EN ISO 13304-1:2022
(Main)Radiological protection - Minimum criteria for electron paramagnetic resonance (EPR) spectroscopy for retrospective dosimetry of ionizing radiation - Part 1: General principles (ISO 13304-1:2020)
Radiological protection - Minimum criteria for electron paramagnetic resonance (EPR) spectroscopy for retrospective dosimetry of ionizing radiation - Part 1: General principles (ISO 13304-1:2020)
The primary purpose of this document is to provide minimum acceptable criteria required to establish a procedure for retrospective dosimetry by electron paramagnetic resonance spectroscopy and to report the results.
The second purpose is to facilitate the comparison of measurements related to absorbed dose estimation obtained in different laboratories.
This document covers the determination of absorbed dose in the measured material. It does not cover the calculation of dose to organs or to the body. It covers measurements in both biological and inanimate samples, and specifically:
a) based on inanimate environmental materials like glass, plastics, clothing fabrics, saccharides, etc., usually made at X-band microwave frequencies (8 GHz to 12 GHz);
b) in vitro tooth enamel using concentrated enamel in a sample tube, usually employing X-band frequency, but higher frequencies are also being considered;
c) in vivo tooth dosimetry, currently using L-band (1 GHz to 2 GHz), but higher frequencies are also being considered;
d) in vitro nail dosimetry using nail clippings measured principally at X-band, but higher frequencies are also being considered;
e) in vivo nail dosimetry with the measurements made at X-band on the intact finger or toe;
f) in vitro measurements of bone, usually employing X-band frequency, but higher frequencies are also being considered.
For biological samples, in vitro measurements are carried out in samples after their removal from the person or animal and under laboratory conditions, whereas the measurements in vivo are carried out without sample removal and may take place under field conditions.
NOTE The dose referred to in this document is the absorbed dose of ionizing radiation in the measured materials.
Strahlenschutz - Mindestanforderungen an die Elektronenspinresonanz (EPR-Spektroskopie) für die retrospektive Dosimetrie ionisierender Strahlung - Teil 1: Allgemeine Grundsätze (ISO 13304-1:2020)
Der Hauptzweck dieses Dokuments besteht darin, annehmbare Mindestkriterien festzulegen, die erforderlich sind, um ein Verfahren für die retrospektive Dosimetrie mittels paramagnetischer Elektronenresonanzspektroskopie einzuführen und die Ergebnisse zu berichten.
Der zweite Zweck ist die Erleichterung des Vergleichs von Messungen zur Abschätzung der Energiedosis, die in verschiedenen Labors durchgeführt wurden.
Dieses Dokument behandelt die Bestimmung der Energiedosis im gemessenen Material. Die Berechnung der Dosis für die Organe oder den Körper wird nicht behandelt. Es umfasst Messungen an biologischen und unbelebten Proben und insbesondere:
a) auf der Grundlage von unbelebten Umweltmaterialien wie Glas, Kunststoffen, Kleidungsstoffen, Sacchariden usw., die in der Regel bei X Band-Mikrowellenfrequenzen (8 GHz bis 12 GHz) hergestellt werden;
b) in-vitro-Zahnschmelz unter Verwendung von konzentriertem Zahnschmelz in einem Probenröhrchen, in der Regel mit X Band-Frequenz, aber auch höhere Frequenzen werden in Betracht gezogen;
c) in-vivo-Zahndosimetrie, derzeit mit L Band (1 GHz bis 2 GHz), aber auch höhere Frequenzen werden in Betracht gezogen;
d) in-vitro-Nageldosimetrie unter Verwendung von Nagelabschnitten, die hauptsächlich im X Band gemessen werden, aber auch höhere Frequenzen werden in Betracht gezogen;
e) in-vivo-Nageldosimetrie mit den Messungen im X Band an einem intakten Finger oder Zeh;
f) in-vitro-Messungen von Knochen, in der Regel unter Verwendung von X Band-Frequenzen, aber auch höhere Frequenzen werden in Betracht gezogen.
Bei biologischen Proben werden in vitro-Messungen an Proben nach deren Entnahme von der Person oder dem Tier und unter Laborbedingungen durchgeführt, während die Messungen in vivo ohne Probenentnahme durchgeführt werden und unter Feldbedingungen erfolgen dürfen.
