SIST EN ISO 19238:2023
(Main)Radiological protection - Performance criteria for service laboratories performing biological dosimetry by cytogenetics - Dicentric assay (ISO 19238:2023)
Radiological protection - Performance criteria for service laboratories performing biological dosimetry by cytogenetics - Dicentric assay (ISO 19238:2023)
This document provides criteria for quality assurance and quality control, evaluation of the performance and the accreditation of biological dosimetry by cytogenetic service laboratories using the dicentric assay performed with manual scoring.
This document is applicable to
a) the confidentiality of personal information, for the requestor and the service laboratory,
b) the laboratory safety requirements,
c) the calibration sources and calibration dose ranges useful for establishing the reference dose-response curves that contribute to the dose estimation from unstable chromosome aberration frequency and the detection limit,
d) the scoring procedure for unstable chromosome aberrations used for biological dosimetry,
e) the criteria for converting a measured aberration frequency into an estimate of absorbed dose,
f) the reporting of results,
g) the quality assurance and quality control, and
h) informative annexes containing sample instructions for requestor (see Annex A), sample questionnaire (see Annex B), sample report (see Annex C), fitting of the low dose-response curve by the method of maximum likelihood and calculating the error of the dose estimate (see Annex D), odds ratio method for cases of suspected exposure to a low dose (see Annex E), a method for determining the decision threshold and detection limit (see Annex F) and sample data sheet for recording aberrations (see Annex G).
Strahlenschutz - Durchführungskriterien für Dienstleistungslaboratorien zur Anwendung der biologischen Dosimetrie mittels zytogenetischer Verfahren - Dizentrische Chromosomenanalyse (ISO 19238:2023)
Dieses Dokument stellt Kriterien für die Qualitätssicherung und Qualitätskontrolle, Validierung der Durchführung und Akkreditierung der biologischen Dosimetrie durch zytogenetische Dienstleistungslaboratorien, die die dizentrische Chromosomenanalyse mit manueller Auswertung verwenden, bereit.
Dieses Dokument ist anwendbar auf:
a) die Vertraulichkeit von persönlichen Angaben, in Bezug auf den Auftraggeber und das Dienstleistungslaboratorium;
b) die Laboratorium-Sicherheitsanforderungen;
c) die Kalibrierquellen (Kalibrierstrahler) und Kalibrierdosisbereiche, die zur Erstellung der Referenz-Dosis-Wirkungs-Kurven nützlich sind, die zur Dosisabschätzung anhand der Häufigkeit von instabilen Chromosomenaberrationen und der Nachweisgrenze beitragen;
d) das Auswerteverfahren für instabile Chromosomenaberrationen, die für die biologische Dosimetrie verwendet werden;
e) die Kriterien für die Abschätzung der absorbierten Dosis, anhand der Häufigkeit von beobachteten Aberrationen;
f) die Berichterstattung der Ergebnisse;
g) die Qualitätssicherung und Qualitätskontrolle, und
h) informative Anhänge mit Musteranweisungen für Auftraggeber (siehe Anhang A), Musterfragebogen (siehe Anhang B), Musterbericht (siehe Anhang C), Anpassung der Niedrigdosis-Wirkungs-Kurve nach dem Maximum-Likelihood-Methode und Berechnung des Fehlers der Dosisschätzung (siehe Anhang D), Odds Ratio-Verfahren für Fälle einer vermuteten Exposition mit geringer Dosis (siehe Anhang E), sowie ein Verfahren zur Bestimmung der Erkennungsgrenze und Nachweisgrenze (siehe Anhang F) und ein Musterdatenblatt für die Erfassung der Aberrationen (siehe Anhang G).
Radioprotection - Critères de performance pour les laboratoires de service pratiquant la dosimétrie biologique par cytogénétique - Dénombrement des dicentriques (ISO 19238:2023)
Le présent document fournit des critères pour l’assurance qualité et le contrôle qualité, l’évaluation des performances et l’accréditation des laboratoires de service pratiquant la dosimétrie biologique par cytogénétique via un dénombrement manuel des dicentriques.
