EN ISO 4037-4:2021

SLOVENSKI STANDARD
01-april-2021
Radiološka zaščita - Referenčno sevanje z rentgenskimi in gama žarki za
kalibracijo dozimetrov in merilnikov doze sevanja ter za ugotavljanje njihovega
odzivanja kot funkcije fotonske energije - 4. del: Kalibriranje zunanjih in osebnih
dozimetrov v območjih z nizko energijo rentgenskega referenčnega sevanja (ISO
4037-4:2019)
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 4: Calibration of area and personal dosemeters in low energy X reference radiation
fields (ISO 4037-4:2019)
Strahlenschutz - Röntgen- und Gamma-Referenzstrahlungsfelder zur Kalibrierung von
Dosimetern und Dosisleistungsmessgeräten und zur Bestimmung ihres
Ansprechvermögens als Funktion der Photonenenergie - Teil 4: Kalibrierung von Orts-
und Personendosimetern in niedrigenergetischen Röntgen-Referenzstrahlungsfeldern
(ISO 4037-4:2019)
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 4: Étalonnage des dosimètres de zone et individuels dans
des champs de référence X de faible énergie (ISO 4037-4:2019)
Ta slovenski standard je istoveten z: EN ISO 4037-4:2021
ICS:
13.280 Varstvo pred sevanjem Radiation protection
17.240 Merjenje sevanja Radiation measurements
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 4037-4
EUROPEAN STANDARD
NORME EUROPÉENNE
February 2021
EUROPÄISCHE NORM
ICS 17.240
English Version
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 4: Calibration of area and personal dosemeters in
low energy X reference radiation fields (ISO 4037-4:2019)
Radioprotection - Rayonnements X et gamma de Strahlenschutz - Röntgen- und Gamma-
référence pour l'étalonnage des dosimètres et des Referenzstrahlungsfelder zur Kalibrierung von
débitmètres et pour la détermination de leur réponse Dosimetern und Dosisleistungsmessgeräten und zur
en fonction de l'énergie des photons - Partie 4: Bestimmung ihres Ansprechvermögens als Funktion
Étalonnage des dosimètres de zone et individuels dans der Photonenenergie - Teil 4: Kalibrierung von Orts-
des champs de référence X de faible énergie (ISO 4037- und Personendosimetern in niedrigenergetischen
4:2019) Röntgen-Referenzstrahlungsfeldern (ISO 4037-4:2019)
This European Standard was approved by CEN on 18 January 2021.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 4037-4:2021 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
The text of ISO 4037-4:2019 has been prepared by Technical Committee ISO/TC 85 "Nuclear energy,
nuclear technologies, and radiological protection” of the International Organization for Standardization
(ISO) and has been taken over as EN ISO 4037-4:2021 by Technical Committee CEN/TC 430 “Nuclear
energy, nuclear technologies, and radiological protection” the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by August 2021, and conflicting national standards shall
be withdrawn at the latest by August 2021.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 4037-4:2019 has been approved by CEN as EN ISO 4037-4:2021 without any
modification.
INTERNATIONAL ISO
STANDARD 4037-4
Second edition
2019-01
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 4:
Calibration of area and personal
dosemeters in low energy X reference
radiation fields
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 4: Étalonnage des dosimètres de zone et individuels dans des
champs de référence X de faible énergie
Reference number
ISO 4037-4:2019(E)
©
ISO 2019
ISO 4037-4:2019(E)
© ISO 2019
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
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Published in Switzerland
ii © ISO 2019 – All rights reserved

