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1、BRITISH STANDARD BS EN 61828:2002 IEC 61828:2001 Ultrasonics Focusing transducers Definitions and measurement methods for the transmitted fields The European Standard EN 61828:2001 has the status of a British Standard ICS 17.140.50 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT L
2、AW Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 08 03:07:22 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 61828:2002 This British Standard, having been prepared under the direction of the Electrotechnical Sector Policy and Strategy Committee, was published under the authority of the Standa
3、rds Policy and Strategy Committee on 21 February 2002 BSI 21 February 2002 ISBN 0 580 39012 8 National foreword This British Standard is the official English language version of EN 61828:2001. It is identical with IEC 61828:2001. The UK participation in its preparation was entrusted to Technical Com
4、mittee EPL/87, Ultrasonics, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. From 1 January 1997, all IEC publications have the number 60000 added to the old number. For instance, IEC 27-1 has been renumbered as IEC 6
5、0027-1. For a period of time during the change over from one numbering system to the other, publications may contain identifiers from both systems. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Stand
6、ards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible f
7、or their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK
8、interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 51 and a back cover. The BSI copyright date displayed in this document indicates whe
9、n the document was last issued. Amendments issued since publication Amd. No. DateComments Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 08 03:07:22 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EUROPEAN STANDARDEN 61828 NORME EUROPENNE EUROPISCHE NORMOctober 2001 CENELEC European Committee for El
10、ectrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B - 1050 Brussels 2001 CENELEC -All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref
11、. No. EN 61828:2001 E ICS 17.140.50 English version Ultrasonics - Focusing transducers - Definitions and measurement methods for the transmitted fields (IEC 61828:2001) Ultrasons - Transducteurs focaliseurs - Dfinitions et mthodes de mesure des champs transmis (CEI 61828:2001) Ultraschall - Fokusier
12、ende Wandler - Definitionen und Messverfahren fr die erzeugten Felder (IEC 61828:2001) This European Standard was approved by CENELEC on 2001-09-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the stat
13、us of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member. This European Standard exists in three official versions (English, French, German).
14、 A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republ
15、ic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 08 03:07:22 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 82816:2001- 2 - Forew
16、ord The text of document 87/196/FDIS, future edition 1 of IEC 61828, prepared by IEC TC 87, Ultrasonics, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 61828 on 2001-09-01. The following dates were fixed: latest date by which the EN has to be implemented at national
17、 level by publication of an identical national standard or by endorsement(dop)2002-06-01 latest date by which the national standards conflicting with the EN have to be withdrawn(dow)2004-09-01 Annexes designated “normative“ are part of the body of the standard. Annexes designated “informative“ are g
18、iven for information only. In this standard, annex ZA is normative and annexes A, B and C are informative. Annex ZA has been added by CENELEC. _ Endorsement notice The text of the International Standard IEC 61828:2001 was approved by CENELEC as a European Standard without any modification. In the of
19、ficial version, for Bibliography, the following notes have to be added for the standards indicated: IEC 61161:1992NOTE: Harmonized as EN 61161:1994 (not modified). IEC 62092:2001NOTE: Harmonized as EN 62092:2001 (not modified). _ 2 egaP 1002:82816 NE 2002 yraurbeF 81 ISB Page 2 EN 61828:2001 BSI 21
20、February 2002 Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 08 03:07:22 GMT+00:00 2006, Uncontrolled Copy, (c) BSI CONTENTS INTRODUCTION 5 1Scope 6 2Normative references. 6 3General . 7 3.1Focusing transducers . 7 3.1.1Focusing methods. 7 3.1.2Known and unknown focusing transducers 7 3.1.3Focu
21、sing and beamwidth 8 3.1.4New focusing parameter definitions 8 3.1.5Applications of focusing definitions . 9 3.1.6Relation of present definitions to physiotherapy transducers (treatment heads) . 9 3.2System and measurement requirements . 9 3.2.1Transmitted pressure waveforms 9 3.2.2Radiated fields 9
22、 3.3General focused field descriptions.10 3.3.1General field descriptions for transducers of known construction .10 3.3.2The scan plane and the steering of beams.11 4Focusing definitions12 4.1Background information.12 4.2Definitions .12 5List of symbols23 6Measurement procedures .24 6.1General .24 6
23、.1.1Set-up25 6.2Finding the beam axis25 6.3Determining if transducer is focusing .27 6.4Measuring other focal parameters of a focusing transducer .28 Annex A (informative) Background for the transmission/ Characteristics of focusing transducers.38 Annex B (informative) Methods for determining the be
24、am axis for well-behaved beams 44 B.1Comparisons of beam axis search methods.44 B.2Beamwidth midpoint method45 Annex C (informative) Methods for determining the beam axis for beams that are not well-behaved 48 Annex ZA (normative) Normative references to international publications with their corresp
25、onding European publications51 3 egaP 1002:82816 NE Page 3 EN 61828:2001 BSI 21 February 2002 Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 08 03:07:22 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Figure 1 Transducer options Top: Transducer with a radius of curvature R and a focal length equal t
26、o R Middle: Transducer with a plano-concave lens Bottom: Transducer with a plano-convex lens.29 Figure 2 Definitions for focusing measurements when the transducer geometry is unknown .30 Figure 3 Field parameters for non-focusing and focusing transducers 31 Figure 4 Beam contour plot Contours at 6,
27、12, and 20 dB for a 5 MHz transducer with a diameter of 25 mm and a radius of curvature of 50 mm centred at location 0,0 (bottom centre of graph)32 Figure 5 Parameters for describing a focusing transducer of a known geometry.33 Figure 6 Path difference parameters for describing a focusing transducer
