EN 62555-2014 en Ultrasonics - Power measurement - High intensity therapeutic ultrasound (HITU) transducers and systems.pdf

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1、BSI Standards PublicationUltrasonics Power measurement High intensitytherapeutic ultrasound (HITU)transducers and systemsBS EN 62555:2014National forewordThis British Standard is the UK implementation of EN 62555:2014. It is identical to IEC 62555:2013.The UK participation in its preparation was ent

2、rusted to TechnicalCommittee EPL/87, Ultrasonics.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisions ofa contract. Users are responsible for its correct application. The British Sta

3、ndards Institution 2014.Published by BSI Standards Limited 2014ISBN 978 0 580 69088 4ICS 17.140.50Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 31 May 2014.Amend

4、ments/corrigenda issued since publicationDate Text affectedBRITISH STANDARDBS EN 62555:2014EUROPEAN STANDARD EN 62555 NORME EUROPENNE EUROPISCHE NORM April 2014 CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elek

5、trotechnische Normung CEN-CENELEC Management Centre: Avenue Marnix 17, B - 1000 Brussels 2014 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 62555:2014 E ICS 17.140.50 English version Ultrasonics - Power measurement - High intens

6、ity therapeutic ultrasound (HITU) transducers and systems (IEC 62555:2013) Ultrasons - Mesurage de puissance - Transducteurs et systmes ultrasonores thrapeutiques de haute intensit (HITU) (CEI 62555:2013) Ultraschall - Leistungsmessung - Messung der Ausgangsleistung fr hochintensive, therapeutische

7、Ultraschallwandler und -systeme (IEC 62555:2013) This European Standard was approved by CENELEC on 2013-12-24. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any

8、alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CENELEC member. This European Standard exists in three official versions (English, French, German). A version in any other lang

9、uage made by translation under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the

10、 Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the Unite

11、d Kingdom. BS EN 62555:2014EN 62555:2014 - 2 - Foreword The text of document 87/538/FDIS, future edition 1 of IEC 62555, prepared by IEC TC 87 “Ultrasonics“ was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as EN 62555:2014. The following dates are fixed: latest date by which th

12、e document has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2014-10-25 latest date by which the national standards conflicting with the document have to be withdrawn (dow) 2016-12-24 Attention is drawn to the possibility that some of th

13、e elements of this document may be the subject of patent rights. CENELEC and/or CEN shall not be held responsible for identifying any or all such patent rights. Endorsement notice The text of the International Standard IEC 62555:2013 was approved by CENELEC as a European Standard without any modific

14、ation. In the official version, for Bibliography, the following notes have to be added for the standards indicated: IEC 62127-2 NOTE Harmonized as EN 62127-2 IEC 60601-2-62 NOTE Harmonized as EN 60601-2-62 BS EN 62555:2014- 3 - EN 62555:2014 Annex ZA (normative) Normative references to international

15、 publications with their corresponding European publications The 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 re

16、ferenced document (including any amendments) applies. NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD applies. Publication Year Title EN/HD Year IEC 61161 2013 Ultrasonics - Power measurement - Radiation force balances and perf

17、ormance requirements EN 61161 2013 IEC/TR 62781 Ultrasonics - Conditioning of water for ultrasonic measurements - - BS EN 62555:2014 2 62555 IEC:2013 CONTENTS INTRODUCTION . 7 1 Scope 8 2 Normative references 8 3 Terms and definitions 8 4 List of symbols 11 5 Power measurement for HITU equipment. 12

18、 6 Radiation force on a target 13 6.1 General 13 6.2 Requirements for equipment 14 6.2.1 Target type . 14 6.2.2 Target diameter 15 6.2.3 Balance / force measuring system 15 6.2.4 System tank 15 6.2.5 Target support structures 15 6.2.6 Transducer positioning . 15 6.2.7 Anti-streaming foils . 15 6.2.8

19、 Transducer coupling . 16 6.2.9 Calibration and stability 16 6.3 Requirements for measuring conditions . 16 6.3.1 Lateral target position . 16 6.3.2 Transducer/target separation 16 6.3.3 Water . 16 6.3.4 Water contact . 17 6.3.5 Environmental conditions 17 6.3.6 Thermal drifts . 17 6.4 Measurement u