Le présent document s'applique à
a) la confidentialité des informations personnelles pour le demandeur et le laboratoire de service,
b) les exigences de sécurité du laboratoire,
c) les sources d’étalonnage et les gammes de doses d’étalonnage utiles pour établir les courbes dose-réponse de référence qui contribuent à l’estimation de dose à partir de la fréquence des aberrations chromosomiques instables, et la limite de détection,
d) la procédure de dénombrement des aberrations chromosomiques instables utilisées pour la dosimétrie biologique,
e) les critères pour convertir une fréquence mesurée d’aberrations en une estimation de dose absorbée,
f) la présentation des résultats,
g) l’assurance qualité et le contrôle qualité, et
h) les annexes informatives contenant des exemples: d’instructions pour le demandeur (voir Annexe A), de questionnaire (voir Annexe B), de rapport (voir Annexe C), d’ajustement de la courbe dose-réponse aux faibles doses par la méthode du maximum de vraisemblance et en tenant compte de l’erreur de l’estimation de dose (voir Annexe D), de méthode de rapport de chances pour les cas d’exposition suspectée à une faible dose(voir Annexe E), de méthode de détermination du seuil de décision et de la limite de détection (voir Annexe F) et de tableau type pour le dénombrement des aberrations chromosomiques (voir Annexe G).
Radiološka zaščita - Merila za delovanje laboratorijev, ki izvajajo biološko dozimetrijo s citogenetiko - Diecentrična analiza (ISO 19238:2023)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-november-2023
Radiološka zaščita - Merila za delovanje laboratorijev, ki izvajajo biološko
dozimetrijo s citogenetiko - Diecentrična analiza (ISO 19238:2023)
Radiological protection - Performance criteria for service laboratories performing
biological dosimetry by cytogenetics - Dicentric assay (ISO 19238:2023)
Strahlenschutz - Durchführungskriterien für Dienstleistungslaboratorien zur Anwendung
der biologischen Dosimetrie mittels zytogenetischer Verfahren - Dizentrische
Chromosomenanalyse (ISO 19238:2023)
Radioprotection - Critères de performance pour les laboratoires de service pratiquant la
dosimétrie biologique par cytogénétique - Dénombrement des dicentriques (ISO
19238:2023)
Ta slovenski standard je istoveten z: EN ISO 19238:2023
ICS:
13.280 Varstvo pred sevanjem Radiation protection
17.240 Merjenje sevanja Radiation measurements
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN ISO 19238
EUROPEAN STANDARD
NORME EUROPÉENNE
September 2023
EUROPÄISCHE NORM
ICS 13.280; 17.240 Supersedes EN ISO 19238:2017
English Version
Radiological protection - Performance criteria for service
laboratories performing biological dosimetry by
cytogenetics - Dicentric assay (ISO 19238:2023)
Radioprotection - Critères de performance pour les Strahlenschutz - Durchführungskriterien für
laboratoires de service pratiquant la dosimétrie Dienstleistungslaboratorien zur Anwendung der
biologique par cytogénétique - Dénombrement des biologischen Dosimetrie mittels zytogenetischer
dicentriques (ISO 19238:2023) Verfahren - Dizentrische Chromosomenanalyse (ISO
19238:2023)
This European Standard was approved by CEN on 12 August 2023.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 19238:2023 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
This document (EN ISO 19238:2023) has been prepared by Technical Committee ISO/TC 85 "Nuclear
energy, nuclear technologies, and radiological protection" in collaboration with Technical Committee
CEN/TC 430 “Nuclear energy, nuclear technologies, and radiological protection” the secretariat of
which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by March 2024, and conflicting national standards shall
be withdrawn at the latest by March 2024.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 19238:2017.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 19238:2023 has been approved by CEN as EN ISO 19238:2023 without any modification.
