ISO 18090-1

Radiological protection — Characteristics of reference pulsed radiation — Part 1: Photon radiation

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.

Radioprotection — Caractéristiques des rayonnements pulsés de référence — Partie 1: Rayonnements photoniques

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.

General Information

• Status: Not Published
• ICS: 13.280 - Radiation protection
• Technical Committee: ISO/TC 85/SC 2 - Radiological protection
• Drafting Committee: ISO/TC 85/SC 2 - Radiological protection
• Current Stage: 6000 - International Standard under publication
• Start Date: 30-Apr-2026
• Completion Date: 23-May-2026

Relations

• Consolidates: FprEN ISO 18090-1 - Radiological protection - Characteristics of reference pulsed radiation - Part 1: Photon radiation (ISO/FDIS 18090-1:2026)
• Effective Date: 12-Feb-2026
• Consolidates: ISO 8000-51:2023 - Data quality — Part 51: Data governance: Exchange of data policy statements
• Effective Date: 28-Oct-2023
• Revises: ISO/TS 18090-1:2015 - Radiological protection — Characteristics of reference pulsed radiation — Part 1: Photon radiation
• Effective Date: 17-Jun-2023

Overview

ISO 18090-1: Radiological protection - Characteristics of reference pulsed radiation - Part 1: Photon radiation is an international standard developed by ISO focusing on the characteristics and measurement parameters for reference pulsed photon radiation. This document is essential for calibrating and testing radiation protection dosemeters and dose rate meters with regard to their behavior in pulsed X-ray fields-used extensively in medical diagnostics and other applications involving ionizing radiation.

The standard applies directly to pulsed X-radiation within a pulse duration range of 0.1 ms to 10 s, covering most medical and industrial diagnostic scenarios. ISO 18090-1 does not introduce new radiation qualities, but instead leverages parameters and methodologies specified in existing ISO and IEC standards, thus linking the characteristics of pulsed and continuous radiation fields.

Key Topics

• Time-Dependent Air Kerma and Voltage: Outlines requirements for measuring the air kerma rate (energy delivered by photon radiation) and tracking high voltage fluctuations during pulses.
• Uniformity and Spatial Characteristics: Specifies the assessment of beam uniformity (field uniformity) across a defined area to ensure reliable test conditions and equipment calibration.
• Pulse Parameters: Defines pulse duration, rise/fall times, plateau times, air kerma per pulse, and other important parameters of pulsed radiation fields.
• Calibration and Test Methods: Provides guidelines for measuring pulsed radiation characteristics using suitable instrumentation (e.g., semiconductor diodes, ionization chambers) with requirements for time and spatial resolution.
• Measurement Equivalence: Introduces the concept of using an equivalent trapezoidal pulse to standardize and compare actual measured pulses during calibration.
• Instrument Performance: Includes requirements for instrument sensitivity, field uniformity across the detector’s sensitive volume, and response consistency at varying air kerma rates.

Applications

ISO 18090-1 is primarily used to:

• Calibrate Radiation Protection Dosemeters: Ensures dosemeters and dose rate meters respond accurately to pulsed X-radiation, supporting compliance with occupational safety standards in environments with ionizing radiation.
• Test Medical Diagnostic Equipment: Applied by healthcare professionals and medical physicists for the accurate calibration of instruments used in diagnostic radiology, such as X-ray imaging systems.
• Support Regulatory Compliance: Provides a basis for assessing and verifying that radiation monitoring devices meet rigorous international protection standards.
• Design and Maintenance of X-ray Facilities: Used by engineers and facility managers to characterize and validate the radiation protection measures and test setups in research, medical, or industrial environments.

Related Standards

• ISO 4037 Series: Specifies reference radiation for calibrating dosemeters and the determination of response as a function of photon energy, forming the baseline for determining pulse parameters in ISO 18090-1.
• IEC 61267: Defines radiation conditions for medical diagnostic X-ray equipment, referenced for filtration and beam quality requirements.
• IEC/TS 62743 & IEC/TS 63050: Outline requirements and testing procedures for electronic dosemeters and their application to pulsed fields.
• ISO 4037-2:2019: Details dosimetry for radiation protection, including calibration of instruments and conversion coefficients for different reference qualities.

Practical Value

Implementing ISO 18090-1 increases the reliability and traceability of radiation protection measurements in pulsed X-ray fields. Adhering to this standard helps organizations and laboratories:

• Achieve accurate dose assessments in varying clinical and industrial scenarios where pulsed radiation is prevalent,
• Provide personnel and patient safety through validated dose monitoring,
• Maintain compliance with international radiological protection regulations,
• Facilitate cross-laboratory consistency and comparability in radiological measurements.

By standardizing the characterization and testing of pulsed photon radiation, ISO 18090-1 supports safety, accuracy, and innovation in radiological applications worldwide.

