SIST EN ISO 18090-1:2026

Radiological protection - Characteristics of reference pulsed radiation - Part 1: Photon radiation (ISO 18090-1:2026)

This document is directly applicable to pulsed X-radiation with pulse duration of 0,1 ms up to 10 s. This range covers the whole range used in medical diagnostics at the time of publication. Some specifications can also be applicable for much shorter pulses; one example is the air kerma of one pulse. Such a pulse can be produced, e.g. by X-ray flash units or high-intensity femtosecond-lasers. Other specifications are not applicable for much shorter pulses; one example is the time-dependent behaviour of the air kerma rate. This cannot be measurable for technical reasons as no suitable instrument is available, e.g. for pulses produced by a femtosecond-laser.
This document specifies the characteristics of reference pulsed radiation for calibrating and testing radiation protection dosemeters and dose rate meters with respect to their response to pulsed radiation. At this point, it is only concerned with the characteristics of single pulses. Single pulses are the most difficult for dosemeters to measure. Determining the dose for repeated pulses is easier, but still more difficult than for continuous radiation, i.e. the performance of the dosemeters when measuring repeated pulses lies between these extremes. The radiation characteristics includes the following:
time-dependent behaviour of the air kerma rate of the pulse;
time-dependent behaviour of the X-ray tube high voltage during the pulse;
uniformity of the air kerma rate within a cross-sectional area of the radiation beam;
air kerma of one radiation pulse;
air kerma rate of the radiation pulse;
repetition frequency.
This document does not define new radiation qualities but uses those radiation qualities specified in existing ISO and IEC standards. Instead, this document gives the link between the parameters for pulsed radiation and the parameters for continuous radiation specifying the radiation qualities. It does not specify specific values or series of values for the pulsed radiation field but specifies only those limits for the relevant pulsed radiation parameters that are required for calibrating dosemeters and dose rate meters and for determining their response depending on the said parameters.
The pulse parameters with respect to the phantom-related quantities were determined using conversion coefficients according to ISO 4037 (all parts). This is possible as the radiation qualities specified in existing ISO and IEC standards are used.
A given reference pulsed X-ray facility is characterized by the parameter ranges over which the full specifications and requirements according to this document are met. Therefore, not all reference pulsed X-ray facilities can produce pulses covering the same parameter ranges.

Strahlenschutz - Eigenschaften gepulster Referenzstrahlung - Teil 1: Photonenstrahlung (ISO 18090-1:2026)

Radioprotection - Caractéristiques des champs de rayonnement pulsés de référence - Partie 1: Radiation de photons (ISO 18090-1:2026)

L'ISO/TS 18090-1:2015 s'applique directement au rayonnement X pulsé ayant une durée d'impulsion comprise entre 0,1 ms et 10 s. Cela couvre toute la gamme utilisée en diagnostic médical au moment de la publication. Certaines spécifications peuvent également s'appliquer à des impulsions beaucoup plus courtes; un exemple est le kerma dans l'air d'une impulsion. Une telle impulsion peut être produite, par exemple, par des générateurs de rayons X « éclair » ou des lasers femtoseconde intenses. D'autres spécifications ne s'appliquent pas aux impulsions beaucoup plus courtes; un exemple est le comportement du débit kerma dans l'air en fonction du temps. Il se peut qu'il ne soit pas mesurable pour des raisons techniques, car aucun instrument approprié n'est disponible, par exemple pour des impulsions produites par un laser femtoseconde.
L'ISO/TS 18090-1:2015 spécifie les caractéristiques d'un rayonnement pulsé de référence pour l'étalonnage et les essais de dosimètres de radioprotection et de débitmètres de dose par rapport à leur réponse à un rayonnement pulsé. Les caractéristiques du rayonnement comprennent ce qui suit:
a) le comportement en fonction du temps du débit de kerma dans l'air de l'impulsion;
b) le comportement en fonction du temps de la haute tension du tube à rayons X pendant l'impulsion;
c) l'uniformité du débit de kerma dans l'air dans une section transversale du faisceau de rayonnement;
d) le kerma dans l'air d'une impulsion de rayonnement;
e) le débit de kerma dans l'air de l'impulsion de rayonnement;
f) la fréquence de répétition.
L'ISO/TS 18090-1:2015 ne définit pas de nouvelles qualités de rayonnement. Au lieu de cela, elle utilise les qualités de rayonnement spécifiées dans les normes ISO et IEC existantes. L'ISO/TS 18090-1:2015 indique la relation entre les paramètres relatifs à un rayonnement pulsé et les paramètres relatifs à un rayonnement continu spécifiant les qualités de rayonnement. Elle ne stipule pas de valeurs spécifiques ni de séries de valeurs pour le champ de rayonnement pulsé, mais spécifie uniquement les limites pour les paramètres pertinents de rayonnement pulsé qui sont requis pour l'étalonnage des dosimètres et des débitmètres de dose et pour la détermination de leur réponse en fonction desdits paramètres.