INTERNATIONAL ISO
STANDARD 19238
Third edition
2023-08
Radiological protection —
Performance criteria for service
laboratories performing biological
dosimetry by cytogenetics — Dicentric
assay
Radioprotection — Critères de performance pour les laboratoires
de service pratiquant la dosimétrie biologique par cytogénétique —
Dénombrement des dicentriques
Reference number
ISO 19238:2023(E)
ISO 19238:2023(E)
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 19238:2023(E)
Contents Page
Foreword .v
Introduction .vii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 3
5 Dicentric assay . 4
6 Responsibility of the requestor . 5
7 Responsibility of the service laboratory . 5
7.1 Setup and sustainment of the QA program . 5
7.2 Responsibility during service . 5
8 Confidentiality of personal information . 6
8.1 Overview . 6
8.2 Applications of the principle of confidentiality . 7
8.2.1 Delegation of responsibilities within the laboratory. 7
8.2.2 Requests for analysis . . 7
8.2.3 Transmission of confidential information . 7
8.2.4 Anonymity of samples . 7
8.2.5 Reporting of results . 7
8.2.6 Storage . 7
8.2.7 Data security plan . 7
9 Laboratory safety requirements . 8
9.1 Overview . 8
9.2 Microbiological safety requirements . 8
9.3 Chemical safety . 8
9.4 Optical safety requirements . 9
10 Sample processing. 9
10.1 Culturing . 9
10.2 Scoring . 10
10.2.1 Coding of samples and slides . 10
10.2.2 Scoring techniques . 10
10.2.3 Procedure for scoring first-division metaphases . 10
10.2.4 Laboratory scoring expertise . 11
11 Calibration curves .11
11.1 Calibration source(s) . 11
11.2 Establishment of calibration curve(s) . 11
12 Criteria for converting a measured aberration frequency into an estimate of
absorbed dose .13
12.1 General .13
12.2 Testing the distribution of aberrations per cell . 13
12.3 Comparison with the background level: Characterisation of the minimum
detectable dose. 14
12.4 Confidence limits on the number of dicentrics . 16
12.5 Calculation of absorbed dose for whole-body exposures . 17
12.6 Calculation of uncertainty on absorbed dose . 17
12.7 Acute and non-acute exposure cases . 18
12.8 Partial body and prior exposure cases . 18
12.9 Other exposure scenarios . 19
13 Reporting of results .20
iii
ISO 19238:2023(E)
13.1 General . 20
13.2 Content of the report (see Annex C for a standard form) . 20
13.3 Interpretation of the results. 20
14 Quality assurance and quality control .21
14.1 Overview . 21
14.2 Specific requirements . 21
14.2.1 General . 21
14.2.2 Performance checks by laboratory inter-comparisons . 21
14.2.3 Periodical performance check of scorer qualification .22
14.2.4 Performance checks of sample transport integrity .22
14.2.5 Performance checks of sample integrity by service laboratory .22
14.2.6 Performance checks for instrumentation . 23
14.2.7 Performance checks of sample protocol . 23
14.2.8 Performance checks of sample scoring . 23
14.2.9 Performance checks of dose and confidence limits estimation .23
14.2.10 Performance checks for result report generation .23
Annex A (informative) Sample instructions for requestor .24
Annex B (informative) Sample questionnaire .26
Annex C (informative) Sample of report .28
Annex D (informative) Fitting of the low-LET dose-response curve by the method of
maximum likelihood and calculating the error of dose estimate .30
Annex E (informative) Odds ratio method for cases of suspected exposure to a low dose .33
Annex F (informative) Decision threshold and detection limit .35
Annex G (informative) Sample data sheet for recording aberrations .38
Bibliography .39
iv
ISO 19238:2023(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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO document should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use
of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed
patent rights in respect thereof. As of the date of publication of this document, ISO had received notice of
(a) patent(s) which may be required to implement this document. However, implementers are cautioned
that this may not represent the latest information, which may be obtained from the patent database
available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent
rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technologies,
and radiological protection, Subcommittee SC 2, Radiological protection, in collaboration with the
European Committee for Standardization (CEN) Technical Committee CEN/TC 430, Nuclear energy,
nuclear technologies, and radiological protection, in accordance with the Agreement on technical
cooperation between ISO and CEN (Vienna Agreement).
This third edition cancels and replaces the second edition (ISO 19238:2014), of which it constitutes a
minor revision.