Standards Content (Sample)

DRAFT
International
Standard
ISO/DIS 18090-1
ISO/TC 85/SC 2
Radiological protection —
Secretariat: AFNOR
Characteristics of reference pulsed
Voting begins on:
radiation —
2025-07-02
Part 1:
Voting terminates on:
2025-09-24
Photon radiation
Radioprotection — Caractéristiques des champs de rayonnement
pulsés de référence —
Partie 1: Radiation de photons
ICS: 13.280
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS.
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Reference number
ISO/DIS 18090-1:2025(en)
DRAFT
ISO/DIS 18090-1:2025(en)
International
Standard
ISO/DIS 18090-1
ISO/TC 85/SC 2
Radiological protection —
Secretariat: AFNOR
Characteristics of reference pulsed
Voting begins on:
radiation —
Part 1:
Voting terminates on:
Photon radiation
Radioprotection — Caractéristiques des champs de rayonnement
pulsés de référence —
Partie 1: Radiation de photons
ICS: 13.280
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2025
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
BE CONSIDERED IN THE LIGHT OF THEIR
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
or ISO’s member body in the country of the requester.
NATIONAL REGULATIONS.
ISO copyright office
RECIPIENTS OF THIS DRAFT ARE INVITED
CP 401 • Ch. de Blandonnet 8
TO SUBMIT, WITH THEIR COMMENTS,
CH-1214 Vernier, Geneva
NOTIFICATION OF ANY RELEVANT PATENT
Phone: [phone]
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
ISO/DIS 18090-1:2025(en)
ii
ISO/DIS 18090-1:2025(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 .6
4.2.1 Requirements .6
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/DIS 18090-1:2025(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/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, Radioprotection.
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:
— 1 : clarification of the scope, which covers only the single pulse
— 4.4.2 : introduction of examples of other suitable instruments
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/DIS 18090-1:2025(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
[1]
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 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
DRAFT International Standard ISO/DIS 18090-1:2025(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
may also be applicable for much shorter pulses; one example is the air kerma of one pulse. Such a pulse
may 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
may not 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/DIS 18090-1:2025(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
ISO 4037-3, 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 3: Calibration of area
and personal dosemeters and the measurement of their response as a function of energy and angle of incidence
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 terms and definitions given in [external document reference xxx] and
the following 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 that is 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/DIS 18090-1:2025(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 , measured during the radiation pulse peak time
i
n
peak
U = U
pulse,peak,mean i
∑
n
peak
i=1
where
U is the i-th measured value;
i
n is the number of measurements of the X-ray tube voltage.
peak
3.7
pulse repetition frequency
f
pulse
number of pulses in a periodic pulse train divided by the duration of the train
Note 1 to entry: This version of this part of ISO 18090 deals only with single pulses, but it might be extended in the
future to repeated pulses, therefore, this definition is already given here.
[SOURCE: IEV 702-03-07, modified]
3.8
pulse train
discrete sequence of a finite number of pulses
Note 1 to entry: The sequence can be periodic or non-periodic.
[SOURCE: IEV 702-03-11, modified]
3.9
pulsed radiation
ionizing radiation which never has a constant dose rate at a given point
in space for time intervals longer than 10 s
3.10
radiation pulse base duration
radiation pulse base width
t
pulse, base
interval of time between the first and last instants at which the instantaneous air kerma rate value of the
equivalent trapezoidal pulse deviates from zero
Note 1 to entry: The value zero of the equivalent trapezoidal puls
...

FINAL DRAFT
International
Standard
ISO/FDIS 18090-1
ISO/TC 85/SC 2
Radiological protection —
Secretariat: AFNOR
Characteristics of reference pulsed
Voting begins on:
radiation —
2026-03-04
Part 1:
Voting terminates on:
2026-04-29
Photon radiation
Radioprotection — Caractéristiques des rayonnements pulsés de
référence —
Partie 1: Rayonnements photoniques
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/CEN PARALLEL PROCESSING LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
ISO/FDIS 18090-1:2026(en) © ISO 2026

FINAL DRAFT
ISO/FDIS 18090-1:2026(en)
International
Standard
ISO/FDIS 18090-1
ISO/TC 85/SC 2
Radiological protection —
Secretariat: AFNOR
Characteristics of reference pulsed
Voting begins on:
radiation —
Part 1:
Voting terminates on:
Photon radiation
Radioprotection — Caractéristiques des rayonnements pulsés de
référence —
Partie 1: Rayonnements photoniques
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2026
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/CEN PARALLEL PROCESSING
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
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 Reference number
ISO/FDIS 18090-1:2026(en) © ISO 2026

ii
ISO/FDIS 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/FDIS 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/FDIS 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
FINAL DRAFT International Standard ISO/FDIS 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/FDIS 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/FDIS 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 , measured during the radiation pulse peak time
i
n
peak
U  U
pulse,peak,mean i

n
peak
i1
where
U is the i-th measured value
i
n is the number of measurements of the X-ray tube voltage
peak
3.7
pulse repetition frequency
f
pulse
number of pulses in a periodic pulse train divided by the duration of the train
Note 1 to entry: This version of this part of ISO 18090 deals only with single pulses, but it might be extended in the
future to repeated pulses, therefore, this definition is already given here.
[SOURCE: IEV 702-03-07, modified]
3.8
pulsed radiation
ionizing radiation which never has a constant dose rate at a given point in
space for time intervals longer than 10 s
3.9
radiation pulse base duration
radiation pulse base width
t
pulse, base
interval of time between the first and last instants at which the instantaneous air kerma rate value of the
equivalent trapezoidal pulse deviates from zero
Note 1 to entry: The value zero of the equivalent trapezoidal pulse is equal to the baseline of the measured pulse.
3.10
radiation pulse duration
t
pulse
interval of time between the first and last instants at which the instantaneous air kerma rate value of the
equivalent trapezoidal pulse reaches 50 % of its maximum value
3.11
radiation pulse fall time
t
pulse, fall
interval of time between the last instants at which the instantaneous air kerma rate value of the equivalent
trapezoidal pulse reaches 80 % and 20 % of its maximum value

