IEC 62220-2-1:2023

IEC 62220-2-1
®

Edition 1.0 2023-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE


Medical electrical equipment – Characteristics of digital X-ray imaging devices –
Part 2-1: Determination of dual-energy subtraction efficiency – Detectors used
for dual-energy radiographic imaging

Appareils électromédicaux – Caractéristiques des dispositifs d’imagerie à
rayonnement X –
Partie 2-1: Détermination de l’efficacité de soustraction à double énergie –
Détecteurs utilisés en imagerie radiographique à double énergie
IEC 62220-2-1:2023-08(en-fr)

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IEC 62220-2-1

®


Edition 1.0 2023-08




INTERNATIONAL



STANDARD




NORME


INTERNATIONALE











Medical electrical equipment – Characteristics of digital X-ray imaging devices –

Part 2-1: Determination of dual-energy subtraction efficiency – Detectors used

for dual-energy radiographic imaging



Appareils électromédicaux – Caractéristiques des dispositifs d’imagerie à

rayonnement X –


Partie 2-1: Détermination de l’efficacité de soustraction à double énergie –

Détecteurs utilisés en imagerie radiographique à double énergie











INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE


INTERNATIONALE





ICS 11.040.50  ISBN 978-2-8322-7305-0




Warning! Make sure that you obtained this publication from an authorized distributor.

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® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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– 2 – IEC 62220-2-1:2023 © IEC 2023
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Requirements . 7
4.1 Operating conditions . 7
4.2 X-RAY EQUIPMENT . 7
4.3 RADIATION QUALITY . 8
4.4 TEST DEVICE . 8
4.5 Geometry . 9
4.6 IRRADIATION conditions . 9
4.6.1 General conditions . 9
4.6.2 IRRADIATION for the determination of the dual-energy contrast . 10
4.6.3 AIR KERMA measurement . 10
5 Corrections of RAW DATA . 10
6 Definitions of the REGIONS OF INTEREST . 11
7 Calculation of derived images . 11
7.1 Calculation of high-energy and low-energy images . 11
7.2 Calculation of TISSUE-SUBTRACTED IMAGES . 12
8 Determination of the dual-energy subtraction efficiency . 13
8.1 Definition and formula of the DSE . 13
8.2 Determination of the dual-energy contrast . 13
9 Format of conformance statement . 14
Annex A (informative) Dual-energy subtraction efficiency interpretation . 15
A.1 Metric description . 15
A.2 Sample device comparisons . 16
Bibliography . 19
Index of defined terms used in this particular standard . 20

Figure 1 – TEST DEVICE for the determination of the dual-energy contrast . 8
Figure 2 – Geometry for all IRRADIATIONS of the TEST DEVICE . 9
Figure 3 – Feature and background REGIONS OF INTEREST defined about circular image
of features . 11
Figure A.1 – Sample DSE results for a simulated MULTI-EXPOSURE DEVICE . 15
s
Figure A.2 – Sample DSE results for a simulated MULTI-EXPOSURE DEVICE at
s
increasing SCINTILLATOR thickness . 17
Figure A.3 – Sample results for a simulated MULTI-EXPOSURE DEVICE at differing
DSE
s
X‑RAY TUBE VOLTAGE used for their high-energy IRRADIATIONS . 17
Figure A.4 – Sample DSE results for a simulated MULTI-EXPOSURE DEVICES at
s
increasing PIXEL pitch . 18

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IEC 62220-2-1:2023 © IEC 2023 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

MEDICAL ELECTRICAL EQUIPMENT –
CHARACTERISTICS OF DIGITAL X-RAY IMAGING DEVICES –

Part 2-1: Determination of dual-energy subtraction efficiency –
Detectors used for dual-energy radiographic imaging

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
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services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
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expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC 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, IEC 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 https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC 62220-2-1 has been prepared by subcommittee 62B: Medical imaging equipment, software,
and systems, of IEC technical committee 62: Medical equipment, software, and systems. It is
an International Standard.
The text of this document is based on the following documents:
Draft Report on voting
62B/1288/CDV 62B/1316/RVC

Full information on the voting for its approval can be found in the report on voting indicated in
the above table.

