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    IEC TR 62799-2013 Models for evaluation of thermal hazard in medical diagnostic ultrasound fields《医用诊断超声波场中热危害的评价模型》.pdf

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    IEC TR 62799-2013 Models for evaluation of thermal hazard in medical diagnostic ultrasound fields《医用诊断超声波场中热危害的评价模型》.pdf

    1、 IEC/TR 62799 Edition 1.0 2013-09 TECHNICAL REPORT Models for evaluation of thermal hazard in medical diagnostic ultrasonic fields IEC/TR 62799:2013(E) THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2013 IEC, Geneva, Switzerland All rights reserved. Unless otherwise specified, no part of this pub

    2、lication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either IEC or IECs member National Committee in the country of the requester. If you have any questions about IEC copyright or have a

    3、n enquiry about obtaining additional rights to this publication, please contact the address below or your local IEC member National Committee for further information. IEC Central Office Tel.: +41 22 919 02 11 3, rue de Varemb Fax: +41 22 919 03 00 CH-1211 Geneva 20 infoiec.ch Switzerland www.iec.ch

    4、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 IEC publications The technical content of IEC publications is kept under constant re

    5、view by the IEC. Please make sure that you have the latest edition, a corrigenda or an amendment might have been published. Useful links: IEC publications search - www.iec.ch/searchpub The advanced search enables you to find IEC publications by a variety of criteria (reference number, text, technica

    6、l committee,). It also gives information on projects, replaced and withdrawn publications. IEC Just Published - webstore.iec.ch/justpublished Stay up to date on all new IEC publications. Just Published details all new publications released. Available on-line and also once a month by email. Electrope

    7、dia - www.electropedia.org The worlds leading online dictionary of electronic and electrical terms containing more than 30 000 terms and definitions in English and French, with equivalent terms in additional languages. Also known as the International Electrotechnical Vocabulary (IEV) on-line. Custom

    8、er Service Centre - webstore.iec.ch/csc If you wish to give us your feedback on this publication or need further assistance, please contact the Customer Service Centre: csciec.ch. IEC/TR 62799 Edition 1.0 2013-09 TECHNICAL REPORT Models for evaluation of thermal hazard in medical diagnostic ultrason

    9、ic fields INTERNATIONAL ELECTROTECHNICAL COMMISSION X ICS 11.040.50 PRICE CODE ISBN 978-2-8322-1099-4 Registered trademark of the International Electrotechnical Commission Warning! Make sure that you obtained this publication from an authorized distributor. 2 TR 62799 IEC:2013(E) CONTENTS FOREWORD .

    10、 4 1 Scope 6 2 Normative references 6 3 Terms and definitions 6 4 Background . 10 4.1 General 10 4.2 Limitations of the existing standard 11 4.2.1 Linear display . 11 4.2.2 Equilibrium temperature 12 4.2.3 Tissue parameters 12 4.2.4 Transducer self-heating 12 4.2.5 Safety limits 12 5 Options for imp

    11、rovement of the existing standard 13 5.1 General 13 5.2 Exponential display of the current TI 13 5.2.1 Theory 13 5.2.2 Illustrative results for the new thermal index display . 15 5.2.3 Advantages of the new display . 15 5.2.4 Shortcomings of the new display . 16 5.3 Replacement of the TI with the th

    12、ermally equivalent time index (TETI) . 16 5.3.1 Theory 16 5.3.2 Illustrative results for the TETI 20 5.3.3 Advantages of the TETI. 22 5.3.4 Shortcomings of the TETI 22 5.4 Replacement of the TI with the time to threshold (TT). 23 5.4.1 Theory 23 5.4.2 Illustrative results for the TT 24 5.4.3 Advanta

    13、ges of the TT 27 5.4.4 Shortcomings of the TT . 27 5.5 Replacement of the TI with the safe use time (SUT) . 28 5.5.1 Theory 28 5.5.2 Illustrative results for the SUT . 30 5.5.3 Advantages of the SUT 33 5.5.4 Shortcomings of the SUT . 33 5.6 Replacement of the TI with the thermally equivalent time di