ISO/FDIS 18090-1:2026(en)
3.12
radiation pulse air kerma rate
K̇
a,pulse
quotient of the air kerma per radiation pulse (3.1) and the radiation pulse duration (3.11) at a point in the
photon radiation field
Note 1 to entry: The air kerma per radiation pulse can be measured either by an integral measurement with an
ionization chamber or time resolved by a suitable ins
...

ISO/FDIS 18090-1:2026(en)
ISO/TC 85/SC 2
Date: 2026-02-04
Secretariat: AFNOR
Date: 2026-xx
Radiological protection — Characteristics of reference pulsed
radiation — —
Part 1:
Photon radiation
Radioprotection — Caractéristiques des rayonnements pulsés de référence —
Partie 1: Rayonnements photoniques
FDIS stage
TTTTTThhhhhhiiiiiiss drs drs drs drs dr draaaaaafffffftttttt i i i i i is s s s s s susususususubbbbbbmmmmmmiiiiiitttttttttttteeeeeed d d d d d ttttttoooooo   aaaaaa   ppppppaaaaaarrrrrraaaaaallellellellellellel l l l l l vvvvvvooooootttttteeeeee i i i i i innnnnn   IIIIIISSSSSSOOOOOO,,,,,,   CCCCCCEEEEEEN.N.N.N.N.N.

ISO/FDIS 18090-1:2026(en)
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication
may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying,
or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO
at the address below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
EmailE-mail: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
ISO/FDIS 18090-1:2026(en)
Contents
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 2
4 Characteristics of reference pulsed radiation . 6
4.1 General . 6
4.2 Time-dependent air kerma rate characteristics of the radiation pulse . 6
4.3 Time-dependent high voltage characteristics of the radiation pulse . 8
4.4 Space dependent air kerma characteristics of the radiation pulse . 8
4.5 Filtration . 9
4.6 Equivalence of measured radiation pulse and trapezoidal pulse . 9
4.7 Constancy of air kerma rate during the pulse plateau time . 10
5 Dosimetry of pulsed reference radiation . 12
5.1 General requirements on the instrument . 12
5.2 Air kerma rate dependence of the instrument response . 12
5.3 Size of the sensitive volume of the instrument . 13
5.4 Air kerma of the radiation pulse . 13
5.5 Dose equivalent of the radiation pulse . 13
5.6 Radiation pulse air kerma rate . 13
5.7 Radiation pulse dose equivalent rate . 13
Annex A (informative) Diode-detector and associated amplifier . 14
Annex B (informative) Determination of the equivalent trapezoid radiation pulse . 16
Bibliography . 18

iii
ISO/FDIS 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 4.4.24.4.2.
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/FDIS 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 the
[2][2]
following ::
— — radiation pulse duration, t ;
pulse
— — radiation pulse air kerma rate, K� ;
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
ISO/FDIS 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) a) time-dependent behaviour of the air kerma rate of the pulse;
b) b) time-dependent behaviour of the X-ray tube high voltage during the pulse;
c) c) uniformity of the air kerma rate within a cross-sectional area of the radiation beam;
d) d) air kerma of one radiation pulse;
e) e) air kerma rate of the radiation pulse;
f) 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/FDIS 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 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 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 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 3.4
equivalent trapezoidal radiation pulse
trapezoidal radiation pulse that is considered to be equivalent to the given radiation pulse
3.5 3.5
field uniformity
F
uni
uniformity of the air kerma distribution determined across a defined area