ISO 4037-4:2019(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols (and abbreviated terms) . 2
5 General procedures for calibrating and determining response . 3
6 Characterisation and production of low energy X-ray reference radiations .3
6.1 General . 3
6.2 Tube potential . 4
6.3 Spectral fluence and conversion coefficients . 4
7 Dosimetry of low energy reference radiations . 4
7.1 General . 4
7.2 Stability check facility . 4
8 Calibration and determination of the response as a function of photon energy and
angle of radiation incidence . 4
8.1 General . 4
8.2 Selection of calibration method . 5
8.3 Calibration by using reference instruments for K . 5
a
8.3.1 General. 5
8.3.2 Conventional quantity value of the air kerma . 5
8.3.3 Conventional quantity value of the dose equivalent quantities H (0,07)
p
and H'(0,07) . 6
8.3.4 Conventional quantity value of the dose equivalent quantities H (10) or
p
H*(10) and H (3) or H'(3) . 6
p
8.3.5 Performing the calibration . 8
8.4 Calibration by using reference instruments which measure the ICRU dose
equivalent quantities . 8
8.4.1 General. 8
8.4.2 Conventional quantity value of the dose equivalent quantities H (10) or
p
H*(10) and H (3) or H'(3) . 9
p
8.4.3 Performing the calibration .10
8.5 Statement of uncertainty .11
Annex A (normative) Correction for air density .12
Bibliography .18
ISO 4037-4:2019(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: www .iso .org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technologies
and radiological protection, Subcommittee SC 2, Radiological protection.
This second edition cancels and replaces the first edition (ISO 4037-4:2004), which has been technically
revised.
A list of all the parts in the ISO 4037 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 2019 – All rights reserved

ISO 4037-4:2019(E)
Introduction
The maintenance release of this document adjusts this fourth part to the second edition of the first
three parts. This includes the improvements on high voltage generators from 1996 to 2017 (e.g., the
use of high frequency switching supplies providing nearly constant potential), and the spectral
measurements at irradiation facilities equipped with such generators (e.g., the catalogue of X-ray
[1]
spectra by Ankerhold ). It also incorporates all published information with the aim to adjust the
requirements for the technical parameters of the reference fields to the targeted overall uncertainty of
about 6 % to 10 % for the phantom related operational quantities of the International Commission on
[2]
Radiation Units and Measurements (ICRU) . It does not change the concept of ISO 4037.
ISO 4037, focusing on photon reference radiation fields, is divided into four parts. ISO 4037-1 gives the
methods of production and characterization of reference radiation fields in terms of the quantities
photon fluence and air kerma free-in-air. ISO 4037-2 describes the dosimetry of the reference radiation
qualities in terms of air kerma and in terms of the phantom related operational quantities of the
[2]
International Commission on Radiation Units and Measurements (ICRU) . ISO 4037-3 describes the
methods for calibrating and determining the response of dosemeters and doserate meters in terms of
[2]
the operational quantities of the ICRU . This document gives special considerations and additional
requirements for calibration of area and personal dosemeters in low energy X reference radiation fields,
which are reference fields with generating potential lower or equal to 30 kV.
The general procedures described in ISO 29661 including Amendment 1 are used as far as possible in
this document. In addition, the symbols used are in line with ISO 29661.
NOTE For irradiation of the whole body, H (10) and H*(10) are relevant for radiation protection, as long as
