative references.
4. Significance and use
4.1 Blood and blood components are irradiated to predetermined absorbed doses to inactivate viable lymphocytes to help prevent
transfusion-induced graft-versus-host disease (GVHD) in certain immunocompromised patients and those receiving related-donor
products (1, 2).
4.2 The assurance that blood and blood components have been properly irradiated is of crucial importance for patient health. This
shall be demonstrated by means of accurate absorbed-dose measurements on the product, or in simulated product.
137 60
4.3 Blood and blood components are usually irradiated using gamma radiation from Cs or Co sources, or X-radiation from
X-ray units.
4.4 Blood irradiation specifications include a lower limit of absorbed dose, and may include an upper limit or central target dose.
For a given application, any of these values may be prescribed by regulations that have been established on the basis of available
scientific data (see 2.6).
4.5 For each blood irradiator, an absorbed-dose rate at a reference position within the canister is measured as part of irradiator
acceptance testing using a reference-standard dosimetry system. That reference-standard measurement is used to establish
operating parameters so as to deliver specified dose to blood and blood components.
4.6 Absorbed-dose measurements are performed within the blood or blood-equivalent volume for determining the absorbed-dose
distribution. Such measurements are often performed using simulated product (for example, polystyrene is considered blood
equivalent for Cs photon energies).
4.7 Dosimetry is part of a measurement management system that is applied to ensure that the radiation process meets
predetermined specifications (see ISO/ASTM Practice 52628).
4.8 Blood and blood components are usually irradiated in chilled or frozen condition. Care should be taken, therefore, to ensure
that the dosimeters and radiation-sensitive indicators can be used under such temperature conditions.
4.9 Proper documentation and record keeping are critical components of a radiation process. Documentation and record keeping
requirements may be specified by regulatory authorities or may be given in the corporation’s quality policy.
4.10 Response of most dosimeters has significant energy dependence at photon energies of less than 100 keV, so proper care must
be exercised when measuring absorbed dose in that energy range.
The boldface numbers in parentheses refer to the bibliography at the end of this standard.
51939 − 22
5. Type of irradiators and modes of operation
137 60
5.1 Self-contained irradiators expose samples to gamma irradiation produced by isotopes of either Cs or Co (3) (ISO/ASTM
Practice 52116), or to low energy X-radiation (bremsstrahlung) produced by an X-ray tube. These irradiators house their radiation
source in a protective lead shield or other appropriate high atomic number material in accordance with the safety requirements.
Currently available units using low-energy X-radiation (bremsstrahlung) require less shielding than units containing gamma-
emitting radioactive isotopes. Such units containing radionuclides usually have a mechanism to move the canister from the
load/unload position to the irradiation position.
5.1.1 Some common methods used for improving absorbed-dose uniformity in the blood product are to either rotate the canister
holding the blood product in front of the radiation source or to have multiple sources irradiating the product from different
directions.
6. Radiation source characteristics
6.1 Gamma Irradiators:
60 137
6.1.1 The source of gamma radiation used in the irradiators considered in this practice consists of sealed Co or Cs
radionuclides that are typically linear rods arranged in one or more planar or annular arrays.
6.1.2 Cobalt-60 emits photons with energies of approximately 1.17 and 1.33 MeV in nearly equal proportions. Cesium-137
produces photons with energies of approximately 0.662 MeV.
60 137
6.1.3 The radioactive decay half-lives for Co and Cs are regularly reviewed and updated. The most recent publication by the
60 137
National Institute of Standards and Technology gave values of 1925.20 (60.25) days for Co and 11018.3 (69.5) days for Cs
(4).
6.1.4 For gamma sources, the only variation in the source output is the known reduction in the activity caused by radioactive
decay. This reduction in the source output and the required increase in the irradiation time to deliver the same dose may be
calculated (see 10.4.2) or obtained from tables provided by the irradiator manufacturer.
6.2 X-ray Irradiators:
6.2.1 Low energy X-ray irradiators use X-ray tubes that consist of an electron source (generally a heated wire, a filament which
emits electrons), an electrostatic field to accelerate these electrons, and a converter to generate X-radiation.