20、ncertainty . 17 6.4.1 General 17 6.4.2 Non-planar ultrasound field . 17 6.4.3 Balance system with target suspension. 17 6.4.4 Linearity and resolution of the balance system 17 6.4.5 Extrapolation to the moment of switching the ultrasonic transducer 18 6.4.6 Target imperfections . 18 6.4.7 Reflecting

21、 target geometry 18 6.4.8 Lateral absorbers in the case of reflecting target measurements 18 6.4.9 Target misalignment . 18 6.4.10 Ultrasonic transducer misalignment 18 6.4.11 Water temperature 18 6.4.12 Ultrasonic attenuation and acoustic streaming 19 6.4.13 Foil properties 19 6.4.14 Finite target

22、size . 19 6.4.15 Environmental influences 19 6.4.16 Excitation voltage measurement . 19 6.4.17 Ultrasonic transducer temperature 19 6.4.18 Nonlinearity 19 BS EN 62555:201462555 IEC:2013 3 6.4.19 Other sources . 19 6.5 Calculation of output power 20 7 Buoyancy change of a target . 20 7.1 General 20 7

23、.2 Requirements for equipment 21 7.2.1 Target type . 21 7.2.2 Entry window diameter 22 7.2.3 Balance / force measuring system 22 7.2.4 System tank 22 7.2.5 Target support structures 22 7.2.6 Transducer positioning . 22 7.2.7 Anti-streaming foils . 22 7.2.8 Transducer coupling . 23 7.2.9 Calibration

24、23 7.3 Requirements for measuring conditions . 23 7.3.1 Lateral target position . 23 7.3.2 Transducer/Target separation . 23 7.3.3 Water . 23 7.3.4 Water contact . 24 7.3.5 Environmental conditions 24 7.3.6 Thermal drifts . 24 7.4 Measurement uncertainty . 24 7.4.1 General 24 7.4.2 Buoyancy sensitiv

25、ity . 24 7.4.3 Non-planar ultrasound field . 24 7.4.4 Balance system including target suspension . 24 7.4.5 Linearity and resolution of the balance system 24 7.4.6 Curve-fitting and extrapolation 25 7.4.7 Water temperature 25 7.4.8 Ultrasonic attenuation and acoustic streaming 25 7.4.9 Foil properti

26、es 25 7.4.10 Finite target size . 25 7.4.11 Environmental influences 25 7.4.12 Excitation voltage measurement . 25 7.4.13 Ultrasonic transducer temperature 26 7.4.14 Nonlinearity 26 7.4.15 Other sources . 26 7.5 Calculation of output power 26 8 Electrical characteristics 26 8.1 Electrical impedance

27、26 8.2 Radiation conductance . 26 8.3 Efficiency . 27 Annex A (informative) Other measurement methods 28 Annex B (informative) Target size 29 Annex C (informative) Formulae for radiation force 31 Annex D (informative) Expansion method 36 Annex E (informative) Influence of attenuation and acoustic st

28、reaming on determining incident and output powers . 42 BS EN 62555:2014 4 62555 IEC:2013 Annex F (informative) Avoidance of cavitation 45 Annex G (informative) Transducer efficiency 46 Bibliography 54 Figure 1 Linearity check: balance readout as a function of the input quantity . 20 Figure C.1 Corre

29、ction factor of plane wave for the acoustic field of a circular plane piston ultrasonic transducer as a function of the product of the circular wavenumber and transducer radius . 33 Figure D.1 Schematic diagram of an expansion target. 36 Figure D.2 Example of weight vs time sequence 37 Figure D.3 Ti

30、me history of the apparent mass of the castor oil target at different frequencies following an insonation of approximately 1 W acoustic power for a period of 10 s 40 Figure G.1 Electrical voltage source under different loading conditions 52 Figure G.2 Electrical voltage source and electrical matchin

31、g network and transducer equivalent circuit . 52 Figure G.3 Diagram illustrating electrical loss. . 53 Table D.1 Selected properties of Acros Organics castor oil in the range 10 C to 60 C 39 Table D.2 Absorption coefficient of castor oil as a function of temperature . 41 BS EN 62555:201462555 IEC:20