Radiološka zaščita - Značilnosti referenčnega pulznega sevanja - 1. del: Fotonsko sevanje (ISO 18090-1:2026)

Ta dokument je neposredno uporaben za pulzirajoče rentgensko sevanje s trajanjem pulza od 0,1 ms do 10 s. Ta razpon pokriva celoten razpon, ki se uporablja v medicinski diagnostiki v času objave. Nekatere specifikacije so lahko uporabne tudi za veliko krajše pulze; en primer je zračna kerma enega pulza. Takšen pulz se lahko proizvaja npr. z enotami za bliskovni rentgenski žarek ali visokointenzivnimi femtosekundnimi laserji. Druge specifikacije niso uporabne za veliko krajše pulze; en primer je časovno odvisno obnašanje hitrosti zračne kerme. To ni merljivo iz tehničnih razlogov, saj ni na voljo ustreznega instrumenta, npr. za pulze, proizvedene s femtosekundnim laserjem.
Ta dokument določa značilnosti referenčnega pulzirajočega sevanja za kalibracijo in testiranje dozimetrov za zaščito pred sevanjem in merilnikov hitrosti doze glede na njihov odziv na pulzirajoče sevanje. Na tej točki se ukvarja le z značilnostmi posameznih pulzov. Posamezni pulzi so najtežji za merjenje z dozimetri. Določanje doze za ponavljajoče se pulze je lažje, vendar še vedno težje kot za kontinuirano sevanje, tj. delovanje dozimetrov pri merjenju ponavljajočih se pulzov leži med tema skrajnostma. Značilnosti sevanja vključujejo naslednje:
- časovno odvisno obnašanje hitrosti zračne kerme pulza;
- časovno odvisno obnašanje visoke napetosti rentgenske cevi med pulzom;
- enakomernost hitrosti zračne kerme znotraj prečnega preseka sevalnega snopa;
- zračna kerma enega sevalnega pulza;
- hitrost zračne kerme sevalnega pulza;
- frekvenca ponavljanja.
Ta dokument ne določa novih kakovosti sevanja, temveč uporablja tiste kakovosti sevanja, ki so določene v obstoječih standardih ISO in IEC. Namesto tega dokument povezuje parametre za pulzirajoče sevanje s parametri za kontinuirano sevanje, ki določajo kakovosti sevanja. Ne določa specifičnih vrednosti ali serij vrednosti za polje pulzirajočega sevanja, temveč določa le tiste meje za ustrezne parametre pulzirajočega sevanja, ki so potrebne za kalibracijo dozimetrov in merilnikov hitrosti doze ter za določanje njihovega odziva glede na navedene parametre.
Parametri pulza v povezavi s količinami, povezanimi s fantomom, so bili določeni z uporabo pretvorbenih koeficientov v skladu z ISO 4037 (vsi deli). To je mogoče, saj se uporabljajo kakovosti sevanja, določene v obstoječih standardih ISO in IEC.
Določena referenčna pulzirajoča rentgenska naprava je opredeljena z razponi parametrov, znotraj katerih so izpolnjene vse specifikacije in zahteve v skladu s tem dokumentom. Zato ne morejo vse referenčne pulzirajoče rentgenske naprave proizvajati pulzov, ki pokrivajo enake razpone parametrov.

General Information

• Status: Published
• Public Enquiry End Date: 24-Sep-2025
• Publication Date: 18-Jun-2026
• ICS: 13.280 - Radiation protection
• Technical Committee: I13 - Imaginarni 13
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 11-Jun-2026
• Due Date: 16-Aug-2026
• Completion Date: 19-Jun-2026
• Ref Project: EN ISO 18090-1:2026 - Radiological protection - Characteristics of reference pulsed radiation - Part 1: Photon radiation (ISO 18090-1:2026)

Relations

• Revises: SIST-TS CEN ISO/TS 18090-1:2019 - Radiological protection - Characteristics of reference pulsed radiation - Part 1: Photon radiation (ISO/TS 18090-1:2015)
• Effective Date: 04-Oct-2023

Overview

SIST EN ISO 18090-1:2026 is a pivotal international standard that specifies the characteristics of reference pulsed photon radiation, focusing on its application in radiological protection. The primary intent of this standard is to describe and define requirements for reference pulsed X-radiation fields with pulse durations ranging from 0.1 milliseconds up to 10 seconds - a range broad enough to cover all typical conditions in medical diagnostics. These characteristics are critical for calibrating and testing radiation protection dosemeters and dose rate meters, ensuring their accuracy and reliability in environments where pulsed radiation is present.