6.2.2 An X-ray (bremsstrahlung) irradiator emits short-wavelength electromagnetic radiation, which is analogous to gamma
radiation from radioactive sources. Although their effects on irradiated materials are generally similar, these kinds of radiation
differ in their energy spectra (see 6.2.3), angular distribution, and dose rates. The physical characteristics of the X-radiation
(bremsstrahlung) field depend on the design of the X-ray tube.
6.2.3 Currently available low-energy X-ray irradiators generate X-radiation with a maximum energy of 160 keV. The spectrum
of the X-ray energy extends from the maximum energy to approximately 30 keV.
6.2.4 The energy of the X-radiation influences the size and shape of the canister needed to achieve the desired level of dose
uniformity in the blood canister. Filters are used to reduce the low-energy components to improve dose uniformity in the canister.
These filters may form part of the X-ray tube or may be material added to the irradiator or canister. Reflectors may also be used
to improve the dose uniformity.
6.2.5 The absorbed-dose rate and thus time of irradiation is determined by the tube current.
7. Dosimetry systems
7.1 Description of Dosimeters and Dosimetry Systems—Classification of dosimeters and dosimetry systems is based on the
inherent metrological dosimeter properties and the field of application of the dosimetry system (see ISO/ASTM Practice 52628).
These classifications influence both the selection and calibration of dosimetry systems.
7.1.1 Classification of Dosimeters—Classification of dosimeters is based on their inherent metrological properties. The method of
51939 − 22
measurement may be important in the classification, but the classification does not include consideration of the actual
instrumentation used, or the quality of preparation (manufacturer) of the dosimeter.
7.1.1.1 Type I Dosimeters—In order for a dosimeter to be classified as a type I dosimeter, it must be possible to apply accurate,
independent corrections to its response to account for the effects of influence quantities, such as temperature and dose rate. See
ISO/ASTM Practice 52628 for a list of type I dosimeters.
7.1.1.2 Type II Dosimeters—The classification of a dosimeter as a type II dosimeter is based on the complexity of interaction
between influence quantities, such as temperature and dose rate, which makes it impractical to apply independent correction factors
to the dosimeter response. See ISO/ASTM Practice 52628 for a list of type II dosimeters.
7.1.2 Classification of Dosimetry Systems:
7.1.2.1 Reference Standard Dosimetry Systems:
(1) The classification of a dosimetry system as a reference standard dosimetry system is based on its application. Reference
standard dosimetry systems are used as standards to calibrate other dosimetry systems that are used for routine measurements. In
addition, the reference standard dosimetry systems are used to certify the absorbed-dose rate at a reference position within the
irradiator. The uncertainty of the reference standard dosimetry system will affect the uncertainty of the system being calibrated and
thus the uncertainty in the absorbed dose value for the product being irradiated.
(2) Reference standard dosimetry systems may take the form of systems held at a given location or they may take the form
of transfer standard dosimetry systems operated by a national standards laboratory or an approved laboratory. In the case of transfer
standard dosimetry systems, dosimeters are sent to a blood irradiation facility for irradiation and then returned to the issuing
laboratory for measurement. The requirement that dosimeters be transported without unduly increasing the measurement
uncertainty restricts the type of dosimeter that can be used. Alanine/EPR and Fricke dosimetry systems are commonly used in this
way.
(3) The dosimeter used in a reference standard dosimetry system is generally a type I dosimeter. The expanded uncertainty
achievable with measurements made using a reference standard dosimetry system is typically of the order of 3 % (at the 95 %
confidence level).
(4) Examples of reference standard dosimetry systems are given in Table 1.
7.1.2.2 Routine Dosimetry Systems:
(1) The classification of a dosimetry system as a routine dosimetry system is based on its application, that is, routine
absorbed-dose measurements, including dose mapping and process monitoring.
(2) The dosimeter used in a routine dosimetry system is generally a type II dosimeter, although there may be exceptions, for
example the use of type I alanine dosimeters. The expanded uncertainty achievable with measurements made using a routine
dosimetry system is typically of the order of 6 % (at the 95 % confidence level).
(3) Examples of routine dosimetry systems are listed in Table 2 and described in more detail in Annex A1.
