IEC 61685-2001 Ultrasonics - Flow measurement systems - Flow test object《超声学 流量测量系统 流量试验物》.pdf

1、INTERNATIONAL STANDARD IEC 61685 First edition 2001-07 Ultrasonics Flow measurement systems Flow test object Ultrasons Systmes de mesure de dbit Montage pour essai de dbit Reference number IEC 61685:2001(E)Publication numbering As from 1 January 1997 all IEC publications are issued with a designatio

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7、) for further information. Customer Service Centre If you have any questions regarding this publication or need further assistance, please contact the Customer Service Centre: Email: custserviec.ch Tel: +41 22 919 02 11 Fax: +41 22 919 03 00INTERNATIONAL STANDARD IEC 61685 First edition 2001-07 Ultr

8、asonics Flow measurement systems Flow test object Ultrasons Systmes de mesure de dbit Montage pour essai de dbit PRICE CODE IEC 2001 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

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10、ernational Electrotechnical Commission 2 61685 IEC:2001(E) CONTENTS FOREWORD 4 INTRODUCTION 5 1 Scope 6 2 Normative references. 6 3 Definitions 6 4 List of symbols . 11 5 General outline of flow Doppler test object 12 6 Specification of the flow Doppler test object 12 6.1 General. 12 6.2 Blood-mimic

11、king fluid (BMF) 13 6.3 Tube. 14 6.4 Tissue-mimicking material (TMM) 15 6.5 Geometry 15 7 Precautions to prevent changes in the composition of the blood-mimicking fluid (BMF) 15 8 Specifications for labelling 16 Annex A (informative) Rationale concerning the position of this standard 17 Annex B (nor

12、mative) Formulae relating various quantities 20 Annex C (informative) Rationale for the numerical values chosen in this standard 21 Annex D (informative) Description of an example flow Doppler test object 23 Annex E (informative) Schematic diagram of a possible flow circuit 32 Annex F (informative)

13、Measuring methods . 33 Bibliography . 34 Figure 1 Three configurations for Doppler flow test objects. 12 Figure D.1 The main elements of a flow test object 24 Figure D.2 Backscattering coefficient of BMF as a function of frequency 26 Figure D.3 Attenuation of TMM ( ) and BMF ( ) as a function of fre

14、quency 26 Figure D.4 Attenuation of ultrasound by material of tube wall, as a function of frequency . 27 Figure D.5 Deformation of velocity spectrum of parabolic flow by attenuation due to tube wall (wall thickness 1,5 mm) 28 Figure D.6 Backscattering coefficient of two samples of TMM as a function

15、of frequency . 29 Figure D.7 The quotient of attenuation by TMM (1-way passage) and frequency as a function of frequency 29 Figure D.8 Testing for penetration depth 31 Figure E.1 Schematic diagram of a possible flow circuit, showing the place of the flow Doppler test object . 3261685 IEC:2001(E) 3 T

16、able 1 Typical ranges of parameters for blood at 37 C, where f is the acoustic- working frequency in hertz 13 Table 2 Specification of blood-mimicking fluid (BMF) 13 Table 3 Parameters of tissue-mimicking material (TMM) 15 Table A.1 Parameters concerning CW Doppler 18 Table A.2 Additional parameters

17、 concerning pulsed Doppler and colour flow 19 4 61685 IEC:2001(E)INTERNATIONAL ELECTROTECHNICAL COMMISSION _ ULTRASONICS FLOW MEASUREMENT SYSTEMS FLOW TEST OBJECT FOREWORD 1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising all national e

18、lectrotechnical committees (IEC National Committees). The object of the 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, the IEC publishes International Standards. Their

19、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. The IEC collaborates

20、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 the IEC on technical matters express, as nearly as possible, an international consensus of opinion on th

21、e relevant subjects since each technical committee has representation from all interested National Committees. 3) The documents produced have the form of recommendations for international use and are published in the form of standards, technical specifications, technical reports or guides and they a

22、re accepted by the National Committees in that sense. 4) In order to promote international unification, IEC National Committees undertake to apply IEC International Standards transparently to the maximum extent possible in their national and regional standards. Any divergence between the IEC Standar

23、d and the corresponding national or regional standard shall be clearly indicated in the latter. 5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any equipment declared to be in conformity with one of its standards. 6) Attention is drawn to the

24、possibility that some of the elements of this International Standard may be the subject of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights. International Standard IEC 61685 has been prepared by IEC Technical Committee 87: Ultrasonics. The text of th

25、is standard is based on the following documents: FDIS Report on voting 87/202/FDIS 87/208/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 Directive

26、s, Part 3. Annexes A, C, D, E and F are for information only. Annex B forms an integral part of this standard. The committee has decided that the contents of this publication will remain unchanged until 2006. At this date, the publication will be reconfirmed; withdrawn; replaced by a revised edition

27、 or amended.61685 IEC:2001(E) 5 INTRODUCTION The purpose of this International Standard is to establish a flow Doppler test object for the acceptance testing, quality assurance testing and clinical calibration of Doppler systems, working at a frequency between 2 MHz and 10 MHz. As the response of D

28、oppler systems depends on the signal level and on the spectral contents of the signal, it is desirable to test some aspects of a Doppler system with a test object that mimics the in vivo situation. A flow Doppler test object is particularly useful for testing the influence of the size and the depth