ANMERKUNG Die Dosis, auf die in diesem Dokument Bezug genommen wird, ist die Energiedosis der ionisierenden Strahlung in den gemessenen Materialien.
Radioprotection - Critères minimaux pour la spectroscopie par résonance paramagnétique électronique (RPE) pour la dosimétrie rétrospective des rayonnements ionisants - Partie 1: Principes généraux (ISO 13304-1:2020)
Le but principal du présent document est de fournir un ensemble de critères minimaux acceptables requis pour établir un mode opératoire pour la dosimétrie rétrospective par spectroscopie par résonance paramagnétique électronique et pour présenter les résultats dans un rapport.
Son second objectif est de faciliter la comparaison des mesures associées à l'estimation de la dose absorbée de différents laboratoires.
Le présent document couvre la détermination de la dose absorbée dans le matériau mesuré. Il ne couvre pas le calcul de la dose délivrée aux organes ou à l'organisme entier. Il ne concerne que les mesurages de dosimétrie effectués sur des échantillons biologiques et des échantillons inertes, et plus particulièrement:
a) les mesurages de matériaux environnementaux inertes, tels que les verres, les polymères, les tissus pour vêtements, les saccharides, etc. généralement réalisés avec des fréquences micro‑ondes dans la bande X (8 GHz à 12 GHz);
b) les mesurages in vitro de prélèvement d'émail dentaire, placé dans un tube porte‑échantillon, et mesuré en général en bande X, mais des fréquences micro‑ondes plus élevées sont également considérées;
c) les mesurages in vivo de dents, réalisés actuellement en bande L (1 GHz à 2 GHz), mais des fréquences micro‑ondes plus élevées sont également considérées;
d) les mesurages in vitro de prélèvements d'ongles, effectués principalement en bande X, mais des fréquences micro‑ondes plus élevées sont également considérées;
e) les mesurages in vivo des ongles, effectués en bande X sur les ongles des doigts ou des orteils;
f) les mesurages in vitro de tissus osseux, réalisés en général en bande X, mais des fréquences micro‑ondes plus élevées sont également considérées.
En ce qui concerne les échantillons biologiques, les mesurages in vitro sont effectués sur des échantillons prélevés sur une personne ou un animal et dans des conditions de laboratoire, tandis que les mesurages in vivo sont réalisés sans prélèvement d'échantillon et peuvent s'effectuer sur le terrain.
NOTE La dose mentionnée dans le présent document est la dose absorbée de rayonnement ionisant dans les matériaux mesurés.
Radiološka zaščita - Minimalna merila za spektroskopijo z elektronsko paramagnetno resonanco (EPR) za retrospektivno dozimetrijo ionizirnega sevanja - 1. del: Splošna načela (ISO 13304-1:2020)
Glavni namen tega dokumenta je podati minimalna merila sprejemljivosti, ki so potrebna za vzpostavitev postopka za retrospektivno dozimetrijo s spektroskopijo z elektronsko paramagnetno resonanco in za poročanje rezultatov.
Namen je tudi olajšanje primerjave meritev v zvezi z oceno absorbirane doze, pridobljenih v drugih laboratorijih.
Ta dokument obravnava določevanje absorbirane doze v izmerjenem materialu. Ne obravnava izračuna doze, ki jo prejmejo organi ali telo. Zajema meritve tako v bioloških kot neživih vzorcih, zlasti:
a) na podlagi neživih okoljskih materialov, kot so steklo, plastika, tkanine, saharidi itd., ki so običajno izdelani pri mikrovalovnih frekvencah v pasu X (8 GHz do 12 GHz);
b) za meritve zobne sklenine in vitro z uporabo koncentrirane sklenine v tubi za vzorce, običajno pri frekvenci v pasu X, vendar so v obravnavi tudi višje frekvence;
c) za dozimetrijo zob in vivo, ki se trenutno izvaja v pasu L (1 GHz do 2 GHz), vendar so v obravnavi tudi višje frekvence;
d) za dozimetrijo nohtov in vitro z uporabo odrezkov nohtov, pri čemer se meritve izvajajo predvsem v pasu X, vendar so v obravnavi tudi višje frekvence;
e) za dozimetrijo nohtov in vivo z izvajanjem meritev v pasu X na nepoškodovanem prstu na roki ali nogi;
f) za meritve kosti in vitro, običajno pri frekvenci v pasu X, vendar so v obravnavi tudi višje frekvence.