The main changes are as follows:
— title changed from “Radiological Protection — Performance criteria for service laboratory performing
biological dosimetry by cytogenetics” to “Radiological protection — Performance criteria for service
laboratory performing biological dosimetry by cytogenetics — Dicentric assay”;
— minor edits to text throughout;
— addition of 8.2.7 on data security plan;
— simplification of laboratory safety requirements including deletion of safety plan to demonstrate
that each laboratory shall meet the requirements of their country;
— addition of material related to automated analysis;
— addition of detail in 10.2.3 on scoring first-division metaphases;
— addition of detail in 11.2, Establishment of calibration curve(s);
— addition of details on determining the minimal resolvable dose.
v
ISO 19238:2023(E)
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
vi
ISO 19238:2023(E)
Introduction
The widening use of ionising radiations for medical, industrial, agricultural, research, and military
purposes increases the risk of overexposure of radiation workers and individuals of the general
population. Biological dosimetry, based on the study of chromosomal aberrations, mainly through the
dicentric assay, has become a routine component of accidental dose assessment. Experience with its
application in hundreds of cases of suspected or verified overexposures has proven the value of this
method and also defined its limitations. It should be emphasized that dicentric chromosome analysis is
used as a dosimeter and provides one input into the compendium of information needed for assessment
of a radiological incident.
Many studies on animals and humans have shown that one can establish a good correlation between the
results obtained in vivo and in vitro, so that in vitro established dose-effect relationships from irradiated
blood samples can be used to form calibration curves. The dicentric yield is dependent on radiation
quality and dose rate, as well as the circumstances of exposure, for example time since exposure,
homogeneity, so information about these variables is important for each investigation. If known, these
exposure characteristics are important for refining the aberration dose estimates. The specificity
of this technique is enhanced by the fact that generally 1 dicentric is observed per 1 000 metaphase
spreads in the normal population, and that this frequency is essentially independent of age and sex.
The precision of the technique thus depends on the number of cells observed, the background level, and
the calibration curve used. Theoretically, it is possible to detect exposure as low as 0,01 Gy, however,
for such low doses, it is necessary to analyse tens of thousands of metaphase spreads. In practice, this
level of detection is neither feasible nor necessary. The upper dose detection limits extend well into the
range of doses that are lethal to humans.
The primary purpose of this document is to provide a guideline to all laboratories in order to
perform the dicentric assay using documented and validated procedures. Secondly, it facilitates the
comparison of results obtained in different laboratories, particularly for international collaborations or
interlaboratory comparisons. Finally, laboratories newly commissioned to carry out the dicentric assay
should conform to this document in order to perform the assay reproducibly and accurately.
This document is written in the form of procedures to be adopted for biological dosimetry for
overexposures involving, at most, a few casualties. The criteria required for such measurements usually
depends upon the application of the results: radiation protection management, medical management
when appropriate, record keeping, and legal requirements. In the special situation of a mass radiation
casualty and limited resources, the technique can be applied for emergency triage analysis as described
[1]
in ISO 21243 .
A part of the information in this document can be found in other international guidelines and scientific
publications, primarily in the International Atomic Energy Agency’s (IAEA) Technical Reports series
[2]
on biological dosimetry . However, this document expands and standardizes the quality assurance
and quality control, the criteria of accreditation, and the evaluation of performance. This document
is generally compliant with ISO/IEC 17025, with particular consideration given to the specific needs
of biological dosimetry. The expression of uncertainties in dose estimations given in this document
[3]
comply with the ISO guide to the expression of uncertainty in measurement (ISO/IEC Guide 98-1 ) and
[4] [5] [6]
the ISO 5725-1 , ISO 5725-2 and ISO 5725-3 on accuracy (trueness and precision) of measurement
methods and results.
vii
INTERNATIONAL STANDARD ISO 19238:2023(E)
Radiological protection — Performance criteria for
service laboratories performing biological dosimetry by
cytogenetics — Dicentric assay
1 Scope
This document provides criteria for quality assurance and quality control, evaluation of the performance
and the accreditation of biological dosimetry by cytogenetic service laboratories using the dicentric
assay performed with manual scoring.