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– 4 – IEC 62220-2-1:2023 © IEC 2023
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts in the IEC 62220 series, published under the general title Medical electrical
equipment – Characteristics of digital X-ray imaging devices, can be found on the IEC website.
In this document, terms printed in SMALL CAPITALS are used as defined in IEC 60788, in Clause
3 of this document or in other IEC publications referenced in the Index of defined terms. Where
a defined term is used as a qualifier in another defined or undefined term, it is not printed in
SMALL CAPITALS, unless the concept thus qualified is defined or recognized as a “derived term
without definition”.
NOTE Attention is drawn to the fact that, in cases where the concept addressed is not strongly confined to the
definition given in one of the publications listed above, a corresponding term is printed in lower-case letters.
In this document, certain terms that are not printed in SMALL CAPITALS have particular meanings,
as follows:
• "shall" indicates a requirement that is mandatory for compliance;
• "should" indicates a strong recommendation that is not mandatory for compliance;
• "may" indicates a permitted manner of complying with a requirement or of avoiding the need
to comply;
• "specific" is used to indicate definitive information stated in this document or referenced in
other standards, usually concerning particular operating conditions, test arrangements or
values connected with compliance;
• "specified" is used to indicate definitive information stated by the manufacturer in
accompanying documents or in other documentation relating to the equipment under
consideration, usually concerning its intended purposes, or the parameters or conditions
associated with its use or with testing to determine compliance.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

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IEC 62220-2-1:2023 © IEC 2023 – 5 –
INTRODUCTION
Devices that are capable of DUAL-ENERGY IMAGING have been commercially available for over
four decades and are well-known to provide clinical benefits. SINGLE-EXPOSURE DEVICES were
the first to be successfully commercialized in a clinical environment, followed at the beginning
of the century by MULTI-EXPOSURE DEVICES, enabled by the digitalization of X-RAY IMAGE
RECEPTORS. More recently, advances in the field of DUAL-ENERGY IMAGING and a reduction in
component costs have allowed more equipment MANUFACTURERS to enter this market,
supporting a wider clinical adoption and more diverse technological approaches.
Despite this, there is presently no standard metric or associated measurement method to
evaluate the quality of the TISSUE-SUBTRACTED IMAGES – therefore their physical imaging
performance – that different DUAL-ENERGY IMAGING devices produce. This has resulted in a
number of recent challenges for all stakeholders involved, exacerbated by the increasing
diversity in technological approaches.
This document has therefore been developed in order to establish a common, fair, objective,
and reproducible metric and measurement procedures for the evaluation of performance
characteristics of DUAL-ENERGY IMAGING devices.
This document is beneficial to a number of different parties. It enables MANUFACTURERS to better
optimize and compare systems, expediting internal processes and improving final clinical
outcomes. It supports regulatory agencies by providing additional tools to evaluate new DUAL-
ENERGY IMAGING devices. Healthcare institutions gain the ability to interpret results of external
clinical studies and receive a new tool to aid in the development of their own internal protocols.
Lastly, by replacing the current lengthy and costly qualitative nature of TISSUE-SUBTRACTED
IMAGE assessment, it removes a barrier of entry for new companies, thereby increasing market
diversity.
The metrics and methods described in this document evaluate a DUAL-ENERGY IMAGING device
independent of its MANUFACTURER’S TISSUE-SUBTRACTION PROCESSING. This enables a true
analysis of the device’s physical imaging characteristics, without the effects of proprietary
processing algorithms.
Note that, while this document presents metrics that describe the physical imaging performance
of DIGITAL X-RAY IMAGE DEVICES, the connection between these parameters and the decision
performance of a human observer of the TISSUE-SUBTRACTED IMAGES is not yet completely
understood. Furthermore, exhaustive experimental confirmation of the presented metrics has
not yet been carried out, and thus care is taken while interpreting results.