p
they are closer to their limit than H′(0,07) and H (0,07). This is the case down to about 15 keV.
p
INTERNATIONAL STANDARD ISO 4037-4:2019(E)
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 4:
Calibration of area and personal dosemeters in low energy
X reference radiation fields
1 Scope
This document gives guidelines on additional aspects of the characterization of low energy photon
radiations and on the procedures for calibration and determination of the response of area and personal
dose(rate)meters as a function of photon energy and angle of incidence. This document concentrates
on the accurate determination of conversion coefficients from air kerma to H (10), H*(10), H (3) and
p p
H'(3) and for the spectra of low energy photon radiations. As an alternative to the use of conversion
coefficients the direct calibration in terms of these quantities by means of appropriate reference
instruments is described.
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 4037-3:2019, 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 3: Calibration
of area and personal dosemeters and the measurement of their response as a function of energy and angle
of incidence
ISO/IEC Guide 98-3:2008, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
me a s ur ement (GUM: 1995)
ISO 29661, Reference radiation fields for radiation protection — Definitions and fundamental concepts
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4037-1, ISO 29661 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
ISO 4037-4:2019(E)
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
low energy X-ray reference radiation
all radiation qualities with nominal tube potentials up to and including 30 kV
Note 1 to entry: These radiation qualities are as specified in ISO 4037-1 and all continuous reference filtered X
radiations.
4 Symbols (and abbreviated terms)
The symbols (and abbreviated terms) used are given in Table 1.
Table 1 — Symbols (and abbreviated terms)
Symbol Meaning Unit
ρ air density kg/m
3 3
ρ air density under reference conditions: ρ = 1,197 4 kg/m kg/m
0 0
ρ air density prevailing during irradiation kg/m
irr
ρ air density prevailing during determination of the conventional quantity value of kg/m
con
the measurand
ρ air density prevailing during calibration of the instrument kg/m
cal
ρ air density prevailing during calibration of the monitor chamber kg/m
MC
ρ air density prevailing during the spectral measurements kg/m
spec
Δρ change of air density kg/m
α angle of radiation incidence to the normal of the phantom surface deg
Δα change of angle of radiation incidence deg
U tube potential V
ΔU change in tube potential V
T air temperature K
T air temperature under reference conditions: T = 293,15 K (equivalent to 20 °C), K
0 0
r relative air humidity —
r relative air humidity under reference conditions: r = 0,65 (equivalent to 65 %) —
0 0
p air pressure kPa
p air pressure under reference conditions: p = 101,3 kPa kPa
0 0
m gradient of the gradient m(d ) m /kg
d air
m(d ) gradient for distance d m /kg
air air
m(1,0 m) gradient for distance 1,0 m m /kg
K air kerma free-in-air Gy
a
k(ρ, M) air density correction factor for measurand M —
H (10) personal dose equivalent at 10 mm depth Sv
p
H (3) personal dose equivalent at 3 mm depth Sv
p
H (0,07) personal dose equivalent at 0,07 mm depth Sv
p
H*(10) ambient dose equivalent at 10 mm depth Sv
H'(3) directional dose equivalent at 3 mm depth Sv
H'(0,07) directional dose equivalent at 0,07 mm depth Sv
h (10; α) conversion coefficient from K to H (10) for angle of radiation incidence α Sv/Gy
pK a p
h* (10) conversion coefficient from K to H*(10) Sv/Gy
p a
h (3; α) conversion coefficient from K to H (3) for angle of radiation incidence α Sv/Gy
pK a p
2 © ISO 2019 – All rights reserved