𝐾𝐾 −𝐾𝐾
a,pulse,max a,pulse,min
𝐹𝐹 = 1−
uni
0,5 × (𝐾𝐾 +𝐾𝐾 )
a,pulse,max a,pulse,min
ISO/FDIS 18090-1:2026(en)
where
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 Funi = 1. No field uniformity, that is a variation of Ka, pulse between 0
and Ka, pulse, max, is equivalent to Funi = 0.
3.6 3.6
pulse peak mean voltage
U
pulse, peak, mean
mean value of the sequence of X-ray tube voltages, U , measured during the radiation pulse peak time
i
𝑛𝑛
peak
𝑈𝑈 = � 𝑈𝑈
pulse, peak, mean 𝑖𝑖
𝑛𝑛
peak
𝑖𝑖=1
where
Ui is the i-th measured value;
npeak is the number of measurements of the X-ray tube voltage.
3.7 3.7
pulse repetition frequency
f
pulse
number of pulses in a periodic pulse train divided by the duration of the train
Note 1 to entry: This version of this part of ISO 18090 deals only with single pulses, but it might be extended in the
future to repeated pulses, therefore, this definition is already given here.
[SOURCE: IEV 702-03-07, modified]
3.8 3.8
pulsed radiation
ionizing radiation which never has a constant dose rate at a given point in
space for time intervals longer than 10 s
3.9 3.9
radiation pulse base duration
radiation pulse base width
t
pulse, base
interval of time between the first and last instants at which the instantaneous air kerma rate value of the
equivalent trapezoidal pulse deviates from zero
Note 1 to entry: The value zero of the equivalent trapezoidal pulse is equal to the baseline of the measured pulse.
ISO/FDIS 18090-1:2026(en)
3.10 3.10
radiation pulse duration
t
pulse
interval of time between the first and last instants at which the instantaneous air kerma rate value of the
equivalent trapezoidal pulse reaches 50 % of its maximum value
3.11 3.11
radiation pulse fall time
t
pulse, fall
interval of time between the last instants at which the instantaneous air kerma rate value of the equivalent
trapezoidal pulse reaches 80 % and 20 % of its maximum value
3.12 3.12
radiation pulse air kerma rate
K�
a,pulse
quotient of the air kerma per radiation pulse (3.1(3.1)) and the radiation pulse duration (3.11(3.11)) at a point
in the photon radiation field
Note 1 to entry: The air kerma per radiation pulse can be measured either by an integral measurement with an
ionization chamber or time resolved by a suitable instrument, both calibrated in terms of air kerma.
3.13 3.13
radiation pulse dose equivalent rate
Ḣ
a,pulse
quotient of the dose equivalent per radiation pulse (3.3(3.3)) and the radiation pulse duration (3.11(3.11)) at a
point in the photon radiation field
Note 1 to entry: The dose equivalent per radiation pulse can be measured either by an integral measurement with an
ionization chamber or time resolved by a suitable instrument, both calibrated in terms of the relevant quantity.
3.14 3.14
radiation pulse peak voltage ripple
U
pulse, peak, ripple
standard deviation of the sequence of X-ray tube voltages, U , measured during the radiation pulse peak time
i
𝑛𝑛
peak
�
𝑈𝑈 = � (𝑈𝑈−𝑈𝑈 )
pulse, peak, ripple 𝑖𝑖 pulse, peak, mean
𝑛𝑛 − 1
peak
𝑖𝑖=1
where
U is the i-th measured value of the X-ray tube voltage;
i
n is the number of measurements;
peak
U is the pulse peak mean voltage.
pulse, peak, mean
3.15 3.15
pulse peak time
t
pulse, peak
interval of time between the first and last instants at which the instantaneous air kerma rate value of the
equivalent trapezoidal pulse reaches 80 % of its maximum value
ISO/FDIS 18090-1:2026(en)
Note 1 to entry: The radiation pulse peak time is the interval of time between the end of the rise time and the beginning
of the fall time of the equivalent trapezoidal pulse.
3.16 3.16
radiation pulse plateau time
t
pulse, plateau
interval of time at which the instantaneous air kerma rate value of the equivalent trapezoidal pulse reaches
its maximum value
3.17 3.17
radiation pulse rise time
t
pulse, rise
interval of time between the first instants at which the instantaneous air kerma rate value of the equivalent
trapezoidal pulse reaches 20 % and 80 % of its maximum value
3.18 3.18
trapezoidal pulse
unidirectional pulse having a constant gradient during increase from zero to its maximum value, remains for
a given time at this maximum value and having a constant gradient during its decrease from the maximum
value to zero
Note 1 to entry: See Figure 1Figure 1.
18090-1_ed1fig1.EPS
Key
A amplitude
B baseline
Figure 1 — Equivalent trapezoidal radiation pulse with the relevant parameters
ISO/FDIS 18090-1:2026(en)
4 Characteristics of reference pulsed radiation
4.1 General
The characterization of the radiation pulse requires the time resolved measurement of the air kerma rate and
the tube high voltage during the pulse and the space resolved measurement of the air kerma of the pulse. In
general, these measurements cannot be done with one single instrument.
4.2 Time-dependent air kerma rate characteristics of the radiation pulse
4.2.1 Requirements
The pulse rise time plus the pulse fall time shall not exceed 0,6 times the pulse duration, as given by
Formula (1)Formula (1)::
(1)
𝑡𝑡 +𝑡𝑡 ≤ 0,6 ×𝑡𝑡 (1)
pulse,rise pulse,fall pulse
The time resolved indicated values of the air kerma pulse rate, K� , and the radiation pulse duration, t ,
a,pulse,ind pulse
shall be determined.
4.2.2 Method of test
The time resolved indicated air kerma rate during the pulse, K� , shall be measured with an instrument
a,pulse,ind
which provides a time resolution of better than 2 % of the radiation pulse duration, t . It is important to
p
...