Pri bioloških vzorcih se meritve in vitro izvajajo na vzorcih po njihovem odvzemu od osebe ali živali in v laboratorijskih pogojih, medtem ko se meritve in vivo izvajajo brez odvzema vzorca ter lahko potekajo na terenu.
OPOMBA: Doza, navedena v tem dokumentu, je absorbirana doza ionizirnega sevanja v izmerjenem materialu.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-marec-2023
Radiološka zaščita - Minimalna merila za spektroskopijo z elektronsko
paramagnetno resonanco (EPR) za retrospektivno dozimetrijo ionizirnega sevanja
- 1. del: Splošna načela (ISO 13304-1:2020)
Radiological protection - Minimum criteria for electron paramagnetic resonance (EPR)
spectroscopy for retrospective dosimetry of ionizing radiation - Part 1: General principles
(ISO 13304-1:2020)
Strahlenschutz - Mindestanforderungen an die Elektronenspinresonanz (EPR-
Spektroskopie) für die retrospektive Dosimetrie ionisierender Strahlung - Teil 1:
Allgemeine Grundsätze (ISO 13304-1:2020)
Radioprotection - Critères minimaux pour la spectroscopie par résonance
paramagnétique électronique (RPE) pour la dosimétrie rétrospective des rayonnements
ionisants - Partie 1: Principes généraux (ISO 13304-1:2020)
Ta slovenski standard je istoveten z: EN ISO 13304-1:2022
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 13304-1
EUROPEAN STANDARD
NORME EUROPÉENNE
December 2022
EUROPÄISCHE NORM
ICS 13.280; 17.240
English Version
Radiological protection - Minimum criteria for electron
paramagnetic resonance (EPR) spectroscopy for
retrospective dosimetry of ionizing radiation - Part 1:
General principles (ISO 13304-1:2020)
Radioprotection - Critères minimaux pour la Strahlenschutz - Mindestanforderungen an die
spectroscopie par résonance paramagnétique Elektronenspinresonanz (EPR-Spektroskopie) für die
électronique (RPE) pour la dosimétrie rétrospective retrospektive Dosimetrie ionisierender Strahlung - Teil
des rayonnements ionisants - Partie 1: Principes 1: Allgemeine Grundsätze (ISO 13304-1:2020)
généraux (ISO 13304-1:2020)
This European Standard was approved by CEN on 18 December 2022.
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
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 13304-1:2022 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
The text of ISO 13304-1:2020 has been prepared by Technical Committee ISO/TC 85 "Nuclear energy,
nuclear technologies, and radiological protection” of the International Organization for Standardization
(ISO) and has been taken over as EN ISO 13304-1:2022 by 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 June 2023, and conflicting national standards shall be
withdrawn at the latest by June 2023.
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.
Any feedback and questions on this document should be directed to the users’ national standards body.
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 13304-1:2020 has been approved by CEN as EN ISO 13304-1:2022 without any
modification.
INTERNATIONAL ISO
STANDARD 13304-1
Second edition
2020-07
Radiological protection — Minimum
criteria for electron paramagnetic
resonance (EPR) spectroscopy for
retrospective dosimetry of ionizing
radiation —
Part 1:
General principles
Radioprotection — Critères minimaux pour la spectroscopie par
résonance paramagnétique électronique (RPE) pour la dosimétrie
rétrospective des rayonnements ionisants —
Partie 1: Principes généraux
Reference number
ISO 13304-1:2020(E)
©
ISO 2020
ISO 13304-1:2020(E)
© ISO 2020
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
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CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
ISO 13304-1:2020(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Confidentiality and ethical considerations . 2
5 Laboratory safety requirements . 3
5.1 Magnetic field . 3
5.2 Electromagnetic frequency . 3
5.2.1 in vitro measurement . 3
5.2.2 in vivo measurement . 3
5.3 Biohazards from samples . 3
6 Collection/selection and identification of samples . 3
7 Transportation and storage of samples . 4
8 Preparation of samples. 4
9 Apparatus . 5
9.1 Principles of EPR spectroscopy . 5
9.2 Requirements for EPR spectrometers . 6
9.3 Requirements for the resonator . 6
9.4 Measurements of the background signals . 6
9.5 Spectrometer stability and monitoring/control of environmental conditions . 6
9.6 Baseline drift . 7
10 Measurements of the samples . 7
10.1 General principles . 7
10.2 Choice and optimization of the measurement parameters . 7
10.2.1 General. 7
10.2.2 Microwave-related parameters . 8
10.2.3 Magnetic field parameters . 8
10.2.4 Signal channel parameters . 8
10.3 Sample positioning and loading . 9
10.4 Microwave bridge tuning .10
10.5 Use of standard samples as field markers and amplitude monitors .10
10.6 Monitoring reproducibility .10
10.7 Procedure to measure anisotropic samples .10
10.8 Coding of spectra and samples .11
11 Determination of the absorbed dose in the samples .11
11.1 Determination of the radiation-induced signal intensity .11
11.2 Conversion of the EPR signal into an estimate of absorbed dose .11
11.2.1 Conversion of the EPR signal into an estimate of absorbed dose for in
vitro dosimetry . .11
11.2.2 Conversion of the EPR signal into an estimate of absorbed dose for in vivo
tooth dosimetry .12
12 Measurement uncertainty .12
13 Investigation of dose that has been questioned .12
14 Quality assurance (QA) and quality control (QC) .13
15 Minimum documentation requirements .14
Bibliography .16
ISO 13304-1:2020(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 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.