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– 6 – IEC 62220-2-1:2023 © IEC 2023
MEDICAL ELECTRICAL EQUIPMENT –
CHARACTERISTICS OF DIGITAL X-RAY IMAGING DEVICES –

Part 2-1: Determination of dual-energy subtraction efficiency –
Detectors used for dual-energy radiographic imaging



1 Scope
This document describes the performance metrics associated with DUAL-ENERGY IMAGING
capable DIGITAL X-RAY IMAGING DEVICES meant for medical applications and specifies the
methods for their determination. These metrics can be used to analyse TISSUE-SUBTRACTED
IMAGES and to evaluate dose performance, noise characteristics, and tissue-subtraction efficacy
of DIGITAL X-RAY IMAGING DEVICES. The described methods indicate the procedures to obtain
MULTI-SPECTRAL PRIMARY DATA and to compute their derived TISSUE-SUBTRACTED IMAGES.
The intended users of this document are MANUFACTURERS and well-equipped test laboratories.
This document is restricted to DIGITAL X-RAY IMAGING DEVICES that are used for single or multiple
exposure dual-energy radiographic imaging based on, for example, CR systems, direct and
indirect flat panel-detector based systems.
This document excludes and is not applicable to:
– DIGITAL X-RAY IMAGING DEVICES intended to be used in mammography or in dental
RADIOGRAPHY;
– slot scanning DIGITAL X-RAY IMAGING DEVICES;
– COMPUTED TOMOGRAPHY or CONE-BEAM COMPUTED TOMOGRAPHY;
– photon-energy discriminating devices such as photon counting X-RAY IMAGING DEVICES;
– devices for dynamic imaging (where series of images are acquired, as in fluoroscopy or
cardiac imaging).
– DIGITAL X-RAY IMAGING DEVICES intended to be used with RADIOTHERAPY beams.
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.
IEC 60336, Medical electrical equipment – X-ray tube assemblies for medical diagnosis – Focal
spot dimensions and related characteristics
IEC TR 60788:2004, Medical electrical equipment – Glossary of defined terms
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC TR 60788:2004 and
the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:

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IEC 62220-2-1:2023 © IEC 2023 – 7 –
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
DUAL-ENERGY IMAGING
X-ray imaging technique that includes the acquisition of MULTI-SPECTRAL PRIMARY DATA, and the
generation and presentation of one or more corresponding TISSUE-SUBTRACTED IMAGES
3.2
MULTI-SPECTRAL PRIMARY DATA
X-ray data directly derived from RAW DATA of the same object obtained at differing absorbed
X-ray spectra
3.3
TISSUE-SUBTRACTED IMAGE
image obtained through TISSUE-SUBTRACTION PROCESSING with the purpose of removing contrast
in tissues or structures not relevant to the intended imaging task
3.4
TISSUE-SUBTRACTION PROCESSING
processing of MULTI-SPECTRAL PRIMARY DATA – typically dual-energy logarithmic subtraction –
with the goal of removing contrast between structures of similar spectral X-ray ABSORPTION
characteristics
3.5
SINGLE-EXPOSURE DEVICE
DIGITAL X-RAY IMAGING DEVICE that achieves the acquisition of MULTI-SPECTRAL PRIMARY DATA with
a single IRRADIATION
3.6
MULTI-EXPOSURE DEVICE
DIGITAL X-RAY IMAGING DEVICE that achieves the acquisition of MULTI-SPECTRAL PRIMARY data
through multiple IRRADIATIONS obtained at different times and using various X-RAY TUBE VOLTAGE
and/or ADDITIONAL FILTRATION
3.7
MULTI-EXPOSURE MOTION ARTIFACT
image ARTIFACT present in TISSUE-SUBTRACTED IMAGE that result from object misalignment
between the image in the MULTI-SPECTRAL PRIMARY DATA, seen in MULTI-EXPOSURE DEVICES
caused by patient motion between IRRADIATIONS
4 Requirements
4.1 Operating conditions
The DIGITAL X-RAY IMAGING DEVICE shall be operated according to the MANUFACTURER’S
recommendations. The warm-up time shall be chosen according to the recommendations of the
MANUFACTURER. The operating conditions shall be the same as those intended for clinical use
and shall be maintained during all IRRADIATIONS required for these tests. When multiple clinical
use recommendations exist, those that are recommended by the MANUFACTURER for DUAL-
ENERGY IMAGING of the chest shall be selected.
4.2 X-RAY EQUIPMENT
For all tests described in the following subclauses, a CONSTANT POTENTIAL HIGH-VOLTAGE
GENERATOR is recommended (IEC 60601-2-54). The PERCENTAGE RIPPLE shall be no larger than
4.