Notably, the document addresses single pulses, which are particularly challenging for dosemeters to measure accurately, and provides guidance on the key parameters and methods essential for establishing reference conditions for pulsed photon radiation.

Key Topics

• Definition and Scope: Establishes the applicable pulse duration range and specifies that the standard refers to existing radiation qualities defined in ISO and IEC standards, rather than introducing new ones.
• Pulse Parameters: Outlines essential pulse characteristics that need to be measured and controlled, including:
  • Time-dependent air kerma rate (the energy delivered by radiation to air over the course of a pulse),
  • Time-dependent X-ray tube high voltage,
  • Uniformity of air kerma rate within the radiation beam,
  • Air kerma per pulse,
  • Air kerma rate,
  • Pulse repetition frequency.
• Testing and Calibration: Provides methodologies for measuring and interpreting the pulse characteristics to ensure compliance with the permitted parameter limits, which are crucial for dosemeter calibration.
• References to Existing Standards: Integrates parameters from ISO and IEC standards for radiation qualities, maintaining consistency with established dosimetry and calibration practices in radiological protection.

Applications

SIST EN ISO 18090-1:2026 serves a range of practical and vital applications in the fields of radiation protection and medical diagnostics:

• Calibration of Dosemeters: Enables reliable calibration of personal and area dosemeters and dose rate meters against reference pulsed radiation, ensuring safety and accuracy in radiation protection.
• Testing Instrument Performance: Allows for consistent testing of how radiation monitoring devices respond to pulsed versus continuous photon radiation, thus validating their suitability for environments with varying radiation profiles.
• Medical Diagnostics: Supports radiological facilities, especially those using pulsed X-ray technology (such as in fluoroscopy, mammography, or other imaging procedures), by providing reference fields for testing and compliance.
• Research and Development: Facilitates the development of new radiation measurement instruments and techniques by providing a harmonized set of test conditions for pulsed radiation.
• Regulatory Compliance: Assists in meeting national and international regulatory requirements for radiation protection instrumentation.

Related Standards

The framework and definitions within SIST EN ISO 18090-1:2026 are closely aligned with several foundational standards in radiological protection and dosimetry:

• ISO 4037 (all parts): Provides reference X and gamma radiation for calibrating dosemeters and dose rate meters, including conversion coefficients for phantom-related quantities.
• IEC 61267: Specifies requirements for radiation conditions used in calibrating medical diagnostic X-ray equipment.
• IEC/TS 62743 and IEC/TS 63050: Refer to the characteristics and testing of radiation protection dosemeters in pulsed fields.

By leveraging these related standards, SIST EN ISO 18090-1:2026 maintains compatibility and supports harmonized global practices in the measurement and control of pulsed photon radiation for radiological protection.

---

Keywords: Pulsed photon radiation, radiological protection, dosemeter calibration, air kerma rate, medical diagnostic X-ray, radiation standard, reference radiation fields, ISO 18090-1, radiation protection instrumentation, field uniformity, pulse duration.

Standards Content (Sample)

SLOVENSKI STANDARD
01-julij-2026
Radiološka zaščita - Značilnosti referenčnega impulznega sevanja - 1. del:
Fotonsko sevanje (ISO 18090-1:2026)
Radiological protection - Characteristics of reference pulsed radiation - Part 1: Photon
radiation (ISO 18090-1:2026)
Strahlenschutz - Eigenschaften gepulster Referenzstrahlung - Teil 1: Photonenstrahlung
(ISO 18090-1:2026)
Radioprotection - Caractéristiques des champs de rayonnement pulsés de référence -
Partie 1: Radiation de photons (ISO 18090-1:2026)
Ta slovenski standard je istoveten z: EN ISO 18090-1:2026
ICS:
13.280 Varstvo pred sevanjem Radiation protection
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 18090-1
EUROPEAN STANDARD
NORME EUROPÉENNE
June 2026
EUROPÄISCHE NORM
ICS 13.280 Supersedes CEN ISO/TS 18090-1:2019
English Version
Radiological protection - Characteristics of reference
pulsed radiation - Part 1: Photon radiation (ISO 18090-
1:2026)
Radioprotection - Caractéristiques des rayonnements Strahlenschutz - Eigenschaften gepulster
pulsés de référence - Partie 1: Rayonnements Referenzstrahlung - Teil 1: Photonenstrahlung (ISO
photoniques (ISO 18090-1:2026) 18090-1:2026)
This European Standard was approved by CEN on 30 May 2026.