A list of all parts in the ISO 13304 series can be found on the ISO website.
This second edition cancels and replaces the first edition (ISO 13304-1:2013), of which it constitutes a
minor revision. The changes compared to the previous edition are as follows:
— inclusion of bibliographic references in the text;
— informative reference to ISO 13304-2 added;
— update of Bibliography.
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.
iv © ISO 2020 – All rights reserved
ISO 13304-1:2020(E)
Introduction
Electron paramagnetic resonance (EPR) has become an important approach for retrospective dosimetry
in any situation where dosimetric information is potentially incomplete or unknown for an individual.
It is now applied widely for retrospective evaluation of doses that were delivered at considerable times
in the past (e.g. EPR dosimetry is one of the methods of choice for retrospective evaluation of doses to
the involved populations from the atomic weapon exposures in Japan and after the Chernobyl accident)
and has received attention for use for triage after an incident in which large numbers of people have
[1] to [12]
potentially been exposed to clinically significant levels of radiation . Various materials may be
[13] to [41]
analysed by EPR to provide information on dose . Thus, EPR is a versatile tool for retrospective
dosimetry, pertinent as well for acute exposures (past or recent, whole or partial body) and prolonged
exposures. Doses estimated with EPR were mainly used to correlate the biological effect of ionizing
radiation to received dose, to validate other techniques or methodologies, to manage casualties, or
[42]
for forensic expertise for judicial authorities . It uses mainly biological tissues of the person as the
dosimeter and also can use materials from personal objects as well as those located in the immediate
environment. EPR dosimetry is based on the fundamental properties of ionizing radiation: the generation
of unpaired electron species (often but not exclusively free radicals) proportional to absorbed dose.
The technique of EPR specifically and sensitively detects the amount of unpaired electrons that have
sufficient stability to be observed after their generation; while the amount of the detectable unpaired
electrons is usually directly proportional to the amount that was generated, these species can react,
and therefore, the relationship between the intensity of the EPR signal and the radiation dose needs
to be established for each type of use. The most extensive use of the technique has been with calcified
[43] to [50]
tissue, especially with enamel from teeth . An IAEA technical report was published on the use
[51]
for tooth enamel . To extend the possibility of EPR retrospective dosimetry, new materials possibly
suitable for EPR dosimetry are regularly studied and associated protocols established. This document
is aimed to make this technique more widely available, more easily applicable and useful for dosimetry.
Specifically, this document proposes a methodological frame and recommendations to set up, validate,
and apply protocols from sample collection to dose reporting. The application of this document to ex
[52]
vivo human tooth enamel dosimetry is described in ISO 13304-2 .
INTERNATIONAL STANDARD ISO 13304-1:2020(E)
Radiological protection — Minimum criteria for electron
paramagnetic resonance (EPR) spectroscopy for
retrospective dosimetry of ionizing radiation —
Part 1:
General principles
1 Scope
The primary purpose of this document is to provide minimum acceptable criteria required to establish
a procedure for retrospective dosimetry by electron paramagnetic resonance spectroscopy and to
report the results.
The second purpose is to facilitate the comparison of measurements related to absorbed dose
estimation obtained in different laboratories.