PROJET
Norme
internationale
ISO/DIS 18090-1
ISO/TC 85/SC 2
Radioprotection — Caractéristiques
Secrétariat: AFNOR
des rayonnements pulsés de
Début de vote:
référence —
2025-07-02
Partie 1:
Vote clos le:
2025-09-24
Rayonnements photoniques
Radiological protection — Characteristics of reference pulsed
radiation —
Part 1: Photon radiation
ICS: 13.280
CE DOCUMENT EST UN PROJET DIFFUSÉ
POUR OBSERVATIONS ET APPROBATION. IL
EST DONC SUSCEPTIBLE DE MODIFICATION
ET NE PEUT ÊTRE CITÉ COMME NORME
INTERNATIONALE AVANT SA PUBLICATION EN
TANT QUE TELLE.
Le présent document est distribué tel qu’il est parvenu du secrétariat
du comité. OUTRE LE FAIT D’ÊTRE EXAMINÉS POUR
ÉTABLIR S’ILS SONT ACCEPTABLES À DES
FINS INDUSTRIELLES, TECHNOLOGIQUES ET
COMMERCIALES, AINSI QUE DU POINT DE VUE
DES UTILISATEURS, LES PROJETS DE NORMES
INTERNATIONALES DOIVENT PARFOIS ÊTRE
TRAITEMENT PARALLÈLE ISO/CEN
CONSIDÉRÉS DU POINT DE VUE DE LEUR
POSSIBILITÉ DE DEVENIR DES NORMES
POUVANT SERVIR DE RÉFÉRENCE DANS LA
RÉGLEMENTATION NATIONALE.
LES DESTINATAIRES DU PRÉSENT PROJET
SONT INVITÉS À PRÉSENTER, AVEC LEURS
OBSERVATIONS, NOTIFICATION DES DROITS
DE PROPRIÉTÉ DONT ILS AURAIENT
ÉVENTUELLEMENT CONNAISSANCE
ET À FOURNIR UNE DOCUMENTATION
EXPLICATIVE.
Numéro de référence
ISO/DIS 18090-1:2025(fr)
ISO/TC 85/SC 2
ISO/DIS 18090-1:2025(fr)
ƒ–‡ǣʹͲʹͷǦͲͻǦʹͶ
ISO/DIS 18090-1:2025(F)
ȀͺͷȀʹ
‡…”±–ƒ”‹ƒ–ǣ 
Radioprotection — Caractéristiques des rayonnements pulsés
de référence — Partie 1 : Rayonnements photoniques
Radiological protection — Characteristics of reference pulsed radiation — Part 1: Photon radiation

ǣͳ͵ǤʹͺͲ
Avertissement
Ce document n’est pas une Norme internationale de l’ISO. Il est distribué pour examen et observations.
Ž‡•–•—•…‡’–‹„Ž‡†‡‘†‹ˆ‹…ƒ–‹‘•ƒ•’”±ƒ˜‹•‡–‡’‡—–²–”‡…‹–±…‘‡‘”‡‹–‡”ƒ–‹‘ƒŽ‡Ǥ
‡•†‡•–‹ƒ–ƒ‹”‡•†—’”±•‡–’”‘Œ‡–•‘–‹˜‹–±•’”±•‡–‡”ǡƒ˜‡…Ž‡—”•‘„•‡”˜ƒ–‹‘•ǡ‘–‹ˆ‹…ƒ–‹‘†‡•
†”‘‹–•†‡’”‘’”‹±–±†‘–‹Ž•ƒ—”ƒ‹‡–±˜‡–—‡ŽŽ‡‡–…‘ƒ‹••ƒ…‡‡–ˆ‘—”‹”—‡†‘…—‡–ƒ–‹‘
‡š’Ž‹…ƒ–‹˜‡Ǥ
DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2025
Tous droits réservés. Sauf prescription différente ou nécessité dans le contexte de sa mise en œuvre, aucune partie de cette
publication ne peut être reproduite ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique,
y compris la photocopie, ou la diffusion sur l’internet ou sur un intranet, sans autorisation écrite préalable. Une autorisation peut
être demandée à l’ISO à l’adresse ci-après ou au comité membre de l’ISO dans le pays du demandeur.
ISO copyright office
Case postale 401 • Ch. de Blandonnet 8
›’‡†—†‘…—‡–ǣ‘”‡‹–‡”ƒ–‹‘ƒŽ‡
CH-1214 Vernier, Genève
‘—•Ǧ–›’‡†—†‘…—‡–ǣ
Tél.: [phone]
–ƒ†‡†—†‘…—‡–ǣȋͶͲȌ“—²–‡
E-mail: [e-mail]
ƒ‰—‡†—†‘…—‡–ǣ 
Web: www.iso.org