    14、splayed (TETD) . 34 5.6.1 Theory 34 5.6.2 Illustrative results for the TETD . 35 5.6.3 Advantages of the TETD . 38 5.6.4 Shortcomings of the TETD 39 6 Summary . 40 7 Recommendations . 41 7.1 General 41 7.2 Thermally equivalent time index . 41 7.3 Other models . 41 Bibliography 42 TR 62799 IEC:2013(E

    15、) 3 Figure 1 Comparison of the values of thermal index that would be displayed under the proposed definition, TI new , with that displayed currently, TI cur. 15 Figure 2 Expanded view of the comparison of Figure 1 for smaller values of TI cur15 Figure 3 Thermal-equivalent core temperature elevations

    16、 vs time 18 Figure 4 Temperature-time curve (solid line) that represents a conservative boundary for non-foetal exposure durations, particularly for exposure durations of less than 5 s 19 Figure 5 Thermally equivalent time index (solid curves) vs foetal exposure duration for TI = 1, 2, 3 and 4 . 21

    17、Figure 6 Temperature rise for distance (z 0 3 cm) for four models as a function of US exposure time . 25 Figure 7 Relation between TT (time to threshold) and power parameters that give a temperature rise of T thr= 4 C 26 Figure 8 The ratio of temperature rise to acoustic absorption coefficient, T/,

    18、vs exposure duration for the non-scanning soft tissue model with P a= 100 mW. . 27 Figure 9 A typical example of temperature rise due to diagnostic ultrasound 29 Figure 10 Values of temperature rise as a function of insonation time 31 Figure 11 The thermal load as a function of time and f-number 32

    19、Figure 12 A comparison of thermally equivalent times (t 43 ) for the temperature profiles shown in Figure 6 . 36 Figure 13 Probability of birth defect or kidney necrosis as a function of thermally equivalent time (t 43 ) . 37 Figure 14 Probabilities of kidney necrosis estimated for the thermally equ

    20、ivalent times (t 43 ) shown in Figure 12 38 Figure 15 Probabilities of birth defect estimated for the thermally equivalent times (t 43 ) shown in Figure 12 . 39 Table 1 Thermally equivalent time thresholds for chronic damage in various tissues, t 43 ; see 21. 20 Table 2 Foetal exposure durations for

    21、 a thermally equivalent time index value of 1 22 Table 3 Non-foetal exposure durations for a thermally equivalent time index value of 1 . 22 Table 4 SUT values when including and ignoring the contribution of temperatures lower than T maxfor the four exposure conditions and the corresponding values o

    22、f T max32 Table 5 Values of W, W a , and T maxfor the case of SUT = 500 s. . 33 Table 6 Comparison of significant characteristics of the possible replacements for the TI. . 40 4 TR 62799 IEC:2013(E) INTERNATIONAL ELECTROTECHNICAL COMMISSION _ MODELS FOR EVALUATION OF THERMAL HAZARD IN MEDICAL DIAGNO

    23、STIC ULTRASONIC FIELDS 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

    24、 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 pre

    25、paration 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 closel

    26、y 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

    27、 subjects since each technical committee has representation from all interested IEC National Committees. 3) IEC Publications have the form of recommendations for international use and are accepted by IEC National Committees in that sense. While all reasonable efforts are made to ensure that the tech

    28、nical content of IEC Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any misinterpretation by any end user. 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications transparently to the maximum ext

    29、ent possible in their national and regional publications. Any divergence between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter. 5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide

    30、 conformity assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any 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

    31、 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 other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and expenses a

    32、rising 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) Attention

    33、is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights. The main task of IEC technical committees is to prepare International Standards. However, a technical co

    34、mmittee may propose the publication of a technical report when it has collected data of a different kind from that which is normally published as an International Standard, for example “state of the art“. IEC 62799, which is a technical report, has been prepared by IEC technical committee 87: Ultras