32、13 7 INTRODUCTION In ultrasound fields at megahertz frequencies, output power is typically determined by measuring the force on a target using a radiation force balance 1,2,3. However, the relationship between the radiation force and the output power is affected by the focusing or other geometrical

33、aspects of the field, by the type and shape of the target, by the distance of the target from the transducer, by absorption (including shock-loss) in the water path, and by acoustic streaming currents. Whilst many of these effects are small for typical diagnostic or physiotherapy ultrasound fields,

34、they cannot generally be ignored for HITU fields (particularly for those often referred to as high intensity focused ultrasound HIFU) 4. Furthermore, in HITU, the quantity of interest is the power incident on the patient rather than the output power at the transducer face. Since it is common to have

35、 a water stand-off between the transducer and the patient, attenuation and shock-loss in the water path may be significant and will vary depending upon the chosen distance. The purpose of this International Standard is to establish standard methods of measurement of ultrasonic power of HITU devices

36、in liquids in the lower megahertz frequency range based on the measurement of the radiation force using a gravimetric balance, and calorimetry (based on the measurement of thermal expansion). This standard identifies the sources of errors and describes a systematic step-by-step procedure to assess o

37、verall measurement uncertainty as well as the precautions that should be undertaken and uncertainties that should be taken into account while performing power measurements. Practical guidance is given for the determination of acoustic power from the very wide range of transducer geometries used for

38、HITU. Unlike radiation force approaches in IEC 61161 that deal with “time average power,” other power measurement methods are described in this document. The structure and content of parts of this International Standard are largely based on IEC 61161:2013 but there are differences that are summarise

39、d below. In this standard the prime measurand is considered to be the incident power, and not the output power. Output power is always the quantity of interest in IEC 61161, which specifies that measurements are made with the target placed close to the transducer. However, this may not always be pos

40、sible for strongly convergent transducers and there are cases where it is more relevant to measure the incident power which reaches a specified surface at some substantial distance from the transducer (this surface may represent the skin surface of the patient, for instance). This extra distance may

41、 result in significant nonlinear loss in the water path even at low megahertz frequencies. Consequently, in this International Standard the prime measurand is considered to be the incident power, and not the output power. The incident power may of course be the basis for determining the output power

42、 using an appropriate model with its own uncertainties. BS EN 62555:2014 8 62555 IEC:2013 ULTRASONICS POWER MEASUREMENT HIGH INTENSITY THERAPEUTIC ULTRASOUND (HITU) TRANSDUCERS AND SYSTEMS 1 Scope This International Standard establishes general principles relevant to HITU fields for the use of radia

43、tion force balances in which an obstacle (target) intercepts the sound field to be measured; specifies a calorimetric method of determining the total emitted acoustic power of ultrasonic transducers based on the measurement of thermal expansion of a fluid-filled target; specifies requirements relate

44、d to the statement of electrical power characteristics of ultrasonic transducers; provides guidance related to the avoidance of acoustic cavitation during measurement; provides guidance related to the measurement of HITU transducers of different construction and geometry, including collimated, diver

45、ging and convergent transducers, and multi-element transducers; provides guidance on the choice of the most appropriate measurement method; provides information on assessment of overall measurement uncertainties. This International Standard is applicable to the measurement of ultrasonic power genera

46、ted by HITU equipment up to 500 W in the frequency range from 0,5 MHz to 5 MHz. HITU equipment may generate convergent, collimated or divergent fields. For frequencies less than 500 kHz, no validations exist and the user should assess the uncertainties of the power measurement and measurement system

47、 at the frequencies of operation. This International Standard does not apply to: ultrasound equipment used for physiotherapy, for lithotripsy for general pain relief. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensabl

48、e 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 61161:2013, Ultrasonics Power measurement Radiation force balances and performance requirements IEC/TR 62781, Ult

49、rasonics Conditioning of water for ultrasonic measurements 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. BS EN 62555:201462555 IEC:2013 9 3.1 acoustical efficiency aratio of the acoustic output power from an ultrasonic transducer to the transducer electrical power Note 1 to entry: Acoustical efficiency is unitless. 3.2 acoustic streaming bulk fluid motion initiated by a sound field SOURCE: IEC 61161:2013, 3.1