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
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 18090-1:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 18090-1:2026) 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 December 2026, and conflicting national standards
shall be withdrawn at the latest by December 2026.
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 CEN ISO/TS 18090-1:2019.
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 18090-1:2026 has been approved by CEN as EN ISO 18090-1:2026 without any
modification.
International
Standard
ISO 18090-1
First edition
Radiological protection —
2026-05
Characteristics of reference pulsed
radiation —
Part 1:
Photon radiation
Radioprotection — Caractéristiques des rayonnements pulsés de
référence —
Partie 1: Rayonnements photoniques
Reference number
ISO 18090-1:2026(en) © ISO 2026

ISO 18090-1:2026(en)
© ISO 2026
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: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
ISO 18090-1:2026(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 2
4 Characteristics of reference pulsed radiation . 5
4.1 General .5
4.2 Time-dependent air kerma rate characteristics of the radiation pulse .5
4.2.1 Requirements .5
4.2.2 Method of test .6
4.2.3 Interpretation of the results .7
4.3 Time-dependent high voltage characteristics of the radiation pulse .7
4.3.1 Requirement .7
4.3.2 Method of test .7
4.3.3 Interpretation of the results .7
4.4 Space dependent air kerma characteristics of the radiation pulse .7
4.4.1 Requirement on field uniformity across the beam area .7
4.4.2 Method of test .8
4.4.3 Interpretation of the results .8
4.5 Filtration .8
4.6 Equivalence of measured radiation pulse and trapezoidal pulse .8
4.6.1 Requirements .8
4.6.2 Method of test .8
4.6.3 Interpretation of the results .9
4.7 Constancy of air kerma rate during the pulse plateau time .9
4.7.1 Requirement .9
4.7.2 Method of test .9
4.7.3 Interpretation of results .9
5 Dosimetry of pulsed reference radiation .11
5.1 General requirements on the instrument .11
5.2 Air kerma rate dependence of the instrument response .11
5.2.1 General .11
5.2.2 Requirement .11
5.2.3 Method of test and interpretation of the results .11
5.3 Size of the sensitive volume of the instrument . 12
5.4 Air kerma of the radiation pulse . 12
5.5 Dose equivalent of the radiation pulse. 12
5.6 Radiation pulse air kerma rate . 12
5.7 Radiation pulse dose equivalent rate . 12
Annex A (informative) Diode-detector and associated amplifier .13
Annex B (informative) Determination of the equivalent trapezoid radiation pulse .15
Bibliography . 17

iii
ISO 18090-1:2026(en)
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).
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 not 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 first edition cancels and replaces the first edition of ISO/TS 18090-1:2015, which has been technically
revised.
The main changes are as follows:
— clarification of the scope, which covers only the single pulse;
— introduction of examples of other suitable instruments in 4.4.2.
A list of all parts in the ISO 18090 series can be found on the ISO website.
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 18090-1:2026(en)
Introduction
The specification and determination of the special characteristics required for electronic radiation
protection dosemeters to be used in pulsed fields of ionizing radiation have been laid down in International
Standards, for example IEC/TS 62743 and IEC/TS 63050. A prerequisite for IEC/TS 63050 is the availability
of the required reference fields for pulsed radiation. This document provides the necessary information for
such reference fields.
The concept is based on the existing standards for radiation qualities defined in ISO and IEC standards. It
only adds the parameters of the pulsed field and gives some guidance for their determination. Therefore,
no new radiation qualities are defined, only the link between the parameters for pulsed radiation and the
parameters for continuous radiation are given. The main required parameters for pulsed radiation fields are
[2]
the following :
— radiation pulse duration, t ;
pulse
— radiation pulse air kerma rate, K̇ ;
a,pulse
— air kerma per radiation pulse, K ;
a,pulse
— for repeated pulses, their pulse repetition frequency, f .
pulse
The pulse parameters were determined by using an equivalent trapezoidal radiation pulse, which is
equivalent with respect to air kerma and air kerma rate. Reference pulsed radiation is characterized by
specified maximum deviations of the given pulse from the equivalent trapezoidal radiation pulse and by
requirements concerning the change of radiation quality during the given radiation pulse.
The pulse parameters with respect to the phantom related quantities were determined using conversion
coefficients according to ISO 4037 (all parts).