This document is applicable to
a) the confidentiality of personal information, for the requestor and the service laboratory,
b) the laboratory safety requirements,
c) the calibration sources and calibration dose ranges useful for establishing the reference dose-
response curves that contribute to the dose estimation from unstable chromosome aberration
frequency and the detection limit,
d) the scoring procedure for unstable chromosome aberrations used for biological dosimetry,
e) the criteria for converting a measured aberration frequency into an estimate of absorbed dose,
f) the reporting of results,
g) the quality assurance and quality control, and
h) informative annexes containing sample instructions for requestor (see Annex A), sample
questionnaire (see Annex B), sample report (see Annex C), fitting of the low dose-response curve
by the method of maximum likelihood and calculating the error of the dose estimate (see Annex D),
odds ratio method for cases of suspected exposure to a low dose (see Annex E), a method for
determining the decision threshold and detection limit (see Annex F) and sample data sheet for
recording aberrations (see Annex G).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
ISO 19238:2023(E)
3.1
acentric
terminal or interstitial chromosome fragment of varying size, referred to as an excess acentric fragment
when it is formed independently of a dicentric or centric ring chromosome aberration
3.2
background frequency
background level
spontaneous frequency (or number) of chromosome aberrations recorded in control samples or
individuals
3.3
centric ring
aberrant circular chromosome resulting from the joining of two breaks on separate arms of the same
chromosome
Note 1 to entry: It is generally accompanied by an acentric (3.1) fragment.
3.4
confidence interval
range within which the true value of a statistical quantity lies with a specified probability
3.5
chromosome
structure that comprises discrete packages of DNA and proteins that carry genetic information, and
which condenses to form characteristically shaped bodies during nuclear division
3.6
chromatid
either of the two strands of a duplicated chromosome (3.5) that are joined by a single centromere and
which separate during cell division to become individual chromosomes (3.5)
3.7
cytogenetics
branch of genetics that deals with the study of chromosomes (3.5)
3.8
dicentric
aberrant chromosome (3.5) having two centromeres derived from the joining of parts from two broken
chromosomes (3.5), generally accompanied by an acentric (3.1) fragment
3.9
interphase
period of a cell cycle between mitotic divisions
3.10
linear energy transfer
LET
quotient of the mean energy lost by the charged particles due to electronic interactions in traversing a
distance in the material, minus the mean sum of the kinetic energies in excess of the maximum energy
of electrons locally deposited, of all the electrons released by the charged particles and the distance
traversed
3.11
metaphase
stage of mitosis when the nuclear membrane is dissolved and the chromosomes (3.5) are condensed to
their minimum lengths and aligned for division
3.12
mitotic index
percentage of cells of a cell population under division at a particular time of observation
ISO 19238:2023(E)
3.13
precision
concept used to describe dispersion of measurements with respect to a measure of location or central
tendency
3.14
quality assurance
QA
planned and systematic actions necessary to provide adequate confidence that a process, measurement,
or service satisfies given requirements for quality
3.15
quality control
QC
planned and systematic actions intended to verify that systems and components conform with
predetermined requirements
3.16
Qdr method
chromosome (3.5) aberration yield in cells with a chromosome (3.5) aberration, typically calculated as
the number of dicentrics and/or rings divided by the number of metaphase (3.11) spreads with either a
dicentric or ring
3.17
service laboratory
laboratory performing biological dosimetry measurements
4 Abbreviated terms
BrdU Bromodeoxyuridine
Co Cobalt
covar Covariance
Cs Cesium
Cu Copper
DNA Deoxyribonucleic acid
FBS Foetal bovine serum
FpG Fluorescence plus Giemsa
GHS Globally Harmonized System of Classification and Labelling of Chemicals
Gy Gray
H Null hypothesis
H Alternative hypothesis
HVL Half-value layer
IAEA International Atomic Energy Agency
IATA International Air Transport Association
IEC International Electrochemical Commission
ISO 19238:2023(E)
ISO International Organization for Standardization
IU International units
KCl Potassium chloride
LET Linear energy transfer
MEM Minimum essential medium
PHA Phytohaemagglutinin
R Coefficient of determination
SE Standard error
SSD Source-to-surface distance
TBT Technical Barriers to Trade
TC Technical Committee
var Variance
WTO World Trade Organization
y Decision threshold
d
y Detection limit
z
5 Dicentric assay
Determining the frequency of unstable chromosomal aberrations at metaphase in cultured human
peripheral blood lymphocytes is the recommended method for biological dosimetry. The chromosome
aberrations to be used are either dicentrics only or dicentrics plus centric rings. For the application of
this document, the service laboratory shall choose which type of aberrations to score for the purpose
of assessing dose estimates and shall be consistent throughout. Hereafter, chromosome aberrations are
referred to as dicentrics but may include centric rings if determined by the service laboratory.