Publié en Suisse


ii
ISO/DIS 18090-1:2025(fr)
Sommaire Page
Avant-propos . iv
Introduction . v
1 Domaine d’application . 1
2 Références normatives . 2
3 Termes et définitions . 2
4 Caractéristiques d’un champ pulsé de référence . 6
4.1 Généralités . 6
4.2 Caractéristiques de l’impulsion de rayonnement en matière de débit de kerma dans l’air en
fonction du temps . 6
4.2.1 Exigences . 6
4.2.2 Méthode d’essai . 7
4.2.3 Interprétation des résultats . 8
4.3 Caractéristiques de l’impulsion de rayonnement en matière de haute tension en fonction du
temps . 8
4.3.1 Exigence . 8
4.3.2 Méthode d’essai . 9
4.3.3 Interprétation des résultats . 9
4.4 Caractéristiques de l’impulsion de rayonnement en matière de débit de kerma dans l’air en
fonction de l’espace . 9
4.4.1 Exigence d’uniformité du champ sur toute la surface du faisceau . 9
4.4.2 Méthode d’essai . 9
4.4.3 Interprétation des résultats . 9
4.5 Filtration . 10
4.6 Équivalence de l’impulsion de rayonnement mesurée et de l’impulsion trapézoïdale . 10
4.6.1 Exigences . 10
4.6.2 Méthode d’essai . 10
4.6.3 Interprétation des résultats . 10
4.7 Constance du débit de kerma dans l’air pendant le temps de plateau de l’impulsion . 11
4.7.1 Exigence . 11
4.7.2 Méthode d’essai . 11
4.7.3 Interprétation des résultats . 11
5 Dosimétrie d’un rayonnement pulsé de référence . 13
5.1 Exigences générales relatives à l’instrument . 13
5.2 Dépendance de la réponse de l’instrument au débit de kerma dans l’air . 13
5.2.1 Généralités . 13
5.2.2 Exigence . 13
5.2.3 Méthode d’essai et interprétation des résultats . 13
5.3 Dimensions du volume utile de l’instrument . 13
5.4 Kerma dans l’air de l’impulsion de rayonnement . 13
5.5 Équivalent de dose de l’impulsion de rayonnement . 13
5.6 Débit de kerma dans l’air de l’impulsion de rayonnement . 14
5.7 Débit d’équivalent de dose de l’impulsion de rayonnement . 14
Annexe A (informative) Détecteur à diode et amplificateur associé . 15
Annexe B (informative) Détermination de l’impulsion de rayonnement trapézoïdale équivalente . 17
Bibliographie . 19
iii
ISO/DIS 18090-1:2025(fr)
Avant-propos
L’ISO (Organisation internationale de normalisation) est une fédération mondiale d’organismes nationaux
de normalisation (comités membres de l’ISO). L’élaboration des Normes internationales est en général confiée
aux comités techniques de l’ISO. Chaque comité membre intéressé par une étude a le droit de faire partie du
comité technique créé à cet effet. Les organisations internationales, gouvernementales et non gouvernementales,
en liaison avec l’ISO participent également aux travaux. L’ISO collabore étroitement avec la
Commission électrotechnique internationale (IEC) en ce qui concerne la normalisation électrotechnique.
Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont décrites
dans les Directives ISO/IEC, Partie 1. Il convient, en particulier de prendre note des différents critères
d’approbation requis pour les différents types de documents ISO. Le présent document a été rédigé
conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2
(voir www.iso.org/directives).
L’ISO attire l’attention sur le fait que la mise en application du présent document peut entraîner l’utilisation
d’un ou de plusieurs brevets. L’ISO ne prend pas position quant à la preuve, à la validité et à l’applicabilité de
tout droit de brevet revendiqué à cet égard. À la date de publication du présent document, l’ISO [avait/n’avait
pas] reçu notification qu’un ou plusieurs brevets pouvaient être nécessaires à sa mise en application.
Toutefois, il y a lieu d’avertir les responsables de la mise en application du présent document que
des informations plus récentes sont susceptibles de figurer dans la base de données de brevets, disponible
à l’adresse www.iso.org/brevets. L’ISO ne saurait être tenue pour responsable de ne pas avoir identifié de
tels droits de propriété.
Les appellations commerciales éventuellement mentionnées dans le présent document sont données pour
information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer un engagement.
Pour une explication de la nature volontaire des normes, la signification des termes et expressions spécifiques
de l’ISO liés à l’évaluation de la conformité, ou pour toute information au sujet de l’adhésion de l’ISO aux principes
de l’Organisation mondiale du commerce (OMC) concernant les obstacles techniques au commerce (OTC),
voir www.iso.org/avant-propos.
Le présent document a été élaboré par le comité technique ISO/TC 85, Énergie nucléaire, technologies
nucléaires et radioprotection, sous-comité SC 2, Radioprotection.
Cette première édition annule et remplace la première édition de l’ISO/TS 18090-1:2015, qui a fait l’objet
d’une révision technique.
Les principales modifications sont les suivantes :
— 1 : clarification du domaine d’application, qui couvre uniquement l’impulsion unique ;
— 4.4.2 : présentation d’autres exemples d’instruments adaptés.
Une liste de toutes les parties de la série ISO 18090 se trouve sur le site web de l’ISO.
Il convient que l’utilisateur adresse tout retour d’information ou toute question concernant le présent
document à l’organisme national de normalisation de son pays. Une liste exhaustive desdits organismes
se trouve à l’adresse www.iso.org/fr/members.html.
iv
ISO/DIS 18090-1:2025(fr)
Introduction
La spécification et la détermination des caractéristiques spéciales requises pour les dosimètres de
radioprotection électroniques à utiliser dans les champs pulsés de rayonnements ionisants ont été établies
dans des normes internationales, par exemple l’IEC/TS 62743 et l’IEC/TS 63050. Une condition préalable pour
l’IEC/TS 63050 est la disponibilité des champs de référence requis pour les rayonnements pulsés. Le présent
document fournit les informations nécessaires pour de tels champs de référence.
Le concept est fondé sur les normes existantes relatives aux qualités de rayonnements définies dans des
normes ISO et IEC. Il ajoute uniquement les paramètres du champ pulsé et fournit des recommandations pour
leur détermination. Par conséquent, aucune nouvelle qualité de rayonnement n’est définie ; seule la relation