This document covers the determination of absorbed dose in the measured material. It does not cover
the calculation of dose to organs or to the body. It covers measurements in both biological and inanimate
samples, and specifically:
a) based on inanimate environmental materials like glass, plastics, clothing fabrics, saccharides, etc.,
usually made at X-band microwave frequencies (8 GHz to 12 GHz);
b) in vitro tooth enamel using concentrated enamel in a sample tube, usually employing X-band
frequency, but higher frequencies are also being considered;
c) in vivo tooth dosimetry, currently using L-band (1 GHz to 2 GHz), but higher frequencies are also
being considered;
d) in vitro nail dosimetry using nail clippings measured principally at X-band, but higher frequencies
are also being considered;
e) in vivo nail dosimetry with the measurements made at X-band on the intact finger or toe;
f) in vitro measurements of bone, usually employing X-band frequency, but higher frequencies are
also being considered.
For biological samples, in vitro measurements are carried out in samples after their removal from the
person or animal and under laboratory conditions, whereas the measurements in vivo are carried out
without sample removal and may take place under field conditions.
NOTE The dose referred to in this document is the absorbed dose of ionizing radiation in the measured
materials.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO 13304-1:2020(E)
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
retrospective dosimetry (including early or emergency response)
dosimetry, usually at the level of the individual, carried out after an exposure using methods other than
conventional radiation dosimeters
3.2
electron paramagnetic resonance
EPR
electron spin resonance
ESR
magnetic resonance technique, which is similar to nuclear magnetic resonance (NMR) but based on the
net spin of unpaired electrons, such as free radicals and electron defects centres in matrices
Note 1 to entry: The terms EPR and ESR are essentially equivalent and are widely used. The term electron
magnetic resonance (EMR) also sometimes is used because it is analogous to nuclear magnetic resonance (NMR).
3.3
radical/paramagnetic centre
species with unpaired electron(s)
Note 1 to entry: Paired electrons have the same quantum state except for opposite spins; unpaired electrons
do not have a “partner” with the opposite spin. When the unpaired spin is on a molecule, it is usually termed a
radical; when the unpaired electron is in a matrix, it often is termed a paramagnetic centre.
3.4
in vivo measurement
measurement carried out within the living system, such as measurements of paramagnetic centres (3.3)
in teeth within the mouth
3.5
in vitro measurement
measurement carried out on materials outside the organism
Note 1 to entry: The term ex vivo also has been used in the literature for sample measured in vitro but irradiated
within the organism.
3.6
quality assurance
planned and systematic actions necessary to provide adequate confidence that a process, measurement,
or service satisfies given requirements for quality
3.7
quality control
planned and systematic actions intended to verify that systems and components conform with
predetermined requirements
4 Confidentiality and ethical considerations
All individual identifying information of persons who provided samples should not be attached to the
information on the samples and kept only in a secured place. The corresponding samples should be
identified by codes with indication only of parameters that are useful for scientific purposes and for
making decisions. Data linking the code to the person can be kept if they are done so in a secure manner,
with access limited to the persons in charge of the data.
2 © ISO 2020 – All rights reserved
ISO 13304-1:2020(E)
Where appropriate, permission for obtaining and measuring the samples should be obtained under the
rules of the jurisdiction where the samples are obtained.
5 Laboratory safety requirements
5.1 Magnetic field
With conventional EPR spectrometers, the magnetic field (for EPR signals with g-factor near 2,0,
typically 350 mT for X-band and 1 200 mT for Q-band) is restricted to the region between the pole caps
of the magnets, and therefore, there is no associated health risk (can affect watches or credit cards if
brought very close to the pole gap).
Due to the open nature of some in vivo EPR spectrometers, the magnetic field (for EPR signals with
g-factor near 2,0, 40 mT for L-band) combined with large gaps between the poles has the potential
to project the 0,5 mT line beyond the confines of the room. This line needs to be determined and
appropriate shielding placed for areas that exceed this limit and that are accessed by the general public.
The establishment of the 0,5 mT limit is based on concerns about potential effects on pacemakers,
which could pose a significant hazard from the magnetic fields that are employed with open in vivo EPR
spectrometers. The conventional limit is 0,5 mT (which is very conservative) and surveys should be
[53]
made to confirm that this field is not exceeded where a person with a pacemaker could be positioned .
Effects of modulation fields on tissues or tooth restorations are not a significant hazard.