v
International Standard ISO 18090-1:2026(en)
Radiological protection — Characteristics of reference pulsed
radiation —
Part 1:
Photon radiation
1 Scope
This document is directly applicable to pulsed X-radiation with pulse duration of 0,1 ms up to 10 s. This
range covers the whole range used in medical diagnostics at the time of publication. Some specifications
can also be applicable for much shorter pulses; one example is the air kerma of one pulse. Such a pulse can
be produced, e.g. by X-ray flash units or high-intensity femtosecond-lasers. Other specifications are not
applicable for much shorter pulses; one example is the time-dependent behaviour of the air kerma rate. This
cannot be measurable for technical reasons as no suitable instrument is available, e.g. for pulses produced
by a femtosecond-laser.
This document specifies the characteristics of reference pulsed radiation for calibrating and testing
radiation protection dosemeters and dose rate meters with respect to their response to pulsed radiation. At
this point, it is only concerned with the characteristics of single pulses. Single pulses are the most difficult
for dosemeters to measure. Determining the dose for repeated pulses is easier, but still more difficult than
for continuous radiation, i.e. the performance of the dosemeters when measuring repeated pulses lies
between these extremes. The radiation characteristics includes the following:
a) time-dependent behaviour of the air kerma rate of the pulse;
b) time-dependent behaviour of the X-ray tube high voltage during the pulse;
c) uniformity of the air kerma rate within a cross-sectional area of the radiation beam;
d) air kerma of one radiation pulse;
e) air kerma rate of the radiation pulse;
f) repetition frequency.
This document does not define new radiation qualities but uses those radiation qualities specified in existing
ISO and IEC standards. Instead, this document gives the link between the parameters for pulsed radiation
and the parameters for continuous radiation specifying the radiation qualities. It does not specify specific
values or series of values for the pulsed radiation field but specifies only those limits for the relevant pulsed
radiation parameters that are required for calibrating dosemeters and dose rate meters and for determining
their response depending on the said parameters.
The pulse parameters with respect to the phantom-related quantities were determined using conversion
coefficients according to ISO 4037 (all parts). This is possible as the radiation qualities specified in existing
ISO and IEC standards are used.
A given reference pulsed X-ray facility is characterized by the parameter ranges over which the full
specifications and requirements according to this document are met. Therefore, not all reference pulsed
X-ray facilities can produce pulses covering the same parameter ranges.

ISO 18090-1:2026(en)
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 4037-1, Radiological protection — X and gamma reference radiation for calibrating dosemeters and doserate
meters and for determining their response as a function of photon energy — Part 1: Radiation characteristics
and production methods
ISO 4037-2:2019, Radiological protection — X and gamma reference radiation for calibrating dosemeters and
doserate meters and for determining their response as a function of photon energy — Part 2: Dosimetry for
radiation protection over the energy ranges from 8 keV to 1,3 MeV and 4 MeV to 9 MeV
IEC 61267, Medical diagnostic X-ray equipment — Radiation conditions for use in the determination of
characteristics
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology 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
air kerma per radiation pulse
K
a, pulse
air kerma value of one radiation pulse at a point in the photon radiation field
3.2
continuous radiation
ionizing radiation with a constant dose rate at a given point in space for
time intervals longer than 10 s
3.3
dose equivalent per radiation pulse
H
pulse
dose equivalent value of one radiation pulse at a point in the photon radiation field
3.4
equivalent trapezoidal radiation pulse
trapezoidal radiation pulse considered to be equivalent to the given radiation pulse
3.5
field uniformity
F
uni
uniformity of the air kerma distribution determined across a defined area
KK
ap,,ulse maxa,,pulsemin
F 1
uni
05, KK

ap,,ulse maxa,,pulse mmin
where
ISO 18090-1:2026(en)
K is the maximum air kerma value attributed to one radiation pulse occurring across the
a, pulse, max
defined area
K is the minimum air kerma value attributed to one radiation pulse occurring across the
a, pulse, min
defined area
Note 1 to entry: The defined area can be the whole beam diameter or only parts of it, e.g. those covered by the
dosemeter under test.
Note 2 to entry: Full field uniformity is equivalent to F = 1. No field uniformity, that is a variation of K between 0
uni a, pulse
and K , is equivalent to F = 0.
a, pulse, max uni
3.6
pulse peak mean voltage
U
pulse, peak, mean
mean value of the sequence of X-ray tube voltages, U ,
...