ISO 4037-4:2019(E)
Table 1 (continued)
Symbol Meaning Unit
E photon energy eV
d distance from the beam exit window of the X-ray tube to the monitor chamber m
MC
d distance from the beam exit window of the X-ray tube to the point of test m
air
–2 –1
Φ (E) spectral fluence at the photon energy E m eV
E
N number of pulses generated in the detector —
Q charge Q generated in the detector by one photon C
2 –1
R(E, Q) response function m C
5 General procedures for calibrating and determining response
In ISO 4037-2, two methods are given to determine the phantom related dose equivalent quantities
for low energy X reference fields. Both methods require a reference field according to ISO 4037-1. The
first method, method I, requires the dosimetry with respect to air kerma free-in-air and after that, the
selected operational quantity is derived by the application of a conversion coefficient that relates the
air kerma free-in-air to the selected operational quantity. For matched reference fields this conversion
coefficient is taken from ISO 4037-3, for characterized reference fields the conversion coefficient
is determined using spectrometry. For the dose-equivalent quantities H'(0,07) and H (0,07), this
p
procedure is associated with only a small additional uncertainty, because the conversion coefficients
depend only slightly on the photon energy and angle of radiation incidence for the ranges given in
ISO 4037-3. Therefore, for these dose equivalent quantities, no special attention is needed for the low
energy X reference radiation fields. For the four other dose equivalent quantities H (10), H*(10), H (3)
p p
and H′(3) this is different. For them, the use of conversion coefficients can be associated with large
additional uncertainties if low energy X reference radiation fields are considered. This is because the
conversion coefficients depend strongly on the photon energy and the angle of radiation incidence.
A detailed description of all the measurements and methods necessary to avoid these additional
[3][4] [5]
uncertainties is given by Ankerhold et al. and by Behrens .
The second method, method II, to determine the phantom related dose quantities is based on the use
of (secondary) standards directly calibrated in terms of these dose equivalent quantities. This method
can also be used for all non-validated radiation qualities, for which the recommended conversion
coefficients cannot be used. This method is described in ISO 4037-2:2019, Clause 6.
If the reference field cannot be validated, then, method I can still be used if a spectrometer is used
to measure the spectrum of the radiation quality under consideration. From this spectrum, the
specific conversion coefficient can be calculated and applied to the measured value of the air kerma K
a
free-in-air.
This document defines the conditions that shall be met to use one of the two methods and the
experimental steps to be used for the selected method. If a monitor chamber (see ISO 4037-2:2019, 9.2)
is used as a transfer device additional corrections shall be applied for differences in the air density
prevailing during calibration of the monitor chamber and during calibration of the instrument under
test. The standard does not give advice on the construction of the instruments necessary for both ways.
[3]
Examples for the instruments and the experimental steps for both ways are given by Ankerhold et al.
[4] [5] [6]
, Behrens and Duftschmid et al. .
6 Characterisation and production of low energy X-ray reference radiations
6.1 General
This subclause specifies the characteristics by which a laboratory can produce the reference filtered
X radiations specified in ISO 4037-1 for the given purposes. For various influence quantities, data are
given on the required stability of these influence quantities. These data indicate how large the change
in value of these influence quantities can be until a change of the measurand of 2 % is caused. These
ISO 4037-4:2019(E)
data shall either be interpreted as limits for the deviation from its nominal value or, where possible, as
a criterion for the necessity of corrections.
The requirements given in ISO 4037-1:2019, 4.2, consider partly the special requirements for low
energy reference radiations for the quantities H (10) or H*(10). These special requirements are, to less
p
extent, also valid for the dose equivalent quantities H′(3), H (3). Therefore, this document focuses on
p
the quantities H (10) or H*(10) and assumes that for the dose equivalent quantities H′(3), H (3) nearly
p p
the same requirements are valid.
6.2 Tube potential
This subclause is relevant for method I and method II. The dose equivalent quantities H (10), H*(10),
p
H (3) and H′(3) are for low energy X radiation more sensitive to the tube potential than the air kerma,
p
K , free-in-air. The requirements on the tube potential given in ISO 4037-1:2019, Table 7 are valid. This
a
Table 7 gives values for the change of tube potential that cause a change in the value of the conversion
coefficient of 2 % if all other parameters are unchanged.
6.3 Spectral fluence and conversion coefficients
This subclause is relevant for method I only. Knowledge of the spectral fluence is necessary to determine
the conversion coefficient from air kerma to the measurand for every radiation quality of the X-ray
facility. In ISO 4037-2:2019, Annex B, an example for the determination of the spectral fluence is given.
The spectral fluence is converted to a spectral air kerma by multiplying the spectral fluence with the
monoenergetic fluence to air kerma conversion coefficients. This spectral air kerma is then multiplied
with the monoenergetic conversion coefficients for the respective measurand (see ISO 4037-3) to
get the spectral H (10), H*(10), H (3) or H'(3) distribution which is then integrated to get the actual
p p
conversion coefficient. The obtained conversion coefficients are valid only for the air density ρ
spec
prevailing during the spectral measurements.
7 Dosimetry of low energy reference radiations
7.1 General
The instruments to be used shall be standard instruments as described in ISO 4037-2:2019, Clause 4.
The general procedures in ISO 4037-2:2019, Clauses 5 and 6, and, where appropriate, the procedures
applicable to ionization chambers in ISO 4037-2:2019, Clause 7, shall be followed.
7.2 Stability check facility
Where appropriate, a radioactive check source may be used to verify the satisfactory operation of the
instrument prior to periods of use.
8 Calibration and determination of the response as a function of photon energy
and angle of radiation incidence
8.1 General
The general methods given in ISO 4037-3 shall be followed. For an unsealed standard ionization chamber
this includes correction for air temperature, pressure and humidity according to ISO 4037-2:2019,
7.4.2. In Cause 8, additional requirements and advice on the selection of calibration method are given.
Moreover, for the dose equivalent quantity H (10) limits are given for the adjustment of the angle of
p
incidence.
4 © ISO 2019 – All rights reserved

