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1、 IEC 62494-1 Edition 1.0 2008-08 INTERNATIONAL STANDARD NORME INTERNATIONALE Medical electrical equipment Exposure index of digital X-ray imaging systems Part 1: Definitions and requirements for general radiography Appareils lectromdicaux Indice dexposition des systmes dimagerie numrique rayonnement
2、 X Partie 1: Dfinitions et exigences pour la radiographie gnrale IEC 62494-1:2008 Copyright International Electrotechnical Commission Provided by IHS under license with IECLicensee=Boeing Co/5910770001 Not for Resale, 10/25/2008 03:21:03 MDTNo reproduction or networking permitted without license fro
3、m IHS -,-,- THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2008 IEC, Geneva, Switzerland All rights reserved. Unless otherwise specified, 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
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7、e 3, rue de Varemb CH-1211 Geneva 20 Switzerland Email: inmailiec.ch Web: www.iec.ch About the IEC The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes International Standards for all electrical, electronic and related technologies. About
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17、sitez le FAQ du Service clients ou contactez-nous: Email: csciec.ch Tl.: +41 22 919 02 11 Fax: +41 22 919 03 00 Copyright International Electrotechnical Commission Provided by IHS under license with IECLicensee=Boeing Co/5910770001 Not for Resale, 10/25/2008 03:21:03 MDTNo reproduction or networking
18、 permitted without license from IHS -,-,- IEC 62494-1 Edition 1.0 2008-08 INTERNATIONAL STANDARD NORME INTERNATIONALE Medical electrical equipment Exposure index of digital X-ray imaging systems Part 1: Definitions and requirements for general radiography Appareils lectromdicaux Indice dexposition d
19、es systmes dimagerie numrique rayonnement X Partie 1: Dfinitions et exigences pour la radiographie gnrale INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE R ICS 11.040.50 PRICE CODE CODE PRIX ISBN 2-8318-9944-3 Registered trademark of the International Electrotech
20、nical Commission Marque dpose de la Commission Electrotechnique Internationale Copyright International Electrotechnical Commission Provided by IHS under license with IECLicensee=Boeing Co/5910770001 Not for Resale, 10/25/2008 03:21:03 MDTNo reproduction or networking permitted without license from I
21、HS -,-,- 2 62494-1 IEC:2008 CONTENTS FOREWORD.3 INTRODUCTION.5 1 Scope.7 2 Normative references .7 3 Terms and definitions .7 4 Requirements.9 4.1 Creation of ORIGINAL DATA9 4.2 Determination of the RELEVANT IMAGE REGION and the VALUE OF INTEREST.9 4.3 Requirements for the EXPOSURE INDEX.10 4.4 Cali
22、bration of the EXPOSURE INDEX.10 4.5 Determination of the CALIBRATION FUNCTION.11 4.6 Determination of the INVERSE CALIBRATION FUNCTION11 4.7 Requirements for the DEVIATION INDEX11 Annex A (informative) Details on the rationale, properties and use of the EXPOSURE INDEX13 Annex B (informative) Detail
23、s on the rationale, properties and use of the DEVIATION INDEX17 Annex C (normative) Beam conditions to be used for calibration18 Bibliography19 Terminology Index of defined terms .20 Figure A.1 Example of an ORIGINAL DATA radiograph with an example of the RELEVANT IMAGE REGION outlined .14 Figure A.