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– 8 – IEC 62220-2-1:2023 © IEC 2023
The NOMINAL FOCAL SPOT VALUE (IEC 60336) shall be no larger than 1,2.
For the measuring of AIR KERMA, calibrated RADIATION METERS shall be used. The uncertainty
(coverage factor 2) of the measurements shall be less than 5 %.
4.3 RADIATION QUALITY
The RADIATION QUALITIES selected for each IRRADIATION shall use a fixed X-RAY TUBE VOLTAGE,
an ADDITIONAL FILTRATION material and an ADDITIONAL FILTRATION material thickness that match
those recommended by the MANUFACTURER for clinical applications of DUAL-ENERGY IMAGING of
MULTI-EXPOSURE DEVICE is being used, a different value of each of these
the chest. If a
parameters can be selected for each IRRADIATION.
4.4 TEST DEVICE
The TEST DEVICE for the determination of the dual-energy contrast shall consist of alternating
layers of acrylic (polymethyl methacrylate) and aluminum plates. Each layer shall be a solid
square cuboid slab of material, arranged in the configuration described in Figure 1. The
dimensions of each of these slabs, as labelled in Figure 1, shall be a= 300 mm , b≤150 mm ,
c= 9,5 mm , d= 2,5 mm , e=‍54 mm , f=1,6 mm , g=190 mm . The purity of the
constituent aluminum shall be at least 98 % and the density of the acrylic used shall be
3
1,19± 0, 02 g / cm .
A feature insert shall be placed on top of the second aluminum layer and provides the necessary
material contrast for the calculation of the metric. This insert shall contain ten cylindrical
protrusions of either acrylic or aluminum. Each material feature shall be numbered 1 through 5
and be of uniformly increasing thickness. Their relative arrangement in the insert shall follow
that shown in Figure 1. Each cylinder shall be 25 mm in diameter and be separated from all
other features by at least 11 mm from any point in either feature’s perimeter. The thicknesses
of aluminum features shall be, in increasing label order, 0,5 mm, 1,0 mm, 1,5 mm, 2,0 mm, and
2,5 mm. The thickness of the acrylic features shall be, in increasing label order, 2 mm, 4 mm,
6 mm, 8 mm, and 10 mm.

A side view of the TEST DEVICE (left) and a top view of the feature insert (right) are shown. The TEST DEVICE shall
consist of alternating square cuboid layer of acrylic (light grey) and aluminum (dark grey). Note the air gap between
some central layers of the device. The feature insert shall contain cylindrical features of either material, labelled 1
through 5 for each material.
Figure 1 – TEST DEVICE for the determination of the dual-energy contrast

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IEC 62220-2-1:2023 © IEC 2023 – 9 –
4.5 Geometry
The geometrical set-up of all X-RAY EQUIPMENT and of the TEST DEVICE shall comply with Figure 2
for all IRRADIATIONS. The TEST DEVICE shall be placed as close as possible and parallel to the
DETECTOR SURFACE. Other X-RAY EQUIPMENT can be present between the TEST DEVICE and the
DETECTOR SURFACE, such as ANTI-SCATTER GRIDS or AUTOMATIC EXPOSURE CONTROL sensors. Any
X-RAY EQUIPMENT present during IRRADIATIONS (such as a VERTICAL EXAMINATION STAND, ANTI-
SCATTER GRID, or AUTOMATIC EXPOSURE CONTROL sensor) that does not comply with or is not
MANUFACTURER for clinical
included in Figure 2 can be used only if it is recommended by the
use.
The distance between the FOCAL SPOT of the X-RAY TUBE and the DETECTOR SURFACE, ℎ, shall be
no less than 150 cm. If, for technical reasons, this distance requirement cannot be met, a
smaller distance can be chosen and shall be explicitly declared when reporting results. The
REFERENCE AXIS shall be aligned with the CENTRAL AXIS.

Figure 2 – Geometry for all IRRADIATIONS of the TEST DEVICE
4.6 IRRADIATION conditions
4.6.1 General conditions
Calibration of the DIGITAL X-RAY IMAGING DEVICE shall be carried out prior to any testing as
specified by the MANUFACTURER. The measurements specified in this document shall be
ex
...