ISO 4037-4:2019(E)
8.2 Selection of calibration method
This subclause gives information, additional to ISO 4037-2, on the choice of dosimetric method, which
can be used for determination of the conventional quantity value of the dose quantities of interest. As
explained in Clause 5, two methods are possible to determine the conventional quantity value of the
dose quantities of interest.
For the highest level of dissemination of the phantom related quantities, e.g., by National Metrology
Institutes, Method I, using spectrometry and reference instruments for K is required to achieve an
a
uncertainty of the conventional quantity value of about 6 % (k = 2) or less. The air kerma, K , shall be
a
determined by a primary or at least directly traceable standard and spectrometry of the reference field
shall be performed according to ISO 4037-2:2019, Annex B, both at the point of test.
Method II, using secondary standard instruments, which measure directly dose equivalent quantities,
may be used by all other laboratories. The achievable uncertainty is between 6 % and 10 % (k = 2)
depending on the radiation quality.
The time period starting from the determination of the conventional quantity value of the measurand
until the calibration of the instrument under test and determination of its response as function of
photon energy and angle of radiation incidence has to be considered, because the stability of certain
parameters over this period shall be maintained.
8.3 Calibration by using reference instruments for K
a
8.3.1 General
This subclause is relevant for method I only. During the potentially long time period between the
determination of the conversion coefficient (see 6.3) and the calibration of the instrument the
requirements on tube potential of 6.2 shall be followed. In addition, the air density at all measuring
events shall be constant within the limits given in Table 2, otherwise the appropriate corrections,
provided in Annex A, shall be applied.
The additional corrections for the use of a monitor chamber as a transfer device are also provided in
Annex A.
As an example, Table 2 gives values for the percentage change of air density that causes a change in
the value of the air kerma, K , and the conversion coefficients h (10, 0°), h* (10) and h (10, 60°) of
a pK K pK
2 % at 2,5 m distance of the point of test from the focus and for 0° and 60° radiation incidence. These
conditions are representative for calibrations with respect to H (10) performed on a ISO water slab
p
phantom (see ISO 4037-3).
8.3.2 Conventional quantity value of the air kerma
Within the short time period (typically one or a few hours) from the measurement of the conventional
quantity value of the air kerma and the determination of the required phantom related quantity value
to the calibration of the instrument the air density shall not change by more than the limits given in
Table 2. These data are valid for a distance of 2,5 m, which is typical for calibrations with respect to
H (10) performed on an ISO water slab phantom. Normally, these air density requirements are fulfilled
p
and no correction is necessary, in the other few cases the correction method given in the Annex A shall
be applied as follows. If ρ is the air density prevailing during determination of the conventional
con
quantity value of the air kerma K and ρ those during calibration of the instrument, then the
a cal
conventional quantity value of K during calibration is
a
kKρ ,
()
cala
K ρ = K ρ (1)
() ()
acal acon
kKρ ,
()
cona
For the air density correction factor k(ρ, K ) for the quantity air kerma K see Formula (A.2).
a a
ISO 4037-4:2019(E)
If a monitor chamber is used as a transfer device for the measuring quantity air kerma K then the
a
difference of the air density prevailing during the calibration of the monitor chamber and the air
density prevailing during the calibration of the instrument shall be within the limits given in Table 2.
Otherwise, the correction method given in the Annex A shall be applied as follows. If the monitor
chamber is mounted at a distance d from the beam exit window, ρ is the air density prevailing
MC MC
during calibration of the monitor chamber and ρ those during calibration of the instrument at
cal
the distance d , then the conventional quantity value of K during calibration is (for the air density
air a
correction factor k (ρ, K ) see Formula (A.5)):
MC a
kKρ ,
()
cala
K ρ = K ρ (2)
() ()
acal aMC
kKρ ,
()
MC MC a
Table 2 — Percentage change of air density that causes a change in the value of the air kerma,
K , and the conversion coefficients h (10, 0°) or h* (10) and h (10, 60°) of 2 % at 2,5 m distance
a pK K pK
of the point of test from the focus of the X-ray tube and 0°and 60° radiation incidence
Radiation Tube potential Δρ/ρ for 2,5 m distance causing a change of 2 % of the value of
quality
U K h (10, 0°), h* (10) h (10, 60°)
a pK K pK
kV % % %
L-10 10 0,9 6,3 4,8
L-20 20 5,3 >20 >20
L-30 30 14 >20 >20
N-10 10 0,8 3,5 2,9
N-15 15 2,1 9,2 6,9
N-20 20 4,3 >20 18
N-25 25 8,0 >20 >20
N-30 30 12 >20 >20
H-10 10 0,7 2,4 2,0
H-20 20 1,9 3,7 3,2
H-30 30 4,4 11 9,1
8.3.3 Conventional quantity value of the dose equivalent quantities H (0,07) and H'(0,07)
p
The determination of the conventional quantity value of the dose equivalent quantities H (0,07) and
p
H'(0,07) is based on the determination of the conventional quantity value of the air kerma K plus
a
the application of a conversion coefficient. For matched reference fields the conversion coefficients
given in ISO 4037-3 for the dose equivalent quantities H (0,07) and H'(0,07) shall be applied, while for
p
characterized reference fields the individually determined conversion coefficients shall be used. Using
the conventional quantity value of the air kerma K as determined in 8.3.2, leads to:
a
Hh00,;70ρρ= ,07 K (3)
() () ()
pcal paK cal
′
H' 00,;70ρρ=hK,07 (4)
() () ()
calaK cal
8.3.4 Conventional quantity value of the dose equivalent quantities H (10) or H*(10) and H (3)
p p
or H'(3)
8.3.4.1 Corrections of h (10, α) or h* (10) and h (3, α) or h' (3, α) for air density
pK K pK K
If the air density, ρ , prevailing during calibration of the instrument differs from the air density, ρ ,
cal spec
prevailing during the determination of the conversion coefficient using spectrometry (see 6.3) by more
than the limits given in Table 2, then, in addition to the correction of the air kerma, K , the correction
a
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ISO 4037-4:2019(E)
method given in Annex A shall also be applied to the conversion coefficients h (10, α) or h* (10) and
pK K
h (3, α) or h' (3, α) as follows:
pK K
 