7.2 Routine Dosimetry System Calibration:
7.2.1 Dosimetry systems consist of dosimeters, measurement instruments and their associated reference standards, and procedures
for the system’s use. Prior to use, routine dosimetry systems shall be calibrated in accordance with documented procedures that
specify details of the calibration process. The calibration curve shall cover the dose range of 15 to 50 Gy, suitable for blood
irradiation. All dosimetry equipment requires either calibration traceable to appropriate standards or performance checks to verify
its operation (for more information, see the specific ISO/ASTM standard for the dosimetry system being used). Similarly, the
dosimetry system shall be calibrated for each dosimeter batch used on the blood irradiator. If required by regulation or policy, it
is necessary to demonstrate that dose measurements are traceable to recognized national or international standards.
7.2.2 Irradiation of calibration dosimeters is a critical component of the calibration of the dosimetry system. These shall be
irradiated at the reference position in the canister where the dose rate was determined using reference or transfer standard
TABLE 1 Examples of reference-standard dosimetry systems
Useful Absorbed-dose
Dosimeter Readout System Reference
Range (Gy)
Alanine EPR spectrometer 1 to 10 ISO/ASTM 51607
Fricke UV spectrophotometer 20 to 400 ISO/ASTM 51026
Ionization chamber Electrometer Can be easily applied to the blood-irradiation (5)
dose range
51939 − 22
TABLE 2 Examples of routine dosimetry systems
Useful Absorbed-dose
Dosimeter Readout System Reference
Range (Gy)
–4 3
TLD (for example, LiF) Thermoluminescence reader 10 to 10 ISO/ASTM 51956
MOSFET semiconductor Electronic reader 1 to 200 (6, 7)
RadioChromic film UV/visible spectrophotometer, Transmission/Reflectance 10 to 10 ISO/ASTM 51275
densitometer
Alanine EPR Spectrometer 1 to 10 ISO/ASTM 51607
Radiochromic optical waveguide Photometric means using dual wavelength photometry 1 to 10 ISO/ASTM 51310
Ionization chamber Electrometer Can be easily applied to (5)
the blood-irradiation
dose range
dosimeters issued and analyzed by an approved laboratory. For gamma irradiators, the most commonly used transfer standard
dosimetry systems for this purpose are either Fricke or alanine-EPR. For low-energy X-ray irradiators, ionization chambers or the
alanine-EPR dosimetry system may be used as transfer standard dosimetry systems as long as they are calibrated for the
appropriate energy (5, 8, 9).
7.2.3 Alternately, the dosimeters may be calibrated in accordance with ISO/ASTM Practice 51261.
7.2.4 Calibration of the routine dosimetry system shall be repeated at regular intervals to ensure that the accuracy of the
absorbed-dose measurement is maintained within required limits.
7.3 Dosimetry Applications—There are several applications of dosimetry systems where blood is irradiated. These may include:
7.3.1 reference or transfer standard dosimetry system is used to determine the reference absorbed-dose rate in the canister (see
9.3.1 for more details).
7.3.2 routine dosimetry system is used for establishing absorbed-dose distribution (mapping) in the canister (see 9.3.2 for more
details), and
7.3.3 routine dosimetry system is used to monitor the routine radiation process (see 10.3.3 and 11.2 for more details).
7.4 Factors That Affect the Response of Dosimeters:
7.4.1 Factors that affect the response of dosimeters (generally referred to as “influence quantities”), including environmental
conditions and variations of such conditions within the irradiator, shall be known and their effect taken into account (see
ISO/ASTM Practices 52628 and 52701 and the Standard of the specific dosimetry system).
7.4.2 The possible photon energy range for blood irradiation applications is from 40 keV to 1.33 MeV. Since response of many
routine dosimeters depends on the photon energy, care must be taken to calibrate the dosimetry system for appropriate energy
ranges.
8. Installation qualification
8.1 Objective—The purpose of an installation qualification program is to obtain and document evidence that the irradiator and
measurement instruments have been delivered and installed in accordance with their specifications. Installation qualification
includes documentation of the irradiator equipment and measurement instruments; establishment of testing, operation and
calibration procedures for their use; and verification that the installed irradiator equipment and measurement instruments operate
according to specification.
NOTE 1—Table A2.1 gives some recommended steps in the following areas: installation qualification, operational qualification, performance qualification,
and routine product processing. The recommended steps in Table A2.1 are not meant to be exhau
...