5.2 Electromagnetic frequency
5.2.1 in vitro measurement
The configurations used for in vitro measurements have no hazard for exposure of operators, as
the spectrometer usually fully constrains the microwave to the sample with no significant amount
distributed outside of the resonator.
5.2.2 in vivo measurement
Measurements in vivo have the potential hazard of local heating of tissue. The operative safety limit
is that established for NMR in terms of permissible rates of energy absorption. In practice, this is a
potential hazard only at high incident microwave power levels — typically >1 W, which is at least a
factor of 3 greater than that in existing instruments.
5.3 Biohazards from samples
Biological samples measured in vitro should be handled in conformance to the rules of the jurisdiction
for routine practice for handling biological samples.
Measurements of teeth in vivo should follow the routines practiced for ordinary dentistry in regard to
potential contamination from subjects to operators or other subjects.
6 Collection/selection and identification of samples
All samples should be collected in as uniform manner as possible and the circumstances of the collection
noted, although this may not always be able to be controlled by the measuring laboratory. If prior
coordination between the collecting and the measuring laboratories is possible, requirements about the
sample collection, selection (of donors, location, or materials) and storage (sample holder, integrity of
the sample and of the container, temperature, light, UV) should be given. If information about samples
is available, keep record of them (this information can be about the location of the sample, origin or
history of the sample, information about donor, etc.). All samples should have a unique identifying code
associated with them.
ISO 13304-1:2020(E)
7 Transportation and storage of samples
If sample collection is made in a place other than the measuring laboratory, then samples should
be transported and stored under specified environmental conditions. These conditions should be
coordinated between the collecting and the measuring laboratories. Conditions of transportation
and storage of the sample may affect the integrity of the sample and also modify the quantity of
paramagnetic centres or the nature of the paramagnetic centres in the samples. Environmental
parameters such as light and other types of radiations (UV, X-rays, gamma), temperature, humidity,
oxygen, sample conditionings in water or disinfectant solution, for example, contamination (e.g. dust),
may significantly affect the nature and quantity of paramagnetic centres in the samples. Therefore,
specific attention should be paid as to the conditions of transportation and storage to avoid or limit as
much as possible the influence of environmental parameters on the samples. Details for transport and
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storage of tooth samples for ex vivo measurements are provided in ISO 13304-2 .
If possible, the influence of these parameters on the radiation-induced signal line shape and intensity
should be investigated to establish the optimum conditions for transportation or storage and to avoid
unnecessary precautions. When samples are known to be sensitive to one or several environmental
conditions or the influence of these parameters or samples is not known, it is highly recommended that
precautions are taken so as to avoid conditions that could affect the samples.
Transportation conditions, including dates, ways of transportation, and mode of control of
transportation conditions, should be recorded. Appropriate sample packaging should always be used to
prevent sample physical damage.
Procedures to avoid X-ray exposure of the sample during airport controls should be implemented. The
dose at the X-ray hand luggage control is of the order of the microgray, so it can be considered negligible
for some applications. If not, when the sample is transported in hand luggage, then authorization for
X-ray exemption should be obtained in advance in order to avoid hindrance at the airport security
controls. X-ray dose to the hold luggage can be higher. For shipping, appropriate labelling (including a
note that the package contains radiation-sensitive dosimeters and, therefore, should not be irradiated)
should be used. When this is not possible, unirradiated identical control samples or dosimeters should
be placed in the package.
After the samples are received, they should be stored under stable conditions and the temperature and
humidity should be monitored and recorded. Exposure to light should always be avoided.
8 Preparation of samples
Sample preparation should be performed according to an established and explicit protocol. Details for
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creation of a protocol for ex vivo measurements of tooth samples are provided in ISO 13304-2 .
For in vitro and ex vivo measurements, sample preparation is usually needed to accomplish several
goals, including: achieving a sample size that fits in the measurement tube; reducing anisotropy;
ensuring disinfection; eliminating paramagnetic impurities from the sample; drying the sample; and
stabilizing the EPR signals.
When required, preparation of the sample can be done by grinding, crushing, cutting, drilling, or other
mechanical treatments. During these operations, sample overheating should be avoided by using water
irrigation or other cooling systems. Metal contamination of the sample can be avoided by using hard
alloy tools.
Water irrigation of nails can influence the radiation-induced signal (RIS) and should be applied with care.