29、of the blood vessel on the signal recorded by a Doppler system; testing the response of a Doppler system with a spectrum of blood velocities typical of the in vivo situation. This flow test object is not intended as a phantom mimicking clinical conditions. The basis of this International Standard is

30、 given by IEC Technical Report 61206:1993 Ultrasonics Continuous Wave Doppler systems Test procedures. In annex A the position of this standard in relation to IEC 61206 and IEC 61895 is described. This standard only declares parameters that can be measured with the test object. Measurement methods a

31、re given in IEC 61206 and IEC 61895. This International Standard deals only with the flow Doppler test object in a restricted sense, i.e. the section in which the ultrasonic measurements are performed. Where the whole of the set-up is meant, the phrase flow rig is used. The prescriptions of this Int

32、ernational Standard define the ultrasonic properties and the flow pattern in the measurement section of the flow test object. For other aspects of the flow rig (i.e. generating and measuring flows) standard engineering practice has to be followed. The flow conditions are simplified as much as possib

33、le: a steady flow through a straight tube with a circular cross-section. Generalisation of the flow conditions to other geometries and time dependent flows is required in order to test some instrument functions. This generalisation is not undertaken in this International Standard. In annex D, an exa

34、mple flow Doppler test object is described which complies with the requirements of this International Standard. Compliance with this International Standard can also be fulfilled by measuring the properties of the materials to be used, and complying with the values given in this International Standar

35、d. In literature 1, 2 the nomenclature about the primary measurand of Doppler systems is confused. Doppler frequency and velocity occur on equal footing. In velocity often a correction for Doppler angle has been included. To avoid this ambiguity, in this International Standard the term Doppler frequ

36、ency is preferred. In case a Doppler system is declared to measure velocity, it is intended that measured values are converted to Doppler frequency, using acoustic working frequency and, if applicable, Doppler angle. 6 61685 IEC:2001(E) ULTRASONICS FLOW MEASUREMENT SYSTEMS FLOW TEST OBJECT 1 Scope T

37、his International Standard specifies parameters for a flow Doppler test object representing a blood vessel of known diameter at a certain depth in human tissue, carrying a steady flow. This International Standard establishes a flow Doppler test object which can be used to assess various aspects of t

38、he performance of Doppler diagnostic equipment. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publi

39、cations do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to ap

40、plies. Members of IEC and ISO maintain registers of currently valid International Standards. IEC 61206:1993, Ultrasonics Continuous-wave Doppler systems Test procedures IEC 61102:1991, Measurement and characterisation of ultrasonic fields using hydrophones in the frequency range 0,5 MHz to 15 MHz IE

41、C 61895:1999, Ultrasonics Pulsed Doppler diagnostic systems Test procedures to determine performance 3 Definitions For the purposes of this International Standard, the following definitions apply: 3.1 3 dB Doppler frequency frequency at which the power per unit frequency in the Doppler spectrum is h

42、alf (3 dB) of the maximum value 3.2 3 dB sample volume volume of a region in space for which the Doppler system gives a response to a point Doppler target that is above 3 dB from the maximal response, taking account of the effects of both transmission and reception Unit: cubic millimetre, mm 3 3.3 3

43、 dB sample volume length largest dimension of the 3 dB sample volume in the direction of the beam alignment axis (see 3.5 of IEC 61102) Unit: millimetre, mm61685 IEC:2001(E) 7 3.4 3 dB sample volume width largest value of the dimension of the 3 dB sample volume along an axis which is perpendicular t

44、o the beam alignment axis. In case the Doppler system has a scan plane, the axes are taken in the scan plane and perpendicular to the scan plane Unit: millimetre, mm 3.5 acoustic-working frequency frequency of an acoustic signal based on the output observed by a hydrophone placed in an acoustic fiel

45、d: it is the arithmetic mean of the two frequencies at which the amplitude of the acoustic pressure spectrum is 3 dB below the peak amplitude conforms to 3.4.2 of IEC 61102 Unit: hertz, Hz 3.6 aliasing false indication of signal frequency as a result of sampling at too low a frequency NOTE The thres

46、hold for aliasing depends on pulse repetition frequency and a possible base line shift. 3.7 average frequency of the Doppler spectrum parameter estimated by clinical Doppler systems for the short-time average in a Doppler spectrum, ignoring the contributions from noise NOTE The average frequency of

47、the Doppler spectrum is generally determined for a small time interval, typically 2 ms to 20 ms). Unit: hertz, Hz 3.8 axial response range depth range in tissue over which a signal from a specific target plus noise is at least 3 dB above the noise level see 2.4.1 of IEC 61206 Unit: millimetre, mm 3.

48、9 blood-mimicking fluid (BMF) fluid which simulates blood acoustically and is moved at a known flow rate through the flow Doppler test object 3.10 channel separation ratio of the signal level in the signal channel corresponding to the movement in the test object (the desired output voltage) and the

49、signal level in the opposite channel (the undesired output voltage) NOTE Channel separation is to be quoted in decibels as twenty times the logarithm of the desired output to the undesired output voltage. see 2.6.1 of IEC 61206 Unit: decibel, dB 8 61685 IEC:2001(E) 3.11 colour display spatial resolution minimum separation in space for which two separate moving point targets or line targets can be resolved NOTE