oSIST prEN ISO 19238:2022

Radiological protection - Performance criteria for service laboratories performing biological dosimetry by cytogenetics - The dicentric assay (ISO/DIS 19238:2022)

Strahlenschutz - Durchführungskriterien für Dienstleistungslaboratorien zur Anwendung der biologischen Dosimetrie mittels zytogenetischer Verfahren - Dizentrischer Test (ISO/DIS 19238:2022)

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 behandelt Folgendes
a)   die Vertraulichkeit von persönlichen Angaben, in Bezug auf den Auftraggeber und das Dienstleistungslaboratorium,
b)   die Laboratorium-Sicherheitsanforderungen,
c)   die sinnvollen Kalibrierquellen (Kalibrierstrahler) und Kalibrierdosisbereiche zur Erstellung der Referenz-Dosis-Wirkungs-Kurven, die zur Dosisabschätzung anhand der Häufigkeit von instabilen Chromosomenaberrationen beitragen, und der Nachweisgrenzen,
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,
h)   informative Anhänge mit Musteranweisungen für Auftraggeber, Musterfragebogen, Musterbericht, Anpassung der Niedrigdosis-Wirkungs-Kurve nach dem Maximum-Likelihood-Verfahren und Berechnung des Fehlers der Dosisschätzung, Odds Ratio-Verfahren für Fälle einer vermuteten Exposition mit geringer Dosis, sowie eine Beispielberechnung und ein Musterdatenblatt für die Erfassung der Aberrationen.

Radioprotection - Critères de performance pour les laboratoires de service pratiquant la dosimétrie biologique par cytogénétique (ISO/DIS 19238:2022)

Radiološka zaščita - Merila za delovanje laboratorijev, ki izvajajo biološko dozimetrijo s citogenetiko - Diecentrična analiza (ISO/DIS 19238:2022)

General Information

• Status: Not Published
• Public Enquiry End Date: 21-Nov-2022
• ICS: 13.280 - Radiation protection
• ICS: 17.240 - Radiation measurements
• Technical Committee: I13 - Imaginarni 13
• Current Stage: 4020 - Public enquire (PE) (Adopted Project)
• Start Date: 22-Sep-2022
• Due Date: 09-Feb-2023
• Completion Date: 24-Oct-2022
• Ref Project: prEN ISO 19238 - Radiological protection - Performance criteria for service laboratories performing biological dosimetry by cytogenetics - The dicentric assay (ISO/DIS 19238:2022)

Relations

• Revised: SIST EN ISO 19238:2018 - Radiological protection - Performance criteria for service laboratories performing biological dosimetry by cytogenetics (ISO 19238:2014)
• Effective Date: 03-Aug-2022
• Revised: SIST EN ISO 19238:2018 - Radiological protection - Performance criteria for service laboratories performing biological dosimetry by cytogenetics (ISO 19238:2014)
• Effective Date: 18-Jan-2023

Standards Content (Sample)

SLOVENSKI STANDARD
oSIST prEN ISO 19238:2022
01-november-2022
Radiološka zaščita - Merila za delovanje laboratorijev, ki izvajajo biološko
dozimetrijo s citogenetiko - Diecentrična analiza (ISO/DIS 19238:2022)

Radiological protection - Performance criteria for service laboratories performing

biological dosimetry by cytogenetics - The dicentric assay (ISO/DIS 19238:2022)

Strahlenschutz - Durchführungskriterien für Dienstleistungslaboratorien zur Anwendung

der biologischen Dosimetrie mittels zytogenetischer Verfahren - Dizentrischer Test

(ISO/DIS 19238:2022)

Radioprotection - Critères de performance pour les laboratoires de service pratiquant la

dosimétrie biologique par cytogénétique (ISO/DIS 19238:2022)
Ta slovenski standard je istoveten z: prEN ISO 19238
ICS:
13.280 Varstvo pred sevanjem Radiation protection
17.240 Merjenje sevanja Radiation measurements
oSIST prEN ISO 19238:2022 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 19238:2022
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oSIST prEN ISO 19238:2022
DRAFT INTERNATIONAL STANDARD
ISO/DIS 19238
ISO/TC 85/SC 2 Secretariat: AFNOR
Voting begins on: Voting terminates on:
2022-08-31 2022-11-23
Radiological protection — Performance criteria for
service laboratories performing biological dosimetry by
cytogenetics - The dicentric assay
ICS: 17.240; 13.280
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
This document is circulated as received from the committee secretariat.
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oSIST prEN ISO 19238:2022
ISO/DIS 19238:2022(E)
DRAFT INTERNATIONAL STANDARD
ISO/DIS 19238
ISO/TC 85/SC 2 Secretariat: AFNOR
Voting begins on: Voting terminates on:
Radiological protection — Performance criteria for
service laboratories performing biological dosimetry by
cytogenetics - The dicentric assay
ICS: 17.240; 13.280
COPYRIGHT PROTECTED DOCUMENT
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NATIONAL REGULATIONS.
Website: www.iso.org ISO/DIS 19238:2022(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
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PROVIDE SUPPORTING DOCUMENTATION. © ISO 2022
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oSIST prEN ISO 19238:2022
ISO/DIS 19238:2022(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction .............................................................................................................................................................................................................................. vi