As needed, sterilization, cleaning, deproteination, and/or delipidation are performed using chemical
agents. Thermal treatment (annealing, freezing) can be used to accelerate or slow down recombination
of the radicals. Samples with significant amounts of moisture can be dried before the EPR measurements
to improve signal-to-noise ratio.
The setup of a protocol for sample preparation shall ensure no disturbing effect of the protocol on the
EPR signals (lineshape and intensity) used for dose estimation, and no generation of additional EPR
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ISO 13304-1:2020(E)
signals. When employing the additive dose method (see 11.2.1), it is very desirable to use protocols that
do not affect the radiation sensitivity.
The protocol should be described in details in documents, including: the duration of treatment, quality
of reagents, and the instrumentation used and its performance. All samples should be prepared
following the same protocol. Samples used for calibration have to be treated according to the same
protocol as the samples to be measured.
Any modification to the protocol should be noted and the influence of each modification evaluated (e.g.
power or frequency of ultrasonic bath, reagent quality).
All details of the procedures for each sample shall be recorded in a log of the history of the sample.
For measurements in vivo, there are no requirements for preparation of the samples. Depending
on the site that is measured, there may be a need to minimize moisture (especially when making
measurements in vivo in teeth) or to carry out some cleaning procedures (e.g. removing obvious
particulate matter from nails). Because of the limited ability to control environmental conditions fully
when making measurements in vivo, it is highly desirable to always utilize a standard sample that is in
place and with a known relationship to the sample volume so that factors that affect the measurements
(especially factors that affect the quality factor of the resonator) can be detected and accounted for in
the processing of the data.
9 Apparatus
9.1 Principles of EPR spectroscopy
EPR is a technique that specifically and sensitively detects unpaired electrons. It is based on the
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resonant absorption of electromagnetic energy for transitions between electron spin states . A static
magnetic field is applied that induces net absorption from transitions between spin states if there is a
vacant level to which the spin can flip. In a magnetic field, the different spin states result in different
energy levels, with the difference in the energy being proportional to the magnetic field. A transition
between these two levels can be induced by an appropriate electromagnetic field.
Currently, continuous wave (CW) EPR spectroscopy is usually used for EPR dosimetry. In an EPR
CW spectrometer, the resonance frequency is applied to a resonant structure and absorption of the
electromagnetic waves by a sample in the resonator is detected. Typically, the resonant condition is
reached by continuously changing the main magnetic field, while a fixed frequency is applied to the
resonator. As a result, an EPR spectrum of absorption versus magnetic field intensity is obtained. Other
methods of EPR signal detection such as pulsed EPR, fast scan EPR spectroscopy, etc. are potentially
available, but to date, these have not been shown to be more effective for dosimetry application than
CW EPR. So, considerations on EPR dosimetry in this document are restricted to CW EPR, although
most of the guidelines would be applicable to other types of EPR spectroscopy.
To improve the signal-to-noise ratio, modern EPR CW spectrometers employ high-frequency magnetic
field modulation in combination with phase-sensitive detection. As a result, the original spectral line
is produced not in the form of an absorption curve, but in the form of its first derivative. In modern
spectrometers, the EPR signal is recorded in digital form using a dedicated computer. In most
spectrometers, the computer also is used to control operation of the spectrometer, e.g. for setting
measurement parameters, tuning the resonator, acquiring the signal, saving the recorded spectrum to
disk, and preliminary spectra processing (such as digital filtering, baseline correction, etc.).
Depending on the magnetic field intensity and, respectively, the resonance frequency, the following
band frequencies are commonly used for EPR dosimetry.
— X-band usually is used for EPR in vitro dosimetry because of a good compromise between sensitivity,
sample size, and sensitivity to the presence of water.
— L-band is used mainly for in vivo tooth dosimetry because of the relatively low amount of non-
resonant absorption of the microwaves due to the presence of water in biological tissues. Q-band
ISO 13304-1:2020(E)
is mainly used in research connected with investigation of spectroscopic properties of materials
suitable for EPR dosimetry and has potential for being utilized for in vitro dosimetry. An advantage
of Q-band is that only a small sample mass is required for measurements and spectral components
can be better resolved in comparison with lower frequencies. On the other hand, such spectrometers
are not widely available, often are more complex to use, and may have a lower signal-to-noise ratio.