khρα,(10,)
calpK
 
h (,10 αρ,)= h (110,,αρ ) or (5)
pcK al pK spec
 
,α
khρ ,(10 )
 
spec pK
*
 
khρ ,(10)
cal K
*   *
h (,10 ρ )= h (,10 ρ ) and (6)
K cal K speec
 * 
khρ ,(10)
spec K
 
 
khρα,(3,)
calpK
 
h (,3 αρ,)= h (,3 α,,ρ ) or (7)
pcK al pK spec
 
khρ ,(3,α)
 spec pK 
khρα,(′ 3,)
 cal K 
h′ (,3 αρ,)= h′ (,3 α,,ρ ) (8)
K cal K spec
 
h
k ρα,(′K 3,)
 
spec
For the air density correction factors k[ρ, h (10,α)] or k[ρ, h* (10)] and k[ρ, h (3,α)] or k[ρ, h' (3, α)]
pK K pK K
for the conversion coefficients h (10, α) or h* (10) and h (3, α) or h' (3, α), respectively, see A.2.
pK K pK K
8.3.4.2 Evaluation of the effect of angle of radiation incidence α for H (10), H (3) and H'(3)
p p
For a given value of K and parallel radiation incidence the conventional quantity value of the dose
a
equivalent quantities H (10), H (3) and H'(3) is changed if the angle of radiation incidence is changed;
p p
this is not the case for the dose equivalent quantity H*(10). Table 3 gives for unidirectional radiation
fields, as an example, values for the change of the angle of radiation incidence that cause a change in the
value of the dose equivalent quantity H (10) of 2 %. For simplicity, the same values are also assumed for
p
H (3) and H'(3). The angle of radiation incidence shall be within the limits given in Table 3, otherwise
p
the uncertainty shall be determined individually, e.g., by performing special calculations.
NOTE 1 All calculations in 8.3.4.2 are based on the following assumption. For the purpose of calculating
changes of the value of the dose equivalent quantity H (10) for a given radiation quality, the respective conversion
p
coefficient can be replaced by the monoenergetic one for the mean energy.
NOTE 2 The adjustment of the angle of radiation incidence α needs two steps, firstly the adjustment of 0°
incidence and secondly a turn of the device of α. If the uncertainty of the second step is lower than that of the
first step, then two measurements at two angles of radiation incidence of +α and −α are recommended. The mean
value of the two measured values is taken as the value for the angle of radiation incidence α, which compensates
(to the first order) the error of the adjustment of 0° incidence.
ISO 4037-4:2019(E)
Table 3 — Change Δα of the angle of radiation incidence α that causes a change of H (10) of 2 %
p
at 2,5 m distance of the point of test from the focus of the X-ray tube
Δα in degrees causing a change of H (10) of 2 % for angle of inci-
p
Mean energy
Radiation
dence of
quality
keV 0° 15° 30° 45° 60° 75°
−6 a
L-10 9,0 2,0 0,93 0,38 0,17 0,016 (8,8 · 10 )
L-20 17,3 10 4,8 1,9 0,90 0,41 0,083
L-30 26,6 16 10 4,2 1,9 0,83 0,33
−6 a
N-10 8,5 1,8 0,85 0,34 0,15 0,011 (2,7 · 10 )
N-15 12,4 4,4 2,0 0,81 0,40 0,17 0,0078
N-20 16,3 10 4,2 1,7 0,79 0,36 0,066
N-25 20,3 17 7,1 2,6 1,2 0,54 0,15
N-30 24,6 15 9,3 3,7 1,7 0,75 0,28
−6 a
H-10 8,0 1,6 0,80 0,31 0,13 0,0087 (1,2 · 10 )
H-20 13,1 6,4 2,6 1,0 0,52 0,24 0,021
H-30 19,7 17 6,9 2,5 1,2 0,53 0,14
a
Not achievable in practice.
8.3.4.3 Determination of the conventional quantity value of H (10) or H*(10) and H (3) or H'(3)