Lymphocytes are cultured by a method that permits first-division metaphases to be recognized for
analysis (see 10.1). This requires either whole blood, or lymphocytes separated from the other blood
components, to be incubated in a culture medium that enables the scoring of first-generation metaphase
cells. A mitotic blocking agent, colcemid or colchicine, is added to arrest dividing lymphocytes
in metaphase. The duration of the cell culture and the timing of addition of the arresting agent are
optimised to ensure an adequate mitotic index and predominance of high quality, first-division
metaphases.
Metaphases are recovered from the cultures by centrifugation, placing in a hypotonic salt solution and
fixing in a mixture of alcohol and acetic acid. Fixed cells are placed on microscope slides and stained.
The exact protocol for cell culture, harvesting metaphases, and staining used by a service laboratory
shall be formally documented (see Clause 10).
Microscope slides containing stained cells are scanned to identify suitable first-division metaphases
to score chromosome aberrations (see 10.2). The frequency of dicentrics observed in an appropriate
number of scored metaphases is converted to an estimate of radiation dose by reference to calibration
data (see Clause 11).
ISO 19238:2023(E)
6 Responsibility of the requestor
This clause includes items that are not controlled by the service laboratory. Prior to blood sampling,
an initial conversation between the requestor and the service laboratory should occur to co-ordinate
the sample collection and shipment. Specific requirements regarding sample collection and shipment
should be explained to the requestor including the approximate delivery time for the assay result(s). A
standard instruction sheet (illustrated in Annex A) explaining the requirements should be sent to the
requestor. The requirements include:
a) Blood sampling should use vacutainers containing lithium or sodium heparin as the anticoagulant
and the vacutainers should either be sent or specified by the service laboratory.
b) Blood should be collected (ideally about 10 ml), labelled accurately and unambiguously, maintained
at room temperature (around 20 °C), and sent to the service laboratory as soon as possible.
c) Precautions should be taken to ensure the integrity of the container to prevent leakage during
shipment. Blood samples should not be frozen during shipment and ideally be kept between 11 °C
[2]
to 30 °C during shipment, although a lower temperature, above freezing, is still acceptable . A
temperature recording device should be included to ensure that the temperature during shipment
is controlled. Packaging and labelling shall conform to national and international regulations. If air
transportation is involved, a physical dosimeter should be included to monitor whether the sample
was irradiated in transit.
d) A questionnaire (see Annex B) provided by the service laboratory should be completed and
returned prior to the start of blood culturing.
e) The laboratory shall be alerted of biologically contaminated and/or infectious samples so that
extra precautions may be taken when handling the sample.
7 Responsibility of the service laboratory
7.1 Setup and sustainment of the QA program
The service laboratory shall establish and maintain a QA program (see Clause 14), which covers all
aspects of the service. The laboratory’s QA program should address the following issues:
a) It shall include periodic internal checks of equipment operations, reagent suitability, and various
performance checks (e.g. intra-laboratory comparison exercises, operator qualifications, sample
protocol, scoring, dose estimations, report generation, etc.).
b) It shall include periodic external checks of the laboratory’s operations. The external audits shall
include a review of the service laboratory’s documentation of equipment operations, reagent
suitability, and various performance checks (e.g. inter-laboratory comparison exercises, operator
qualifications, sample transport integrity and time for delivery, etc.).