9.2 Requirements for EPR spectrometers
As EPR dosimetry often deals with small sample masses and low intensity signals, the sensitivity and
stability of the instruments are critical. Sensitivity and stability may be optimized by proper choice of
instrumental factors (such as selection of resonator, its tuning, and minimization of the microphonic
effects) and selection of the measurement parameters.
9.3 Requirements for the resonator
There are a number of different available designs in resonators, and therefore, it is important to choose
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the one that is optimal for the particular type of materials used for dosimetry . Critical aspects
include the sensitivity for the particular type of material, the available microwave power, and the
potential for placing the sample accurately in the most sensitive region of the resonator. It is essential
to systematically monitor the sensitivity and the accuracy of the various settings, including the
modulation amplitude. While theoretical considerations should be used to decide on the approximate
optimal settings, the final tests should be actual measurements with each pertinent parameter
empirically confirmed by measurements in which the parameter (e.g. the modulation amplitude) is
varied to find the setting that gives the maximum signal-to-noise ratio.
9.4 Measurements of the background signals
EPR signals may be originated by other paramagnetic centres in the resonator and also measurement
tube for in vitro analysis. Therefore, it is essential that measurements of empty resonator and empty
measurement tube be made under the same conditions as for samples used for dosimetry. The
background signal measured without sample tube may be used to ensure that the background is indeed
due to only the resonator.
The following types of the background signal of the resonator and baseline variation may be observed,
and if the type is identified, then one can more readily take proper actions to minimize its effect.
If a stable background signal is observed, then the resonator or the sample tube may be contaminated.
Careful cleaning of the resonator or the tube may diminish the effects of this type of background signal.
In the case where the background signal varies with repositioning or reinserting the sample and does
not have a consistent nature as expected with a paramagnetic contaminant, this is likely to be due to
“microphonics”. This can occur with both low frequency (e.g. L-band) and X-band. Dosimetry often
requires that the system be pushed to the limits of sensitivity, which makes the system susceptible to
microphonic noise. This appears to be due to mechanical effects, especially from modulation fields, but
is far from being fully understood. These effects sometimes can be minimized by careful attention to all
possible sources of vibrations and rigidity in the physical components and careful electrical grounding
of all components.
9.5 Spectrometer stability and monitoring/control of environmental conditions
The spectrometer should be allowed to reach a stable operating temperature in regard to both ambient
conditions and the EPR spectrometer’s cooling water. For maximum stability under demanding
operating conditions, such as any combination of high microwave power, high magnetic field modulation
amplitude, and variable temperature work, it is important to allow the system to equilibrate under the
same conditions as the experiment that is to be performed. One hour is usually adequate to achieve
temperature equilibrium.
6 © ISO 2020 – All rights reserved
ISO 13304-1:2020(E)
It is necessary to maintain a controlled environment for the best spectrometer performance. Air
flowing through the spectrometer, especially the cavity, may induce temperature fluctuations or
microphonics from sample vibration. Large fluctuations in the ambient temperature may degrade
performance by reducing the frequency stability of the cavity. Very humid environments may cause
water condensation. Condensation inside the cavity may be reduced by maintaining a constant purging
stream of dry nitrogen gas. Note that excessive gas flow rates may generate microphonic noise through
sample vibration.
Noise pick-up from electromagnetic fields may be encountered in some environments. It may be
possible to reduce such noise by shielding or perhaps by turning the noise source off if it is identified to
be generated by equipment near the spectrometer.
9.6 Baseline drift
Baseline drift is connected with stability of operation of the spectrometer. Baseline drift should be
minimized by optimization of operational conditions. Correction of the baseline drift effects on the
spectrum may be performed immediately after measurements with the use of the basic software of the
spectrometer, or it may be corrected during subsequent spectra processing of the radiation-induced
signal with the use of special software.
Linear baseline drift: The use of very high modulation amplitudes can produce large eddy currents
in the sidewalls of the resonator. These currents can interact with the magnetic field to produce a
torque on the resonator and create a resonant frequency shift. A linear-field-dependent or modulation-
amplitude-dependent baseline is indicative of such an effect. This phenomenon should not be observed
if the resonator end plates are properly fitted and torqued.
Slowly and randomly varying baseline: The use of high microwave power or large modulation fields can
heat the resonator and the sample. The ensuing thermal drifts in the coupling of the resonator, as well
as the frequency of the resonat
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