p p
The determination of the conventional quantity value of the dose equivalent quantities H (10) or H*(10)
p
and H (3) or H'(3) is based on the determination of the conventional quantity value of the air kerma, K ,
p a
plus the application of a conversion coefficient. Using the conventional quantity value of the air kerma,
K , as determined in 8.3.2 leads to:
a
Hh(;10 ρα)(= 10,,ρρ)(K ) or (9)
pcal pcK al acal
*
H*(;10 ρρ)(=hK10,) ()ρ and (10)
calcK al acal
Hh(;33ρα)(= ,,ρρ)(K ) or (11)
pcal pcK al acal
Hh′′(;33ρρ)(= ,,aK)(ρ ) (12)
calcK al acal
Formulae (9) to (12) are used to determine the conversion coefficients.
8.3.5 Performing the calibration
The calibration is done according to ISO 4037-3 using the conventional quantity values determined above.
8.4 Calibration by using reference instruments which measure the ICRU dose
equivalent quantities
8.4.1 General
This subclause is relevant for method II only. Within the time period of typically one hour from the
measurement of the conventional quantity value of the ICRU dose equivalent quantities with the
reference instrument to the calibration of the instrument under test the requirements on tube potential
of 6.2 shall be followed. In addition, the air density shall be stable within the limits given in Table 4,
otherwise the stated corrections, provided in Annex A, shall be applied.
The additional corrections for the use of a monitor chamber as a transfer device are also provided in
Annex A.
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ISO 4037-4:2019(E)
As an example, Table 4 gives values for the percentage change of air density that cause a change in the
value of the dose equivalent quantities H (10, 0°) or H*(10) and H (10, 60°) of 2 % at 2,5 m distance of the
p p
point of test from the focus and for 0° and 60° radiation incidence. These conditions are representative
for calibrations with respect to H (10) performed on a ISO water slab phantom.
p
8.4.2 Conventional quantity value of the dose equivalent quantities H (10) or H*(10) and H (3)
p p
or H'(3)
8.4.2.1 Correction of H (10) or H*(10) and H (3) or H'(3) for air density
p p
Within the short time period (typically one or a few hours) from the measurement of the conventional
quantity value of H (10) or H*(10) and H (3) or H'(3) to the calibration of the instrument the air density
p p
shall not change by more than the limits given in Table 4. For simplicity, the same values are also assumed
for H (3) or H'(3). These data are valid for a distance of 2,5 m, which is typical for calibrations with
p
respect to H (10) performed on an ISO water slab phantom. Normally, these air density requirements
p
are fulfilled and no correction is necessary, in the other few cases the correction method given in the
Annex A shall be applied as follows. If ρ is the air density prevailing during determination of the
con
conventional quantity value of H (10) or H*(10) and H (3) or H'(3) and ρ that during calibration of
p p cal
the instrument, then the conventio
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