7.2 Responsibility during service
The service laboratory shall provide necessary guidance, procedures, and timely reporting of the dose
assessment by cytogenetics in response to a request for service. The service activities shall address the
following issues:
a) the service laboratory shall have documentation, reviewed and endorsed by a qualified expert, for
example service laboratory radiobiologist or equivalent), which includes the following:
1) an instruction sheet to be sent to the requestor describing the shipping procedure (see Annex A);
2) a questionnaire that shall elicit patient consent and all available information regarding the
patient and the exposure scenario (see Annex B);
ISO 19238:2023(E)
3) step-by-step procedures for processing the blood sample from receipt of the sample to
reporting of the dose;
b) the service laboratory is not responsible for sample transport however, they should provide advice
regarding sample transfer. If required, a kit for the collection of at least 10 ml whole blood in tubes
containing lithium or sodium heparin as the anticoagulant shall be sent to the requestor with the
appropriately labelled and addressed packaging material for the return of the sample to the service
laboratory. The packaging shall conform to national and/or international regulations for the transit
of potentially infectious pathological specimens (see 14.2.4);
c) after receipt of the blood sample, the following steps shall be performed:
1) document the receipt of the blood sample (date, time, recipient);
2) check for conformity of the sample (blood volume, integrity of the tubes);
3) mark the blood sample with a unique code;
4) store samples at room temperature and document the place of storage until the setting up of
cultures;
5) set up cultures in parallel as soon as possible and document date, time, and operator;
6) document all the reagents used for culturing with appropriate lot numbers and expiry dates;
7) document the addition of reagents and the end of the culture (date, time, operator);
8) document the short- and long-term storage of the sample until slide making;
9) document the slide codes, number of slides, and location of storage;
10) document the results from scoring;
11) store the slides and case documents in an appropriate place for possible medico-legal
re-evaluation of the case;
d) the service laboratory shall interpret the results and prepare reports (see Annex C).
e) the service laboratory shall sustain a dialogue with and provide results to the requestor.
8 Confidentiality of personal information
8.1 Overview
Biological dosimetry investigations made by a service laboratory shall be undertaken in accordance
with national regulations regarding confidentiality. This would normally include the maintenance
of confidentiality of all of the patient's information including identity, medical data, etc. In addition,
the commercial confidentiality of the patient's employer and any other organizations involved in a
radiological accident/incident should be observed.
This requirement extends to 1) written, electronic, or verbal communications between the laboratory
and the person/organization requesting the analysis and receiving the report, and 2) the secure
protection of confidential information held within the organization where the service laboratory is
located.
ISO 19238:2023(E)
8.2 Applications of the principle of confidentiality
8.2.1 Delegation of responsibilities within the laboratory
The head of the laboratory may authorize a limited number of laboratory staff to deal with documents
related to the analysis. Persons with this authority shall have undertaken appropriate training and
have signed a commitment to confidentiality regarding their duties within the laboratory.
The laboratory head shall maintain the signed confidentiality agreements and ensure the security and
safety of all confidential documents.
8.2.2 Requests for analysis
Depending on national regulations, the request for an analysis should normally be made by a physician
representing the patient, or the analysis could be requested by another authority due to legal claims.
In all cases, the blood sampling for chromosome analysis shall be made with the patient’s informed
consent. The laboratory head, depending on the national regulations, may be required to maintain the
record of the patient's informed consent.
8.2.3 Transmission of confidential information
Whatever the chosen means of communication, confidentiality shall be ensured during the exchange of
information and reports between the service laboratory and the requestor of the analysis.
The laboratory head shall define all processes for information transmission and assurance of
confidentiality.
8.2.4 Anonymity of samples
The laboratory head shall have established protocols for maintaining the anonymity of samples. To avoid
the identification of the patient while guaranteeing the traceability of the analysis, the blood samples
should be coded upon arrival in the service laboratory. The coding is performed in an unambiguous way
according to a standard procedure. The same code is to be used for all the stages of analysis. The code
is assigned by an authorized person as defined in 7.2. Decoding, in
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