prEN ISO 18090-1

SLOVENSKI STANDARD
01-september-2025
Radiološka zaščita - Značilnosti referenčnega impulznega sevanja - 1. del:
Fotonsko sevanje (ISO/DIS 18090-1:2025)
Radiological protection - Characteristics of reference pulsed radiation - Part 1: Photon
radiation (ISO/DIS 18090-1:2025)
Radioprotection - Caractéristiques des champs de rayonnement pulsés de référence -
Partie 1: Radiation de photons (ISO/DIS 18090-1:2025)
Ta slovenski standard je istoveten z: prEN ISO 18090-1
ICS:
13.280 Varstvo pred sevanjem Radiation protection
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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.
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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
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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 co
...