IEC 62220-1:2003
(Main)Medical electrical equipment - Characteristics of digital X-ray imaging devices - Part 1: Determination of the detective quantum efficiency
Medical electrical equipment - Characteristics of digital X-ray imaging devices - Part 1: Determination of the detective quantum efficiency
Specifies the method for the determination of the detective quantum efficiency (DQE) of digital X-ray imaging devices as a function of exposure and of spatial frequency for the working conditions in the range of the medical application as specified by the manufacturer. Is applicable to projection digital X-ray imaging devices producing images in digital format that are used for medical diagnosis. It is restricted to digital X-ray imaging devices that are used for radiographic imaging, such as CR systems, selenium-based systems, flat panel detectors, optically coupled CCD detectors, and digital X-ray image intensifiers used for single exposures.
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INTERNATIONAL IEC
STANDARD
62220-1
First edition
2003-10
Medical electrical equipment –
Characteristics of digital X-ray imaging devices –
Part 1: Determination of the detective quantum
efficiency
Appareils électromédicaux –
Caractéristiques des appareils d'imagerie à rayonnement X –
Partie 1: Détermination de l'efficacité quantique de détection
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INTERNATIONAL IEC
STANDARD
62220-1
First edition
2003-10
Medical electrical equipment –
Characteristics of digital X-ray imaging devices –
Part 1: Determination of the detective quantum
efficiency
Appareils électromédicaux –
Caractéristiques des appareils d'imagerie à rayonnement X –
Partie 1: Détermination de l'efficacité quantique de détection
IEC 2003 Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or
mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
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International Electrotechnical Commission
Международная Электротехническая Комиссия
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– 2 – 62220-1 IEC:2003(E)
CONTENTS
FOREWORD . 3
INTRODUCTION .5
1 Scope . 6
2 Normative references. 6
3 Terminology and definitions . 7
4 Requirements . 8
4.1 Operating conditions. 8
4.2 X-RAY EQUIPMENT . 8
4.3 RADIATION QUALITY . 9
4.4 TEST DEVICE .10
4.5 Geometry.11
4.6 IRRADIATION conditions.13
4.6.1 General conditions.13
4.6.2 Exposure measurement .13
4.6.3 Avoidance of LAG EFFECTS .14
4.6.4 IRRADIATION to obtain the CONVERSION FUNCTION.14
4.6.5 IRRADIATION for determination of the NOISE POWER SPECTRUM .14
4.6.6 IRRADIATION with TEST DEVICE in the RADIATION BEAM .15
5 Corrections of RAW DATA .16
6 Determination of the DETECTIVE QUANTUM EFFICIENCY.16
6.1 Definition and formula of DQE(u,v) .16
6.2 Parameters to be used for evaluation .17
6.3 Determination of different parameters from the images .17
6.3.1 Linearization of data .17
6.3.2 The NOISE POWER SPECTRUM (NPS).18
6.3.3 Determination of the MODULATION TRANSFER FUNCTION (MTF).20
7 Format of conformance statement.20
8 Accuracy.21
Annex A (normative) Determination of LAG EFFECTS .23
A.1 Test of additive LAG EFFECTS .23
A.2 Test of multiplicative LAG EFFECTS.24
Annex B (normative) Terminology – Index of defined terms.26
Annex C (informative) Calculation of the input NOISE POWER SPECTRUM.27
Bibliography.28
62220-1 IEC:2003(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MEDICAL ELECTRICAL EQUIPMENT –
CHARACTERISTICS OF DIGITAL X-RAY IMAGING DEVICES –
Part 1: Determination of the detective quantum efficiency
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62220-1 has been prepared by subcommittee 62B: Diagnostic
imaging equipment, of IEC technical committee 62: Electrical equipment in medical practice.
The text of this standard is based on the following documents:
FDIS Report on voting
62B/493/FDIS 62B/506/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
– 4 – 62220-1 IEC:2003(E)
In this standard, terms printed in SMALL CAPITALS are used as defined in IEC 60788, in
Clause 3 of this standard or other IEC publications referenced in Annex B. 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.
The committee has decided that the contents of this publication will remain unchanged until
2006-12. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
62220-1 IEC:2003(E) – 5 –
INTRODUCTION
DIGITAL X-RAY IMAGING DEVICES are increasingly used in medical diagnosis and will widely
replace conventional (analogue) imaging devices such as screen-film systems or analogue X-
RAY IMAGE INTENSIFIER television systems in the future. It is necessary, therefore, to define
parameters that describe the specific imaging properties of these DIGITAL X-RAY IMAGING
DEVICES and to standardize the measurement procedures employed.
There is growing consensus in the scientific world that the DETECTIVE QUANTUM EFFICIENCY
(DQE) is the most suitable parameter for describing the imaging performance of an X-ray
imaging device. The DQE describes the ability of the imaging device to preserve the signal-to-
NOISE ratio from the radiation field to the resulting digital image data. Since in X-ray imaging,
the NOISE in the radiation field is intimately coupled to the exposure level, DQE values can
also be considered to describe the dose efficiency of a given imaging device.
NOTE 1 In spite of the fact that the DQE is widely used to describe the performance of imaging devices, the
connection between this physical parameter and the decision performance of a human observer is not yet
1)
completely understood [1], [3].
NOTE 2 The standard IEC 61262-5 specifies a method to determine the DQE of X-RAY IMAGE INTENSIFIERS at
nearly zero SPATIAL FREQUENCY. It focuses only on the electro-optical components of X-RAY IMAGE INTENSIFIERS, not
on the imaging properties as this standard does. As a consequence, the output is measured as an optical quantity
(luminance), and not as digital data. Moreover, IEC 61262-5 prescribes the use of a RADIATION SOURCE ASSEMBLY,
whereas this standard prescribes the use of an X-RAY TUBE. The scope of IEC 61262-5 is limited to X-RAY IMAGE
INTENSIFIERS and does not interfere with the scope of this standard.
The DQE is already widely used by manufacturers to describe the performance of their
equipment. The specification of the DQE is also required by regulatory agencies (such as the
Food and Drug Administration (FDA)) for admission procedures. However, there is presently
no standard governing either the measurement conditions or the measurement procedure with
the consequence that values from different sources may not be comparable.
This standard has therefore been developed in order to specify the measurement procedure
together with the format of the conformance statement for the DETECTIVE QUANTUM EFFICIENCY
of DIGITAL X-RAY IMAGING DEVICES.
In the DQE calculations proposed in this standard, it is assumed that system response is
measured for objects that attenuate all energies equally (task-independent) [5].
The standard will be beneficial for manufacturers, users, distributors and regulator
...
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