24、2 Histogram of the ORIGINAL DATA for the radiograph shown in Figure A.1 15 Figure A.3 Relative IMAGE RECEPTOR AIR KERMA required to produce a fixed detector response for the four x-ray beam qualities defined in ISO 9236-1 .16 Copyright International Electrotechnical Commission Provided by IHS under
25、license with IECLicensee=Boeing Co/5910770001 Not for Resale, 10/25/2008 03:21:03 MDTNo reproduction or networking permitted without license from IHS -,-,- 62494-1 IEC:2008 3 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ MEDICAL ELECTRICAL EQUIPMENT EXPOSURE INDEX OF DIGITAL X-RAY IMAGING SYSTEMS Part
26、 1: Definitions and requirements for general radiography 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-ope
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33、nnot be rendered responsible for any equipment declared to be in conformity with an IEC Publication. 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
34、members of its technical committees and IEC National Committees for any personal injury, property damage or other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and expenses arising out of the publication, use of, or reliance upon, this IEC Publicati
35、on 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) Attention is drawn to the possibility that some of the elements of this IEC Publicati
36、on may be the subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights. International Standard IEC 62494-1 has been prepared by subcommittee 62B: Diagnostic imaging equipment, of IEC technical committee 62: Electrical equipment in medical practice. Th
37、e text of this standard is based on the following documents: Enquiry draft Report on voting 62B/680/CDV 62B/703/RVC 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
38、 the ISO/IEC Directives, Part 2. Copyright International Electrotechnical Commission Provided by IHS under license with IECLicensee=Boeing Co/5910770001 Not for Resale, 10/25/2008 03:21:03 MDTNo reproduction or networking permitted without license from IHS -,-,- 4 62494-1 IEC:2008 In this standard,
39、the following print types are used: requirements, compliance with which can be tested, and definitions: in roman type; explanations, advice, notes, general statements, exceptions and references: in smaller type; TERMS DEFINED IN CLAUSE 3 OF THIS STANDARD, IN IEC 60601-1 OR IN IEC 60788, AS REFERENCE
40、D IN THE INDEX OF DEFINED TERMS: SMALL CAPITALS. A list of all parts of the IEC 62494 series, published under the general title Medical electrical equipment Exposure index of digital X-ray imaging systems, can be found on the IEC website. The committee has decided that the contents of this publicati
41、on will remain unchanged until the maintenance result date indicated on the IEC web site under “http:/webstore.iec.ch“ in the data related to the specific publication. At this date, the publication will be reconfirmed, withdrawn, replaced by a revised edition, or amended. Copyright International Ele
42、ctrotechnical Commission Provided by IHS under license with IECLicensee=Boeing Co/5910770001 Not for Resale, 10/25/2008 03:21:03 MDTNo reproduction or networking permitted without license from IHS -,-,- 62494-1 IEC:2008 5 INTRODUCTION The direct connection between the level of detector exposure and
43、optical density is well established in film-screen radiology. This is not the case in digital radiography, where almost always a constant image characteristic is achieved using automatic image processing. Consequently, deviations from the intended exposure, i.e., over- and underexposure, are not not
44、iceable by a corresponding deviation in image brightness. While considerable underexposure results in an increased level of noise, the more alarming aspect (from a radiation protection point of view) is that overexposure cannot be recognized easily in the displayed image. Therefore, various manufact
45、urers of digital radiography systems have introduced so-called exposure indicators for their equipment. These are numbers, determined from the original image data of each image taken, which allow conclusions about the level of the exposure at the image receptor. However, the exposure indicators are
46、manufacturer or system specific, i.e. they differ for the systems of different manufacturers in their definition and scaling. A unified EXPOSURE INDEX for all digital radiography systems is needed to simplify its usage, e.g. for the establishment of exposure guidelines, particularly when systems of
47、different manufacturers are used within the same department. This standard defines such a concept of the EXPOSURE INDEX. What is laid down here refers to the definition, the scale and the general requirements for the EXPOSURE INDEX. The process of its calculation in detail (software algorithm) is ex
48、cluded from this standard as to not obstruct technical progress. The EXPOSURE INDEX allows the OPERATOR to judge if an image was taken at a detector exposure level suitable for the intended level of image quality. It is important to note that the EXPOSURE INDEX, as defined in this standard, is derived from the image signal, which in turn is usually related to the energy absorbed in the detector, i.e. the detector dose, but not dire