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 ........................................................................................................................................................... 4

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 ......................................................................................................... 6

8.2.1 Delegation of responsibilities within the laboratory......................................................................... 6

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 ........................................................................................................................................................ 7

9.1 Overview ...................................................................................................................................................................................................... 7

9.2 Microbiological safety requirements ................................................................................................................................. 8

9.3 Chemical safety ...................................................................................................................................................................................... 8

9.4 Optical safety requirements ....................................................................................................................................................... 9

9.5 Safety plan .................................................................................................................................................................................................. 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 .......................................................................................................................................................... 20

iii
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oSIST prEN ISO 19238:2022
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13 Reporting of results .......................................................................................................................................................................................20

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 ...........................................23

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 .......................................................................................................25

Annex B (informative) Sample questionnaire ........................................................................................................................................27

Annex C (informative) Sample of report .......................................................................................................................................................29

Annex D (informative) Fitting of the low-LET dose-response curve by the method of

maximum likelihood and calculating the error of dose estimate ................................................................31

Annex E (informative) Odds ratio method for cases of suspected exposure to a low dose ....................34

Annex F (informative) Decision threshold and detection limit ...........................................................................................36

Annex G Sample data sheet for recording aberrations ..............................................................................................................39

Bibliography .............................................................................................................................................................................................................................40

© ISO 2022 – All rights reserved
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oSIST prEN ISO 19238:2022
ISO/DIS 19238:2022(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 documents 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).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on 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 the following

URL: 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.

This second edition cancels and replaces the first edition (ISO 19238:2004), of which it constitutes a

minor revision.
© ISO 2022 – All rights reserved
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oSIST prEN ISO 19238:2022
ISO/DIS 19238:2022(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 proved 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 (e.g. 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

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

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

comply with the ISO guide to the expression of uncertainty in measurement (ISO/IEC Guide 98-1) and

the ISO 5725 on accuracy (trueness and precision) of measurement methods and results.

© ISO 2022 – All rights reserved
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oSIST prEN ISO 19238:2022
DRAFT INTERNATIONAL STANDARD ISO/DIS 19238:2022(E)
Radiological protection — Performance criteria for
service laboratories performing biological dosimetry by
cytogenetics - The 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 addresses

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-effect

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,

h) informative annexes containing sample instructions for requestor, sample questionnaire, sample

report, fitting of the low dose-response curve by the method of maximum likelihood and calculating

the error of the dose estimate, odds ratio method for cases of suspected exposure to a low dose, a

sample calculation and sample data sheet for recording aberrations.
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/
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

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oSIST prEN ISO 19238:2022
ISO/DIS 19238:2022(E)
3.2
background frequency/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 fragment.
3.4
centromere

specialized constricted region of a chromosome that appears during mitosis and joins together the

chromatid pair
3.5
confidence interval

range within which the true value of a statistical quantity lies with a specified probability

3.6
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
3.7
chromatid

either of the two strands of a duplicated chromosome that are joined by a single centromere and which

separate during cell division to become individual chromosomes
3.8
cytogenetics
A branch of genetics that deals with the study of chromosomes
3.9
dicentric

aberrant chromosome having two centromeres derived from the joining of parts from two broken

chromosomes, generally accompanied by an acentric fragment
3.10
interphase
period of a cell cycle between mitotic divisions
3.11
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
3.12
metaphase

stage of mitosis when the nuclear membrane is dissolved and the chromosomes are condensed to their

minimum lengths and aligned for division
3.13
mitotic index

percentage of cells of a cell population under division at a particular time of observation

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oSIST prEN ISO 19238:2022
ISO/DIS 19238:2022(E)
3.14
precision

concept employed to describe dispersion of measurements with respect to a measure of location or

central tendency
3.15
quality assurance (QA)

planned and systematic actions necessary to provide adequate confidence that a process, measurement,

or service satisfies given requirements for quality
3.16
quality control (QC)

planned and systematic actions intended to verify that systems and components conform with

predetermined requirements
3.17
Qdr

Chromosome aberration yield in cells with a chromosome aberration, typically calculated as the number

of dicentrics and/or rings divided by the number of metaphase spreads with either a dicentric or ring

3.18
service laboratory
laboratory performing biological dosimetry measurements
4 Abbreviated terms
BrdU Bromodeoxyuridine
Co Cobalt
covar Covariance
Cs Cesium
FBS Foetal bovine serum
FpG Fluorescence plus Giemsa
Gy Gray
H Null hypothesis
H Alternative hypothesis
HVL Half value layer
IAEA International Atomic Energy Agency
IEC International Electrochemical Commission
ISO International Organization for Standardization
IU International units
KCl Potassium chloride
LCL Lower confidence limits
MEM Minimum essential medium
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oSIST prEN ISO 19238:2022
ISO/DIS 19238:2022(E)
PHA Phytohaemagglutinin
...