entre les paramètres relatifs aux rayonnements pulsés et les paramètres relatifs aux rayonnements continus
[1]
est donnée. Les principaux paramètres requis pour les champs de rayonnement pulsés sont les suivants :
— durée de l’impulsion du rayonnement, t ;
impulsion
— débit de kerma dans l’air de l’impulsion de rayonnement, K̇ ;
a,impulsion
— kerma dans l’air par impulsion de rayonnement, K ;
a,impulsion
— pour des impulsions répétées, leur fréquence de répétition, f .
impulsion
Les paramètres d’impulsion ont été déterminés en utilisant une impulsion de rayonnement trapézoïdale
équivalente, qui est équivalente en matière de kerma dans l’air et de débit de kerma dans l’air. Le rayonnement
pulsé de référence est caractérisé par des écarts maximaux spécifiés de l’impulsion donnée par rapport
à l’impulsion de rayonnement trapézoïdale équivalente et par des exigences concernant la variation de qualité
de rayonnement pendant l’impulsion de rayonnement donnée.
Les paramètres d’impulsion par rapport aux grandeurs relatives au fantôme ont été déterminés en utilisant
des coefficients de conversion conformément à l’ISO 4037 (toutes les parties).
v
PROJET DE NORME INTERNATIONALE ISO/DIS 18090-1:2025(fr)
Radioprotection — Caractéristiques des rayonnements pulsés
de référence — Partie 1 : Rayonnements photoniques
1 Domaine d’application
Le présent document s’applique directement au rayonnement X pulsé ayant une durée d’impulsion comprise
entre 0,1 ms et 10 s. Cette plage 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 dits « flash » ou des lasers femtoseconde de hautes intensités.
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.
Le présent document 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. À ce point, il ne concerne que les caractéristiques des impulsions uniques. Les impulsions
uniques sont les plus difficiles à mesurer pour les dosimètres. Déterminer la dose pour les impulsions répétées
est plus simple, mais toujours plus difficile que pour les rayonnements continus, ainsi la performance des
dosimètres lors de la mesure d’impulsions répétées se trouve entre ces extrêmes. 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.
Le présent document ne définit pas de nouvelles qualités de rayonnement mais utilise les qualités
de rayonnement spécifiées dans les normes ISO et IEC existantes. Le présent document donne plutôt la relation
entre les paramètres relatifs à un rayonnement pulsé et les paramètres relatifs à un rayonnement continu
en précisant les qualités de rayonnement. Il 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.
Les paramètres d’impulsion par rapport aux grandeurs relatives au fantôme ont été déterminés en utilisant
des coefficients de conversion conformément à l’ISO 4037 (toutes les parties). Ceci est possible car les qualités
de rayonnement spécifiées dans des normes ISO et IEC existantes sont utilisées.
ISO/DIS 18090-1:2025(fr)
Une installation de référence à rayons X pulsés donnée est caractérisée par les plages de paramètres sur
lesquelles sont satisfaites l’ensemble des spécifications et des exigences du présent document. Par conséquent,
les installations de référence à rayons X pulsés ne peuvent pas toutes produire des impulsions couvrant
les mêmes plages de paramètres.
2 Références normatives
Les documents suivants sont cités dans le texte de sorte qu’ils constituent, pour tout ou partie de leur contenu,
des exigences du présent document. Pour les références datées, seule l’édition citée s’applique. Pour les références
non datées, la dernière édition du document de référence s’applique (y compris les éventuels amendements).
ISO 4037-1, Radioprotection — Rayonnements X et gamma de référence pour l’étalonnage des dosimètres et des
débitmètres, et pour la détermination de leur réponse en fonction de l’énergie des photons — Partie 1 :
Caractéristiques des rayonnements et méthodes de production.
ISO 4037-2:2019, Radioprotection — Rayonnements X et gamma de référence pour l’étalonnage des dosimètres
et des débitmètres, et pour la détermination de leur réponse en fonction de l’énergie des photons — Partie 2 :
Dosimétrie pour la radioprotection dans les gammes d’énergie de 8 keV à 1,3 MeV et de 4 MeV à 9 MeV.
ISO 4037-3, Radioprotection — Rayonnements X et gamma de référence pour l’étalonnage des dosimètres et des
débitmètres, et pour la détermination de leur réponse en fonction de l’énergie des photons — Partie 3 :
Étalonnage des dosimètres de zone et individuels et mesurage de leur réponse en fonction de l’énergie et de l’angle
d’incidence.
IEC 61267, Équipement de diagnostic médical à rayonnement X — Conditions de rayonnement pour utilisation
dans la détermination des caractéristiques.
3 Termes et définitions
Pour les besoins du présent document, les termes et les définitions de [xxx, référence du document cité]
ainsi que les suivants s’appliquent.
L’ISO et l’IEC tiennent à jour des bases de données terminologiques destinées à être utilisées en normalisation,
consultables aux adresses suivantes :
— ISO Online browsing platform : disponible à l’adresse https://www.iso.org/obp
— IEC Electropedia : disponible à l’adresse https://www.electropedia.org/
3.1
kerma dans l’air par impulsion de rayonnement
K
a, impulsion
valeur de kerma dans l’air pour une impulsion de rayonnement en un point du champ de rayonnement
photonique
3.2
rayonnement continu
rayonnement ionisant ayant un débit de dose constant en
un point donné de l’espace pendant des intervalles de temps supérieurs à 10 s
ISO/DIS 18090-1:2025(fr)
3.3
équivalent de dose par impulsion de rayonnement
H
impulsion
valeur d’équivalent de dose pour une impulsion de rayonnement en un point du champ de rayonnement
photonique
3.4
impulsion de rayonnement trapézoïdale équivalente
impulsion de rayonnement trapézoïdale qui est considérée comme étant équivalente à une impulsion
de rayonnement donnée
3.5
uniformité du champ
F
uni
uniformité de la distribution de kerma dans l’air déterminée dans une zone définie
KK−
a ,impulsion ,max a ,impulsion ,min
F =−1
uni
0,5×+KK
( )
a ,impulsion ,max a ,impulsion ,min