    35、onics. The text of this technical report is based on the following documents: Enquiry draft Report on voting 87/510/DTR 87/537/RVC Full information on the voting for the approval of this technical report can be found in the report on voting indicated in the above table. This publication has been dra

    36、fted in accordance with the ISO/IEC Directives, Part 2. TR 62799 IEC:2013(E) 5 Terms appearing in bold print in the text are defined in Clause 3 of this technical report. The committee has decided that the contents of this publication will remain unchanged until the stability date indicated on the I

    37、EC 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. A bilingual version of this publication may be issued at a later date. 6 TR 62799 IEC:2013(E) MODELS FOR

    38、 EVALUATION OF THERMAL HAZARD IN MEDICAL DIAGNOSTIC ULTRASONIC FIELDS 1 Scope This technical report provides background information for users of IEC 62359 to understand the relative merits of several of the potential replacements for the thermal index (TI) as described in IEC 60601-2-37 and IEC 6235

    39、9. The report discusses: parameters related to thermal aspects of diagnostic ultrasonic fields; methods for the determination of an exposure parameter relating to temperature rise in theoretical tissue-equivalent models, resulting from absorption of ultrasound. The report is intended to be used by:

    40、those involved in the development and maintenance of IEC 62359; manufacturers of medical electrical equipment for risk assessment; health care regulatory authorities, test houses and other organizations responsible for implementing standards for medical electrical equipment. 2 Normative references T

    41、he following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 6060

    42、1-2-37:2007, Medical electrical equipment Part 2-37: Particular requirements for the basic safety and essential performance of ultrasonic medical diagnostic and monitoring equipment IEC 62127-1:2007, Ultrasonics Hydrophones Part 1: Measurement and characterization of medical ultrasonic fields up to

    43、40 MHz IEC 62127-2, Ultrasonics Hydrophones Part 2: Calibration for ultrasonic fields up to 40 MHz IEC 62359:2010, Ultrasonics Field characterization Test methods for the determination of thermal and mechanical indices related to medical diagnostic ultrasonic fields 3 Terms and definitions For the p

    44、urposes of this technical report, the terms and definitions given in IEC 60601-2-37, IEC 62127-1, IEC 62127-2 and IEC 62359, some of which are repeated below for convenience, and the following terms and definitions apply. 3.1 acoustic absorption coefficient quantity intended to account for loss of u

    45、ltrasonic energy to tissue at a specified point by mechanisms other than scattering TR 62799 IEC:2013(E) 7 Note 1 to entry: Acoustic absorption coefficient is expressed in nepers per centimetre (Np cm -1 ). Note 2 to entry: The acoustic absorption coefficient must be less than or equal to the acoust

    46、ic attenuation coefficient. 3.2 acoustic attenuation coefficient quantity intended to account for reduction of energy of an acoustic wave by all mechanisms involving interaction of the wave and all matter between the source and a specified point Note 1 to entry: Acoustic attenuation coefficient is e

    47、xpressed in nepers per centimetre (Np cm -1 ). Note 2 to entry: The acoustic attenuation coefficient must be greater than or equal to the acoustic absorption coefficient. Note 3 to entry: The acoustic attenuation coefficient does not account for geometric attenuation. 3.3 acoustic working frequency

    48、f awffrequency of an acoustic signal based on the observation of the output of a hydrophone placed in an acoustic field at the position corresponding to the spatial-peak temporal-peak acoustic pressure Note 1 to entry: The signal is analysed using either the zero-crossing acoustic-working frequency

    49、technique or a spectrum analysis technique. Acoustic working frequencies are defined in 3.3.1 and 3.3.2. Note 2 to entry: In a number of cases the present definition is not very helpful or convenient, especially for broadband transducers. In that case a full description of the frequency spectrum should be given in order to enable any frequency-dependent correction to the signal. Note 3 to entry: Acoustic working frequency is expressed in hertz (Hz)


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