où
K est la valeur maximale de kerma dans l’air attribuée à une impulsion de rayonnement
a, impulsion, max
se produisant dans la zone définie ;
K est la valeur minimale de kerma dans l’air attribuée à une impulsion de rayonnement
a, impulsion, min
se produisant dans la zone définie
Note 1 à l’article : La zone définie peut être la totalité du diamètre du faisceau ou seulement des parties de celui-ci,
par exemple celles couvertes par le dosimètre en essai.
Note 2 à l’article : Une uniformité totale du champ est équivalente à Funi = 1. L’absence d’uniformité du champ, c’est-à-dire
une variation de K entre 0 et K , est équivalente à F = 0.
a, impulsion a, impulsion, max uni
3.6
tension crête moyenne de l’impulsion
U
impulsion, crête, moyenne
moyenne des valeurs de tensions, U , d’un tube à rayons X mesurées pendant la durée de la crête de l’impulsion
i
de rayonnement
n
crête
UU=
impulsion, crête, moyenne ∑ i
n
crête
i=1
où
U est la i-ème valeur mesurée ;
i
ncrête est le nombre de mesurages de la tension du tube à rayons X
ISO/DIS 18090-1:2025(fr)
3.7
fréquence de répétition des impulsions
f
impulsion
quotient du nombre d’impulsions dans un train d’impulsions périodiques par la durée de l’intervalle de temps
occupé par ce train
Note 1 à l’article : Cette version de la présente partie de l’ISO 18090 traite uniquement d’impulsions uniques, mais elle
pourrait être étendue dans le futur à des impulsions répétées ; par conséquent, cette définition est déjà donnée dans
le présent document.
[SOURCE : IEV 702-03-07, modifié]
3.8
train d’impulsions
suite d’impulsions en nombre fini
Note 1 à l’article : La suite peut être périodique ou non périodique.
[SOURCE : IEV 702-03-11, modifié]
3.9
rayonnement pulsé
rayonnement ionisant qui n’a jamais un débit de dose
constant en un point donné de l’espace pendant des intervalles de temps supérieurs à 10 s
3.10
durée de base d’une impulsion de rayonnement
largeur de base d’une impulsion de rayonnement
t
impulsion, base
durée de l’intervalle de temps entre les premier et dernier instants auxquels la valeur instantanée du débit
de kerma dans l’air de l’impulsion trapézoïdale équivalente s’écarte de zéro
Note 1 à l’article : La valeur zéro de l’impulsion trapézoïdale équivalente est égale à la ligne de base de l’impulsion mesurée.
3.11
durée d’une impulsion de rayonnement
largeur d’une impulsion de rayonnement
t
impulsion
durée de l’intervalle de temps entre les premier et dernier instants auxquels la valeur instantanée du débit
de kerma dans l’air de l’impulsion trapézoïdale équivalente atteint 50 % de sa valeur maximale
3.12
temps de descente d’une impulsion de rayonnement
t
impulsion, descente
durée de l’intervalle de temps entre les instants auxquels la valeur instantanée du débit de kerma dans l’air
de l’impulsion trapézoïdale équivalente atteint 80 % et 20 % de sa valeur maximale
3.13
débit de kerma dans l’air d’une impulsion de rayonnement
K̇
a,impulsion
quotient du kerma dans l’air par impulsion de rayonnement par la durée de l’impulsion de rayonnement
en un point du champ de rayonnement photonique
Note 1 à l’article : Le kerma dans l’air par impulsion de rayonnement peut être mesuré soit par une mesure intégrale
avec une chambre d’ionisation ou en fonction du temps par un instrument approprié, tous deux étalonnés concernant
le kerma dans l’air.
ISO/DIS 18090-1:2025(fr)
3.14
débit d’équivalent de dose d’une impulsion de rayonnement
Ḣ
a,impulsion
quotient de l’équivalent de dose par impulsion de rayonnement par la durée de l’impulsion de rayonnement
en un point du cham
...