28、 of a known geometry.34 Figure 7 Beamwidth focus in a principal longitudinal plane.35 Figure 8 Types of geometric focusing36 Figure 9 Pressure focus in a principal longitudinal plane 37 Figure B.1 X-axis scan at 9 cm depth for the first focal zone with beam centre.45 Figure B.2 X-axis scan at 4,4 cm
29、 depth for the second focal zone 46 Figure C.1 Asymmetric beam showing beamwidth midpoint method .49 Table B.1 Standard deviations for x and y scans using three methods of determining the centre of the beam 44 Table B.2 dB beamwidth levels for determining midpoints .47 4 egaP 1002:82816 NE Page 4 EN
30、 61828:2001 BSI 21 February 2002 Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 08 03:07:22 GMT+00:00 2006, Uncontrolled Copy, (c) BSI INTRODUCTION Focusing transducers are essential in medical applications for obtaining high-resolution images, Doppler and flow data and for concentrating ultras
31、onic energy at desired sites for therapy. Present terminology for focusing transducers is inadequate for communicating precisely the characteristics of the focused fields of the wide variety of transducers and transducer array types and focusing means in common usage. This International Standard pro
32、vides specific definitions appropriate for describing the focused field from a theoretical viewpoint for transducers with known characteristics intended by design. Other specific definitions included in this standard, based on measurement methods, provide a means of determining focusing properties,
33、if any, of a transducer of unknown field characteristics. The measurement method and definitions provide criteria for determining if the transducer is focusing, as well as a means of describing the focusing properties of the field. Beam axis alignment methods are given for focusing transducers. 5 eg
34、aP 1002:82816 NE 2002 yraurbeF 81 ISB Page 5 EN 61828:2001 BSI 21 February 2002 Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 08 03:07:22 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ULTRASONICS FOCUSING TRANSDUCERS DEFINITIONS AND MEASUREMENT METHODS FOR THE TRANSMITTED FIELDS 1 Scope This Inte
35、rnational Standard ? provides definitions for the transmitted field characteristics of focusing transducers for applications in medical ultrasound; ? relates these definitions to theoretical descriptions, design, and measurement of the transmitted fields of focusing transducers; ? gives measurement
36、methods for obtaining defined characteristics of focusing transducers; ? specifies beam axis alignment methods appropriate for focusing transducers. This International Standard relates to focusing ultrasonic transducers operating in the frequency range appropriate to medical ultrasound (0,5 MHz to 4
37、0 MHz) for both therapeutic and diagnostic applications. It shows how the characteristics of the transmitted field of transducers may be described from the point of view of design, as well as measured by someone with no prior knowledge of the construction details of a particular device. The radiated
38、 ultrasound field for a specified excitation is measured by a hydrophone in either a standard test medium (for example, water) or in a given medium. The standard applies only to media where the field behaviour is essentially like that in a fluid (i.e. where the influence of shear waves and elastic a
39、nisotropy is small), including soft tissues and tissue-mimicking gels. Any aspects of the field that affect their theoretical description or are important in design are also included. These definitions would have use in scientific communications, system design and description of the performance and
40、safety of systems using these devices. This standard incorporates definitions from other related standards1 where possible, and supplies new, more specific terminology, both for defining focusing characteristics and for providing a basis for measurement of these characteristics. 2 Normative referenc
41、es 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 publications do not apply. However parties to agreements based on this In
42、ternational 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 applies. Members of ISO and IEC maintain registers of currently valid I
43、nternational Standards. IEC 60050(801):1994, International Electrotechnical Vocabulary (IEV) Chapter 801: Acoustics and electroacoustics IEC 61102:1991, Measurement and characterization of ultrasonic fields using hydrophones in the frequency range 0,5 MHz to 15 MHz _ 1 Specifically, IEC 61102 and IE
44、C 61157 (see clause 2). 6 egaP 1002:82816 NE 2002 yraurbeF 81 ISB Page 6 EN 61828:2001 BSI 21 February 2002 Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 08 03:07:22 GMT+00:00 2006, Uncontrolled Copy, (c) BSI IEC 61157:1992, Requirements for the declaration of the acoustic output of medical di
45、agnostic ultrasonic equipment IEC 61689:1996, Ultrasonics Physiotherapy systems Performance requirements and methods of measurement in the frequency range 0,5 MHz to 5 MHz 3 General The information contained in this clause is an introduction to the definitions given in clause 4 and the measurement m
46、ethods given in clause 6. 3.1 Focusing transducers The term “focusing transducer“2 is commonly used for a device which has a smaller beamwidth in some regions of the field than a device which is “non-focusing“. A “non- focusing transducer“ can still have a natural focus, so it is necessary to distin
47、guish a focusing transducer as having a greater concentration of pressure amplitude (for a given power output) than a non-focusing transducer at its natural focus. For example, a non- focusing transducer made of a simple disc of uniformly poled piezoelectric material has a beam whose intensity at it
48、s natural focus can be as much as four times the average intensity at the source, and whose 6 dB beamwidth can be approximately half of that at the source. A definition of a focusing transducer is given in 4.2.33 to make a quantitative distinction between focusing and non-focusing transducers. 3.1.1
49、 Focusing methods The simplest means of intentionally focusing an ultrasonic transducer, borrowed from analogous optical principles, is that of shaping the ultrasonic transducer into a concave form or adding to it a physical lens as illustrated in figure 1. In the top part of this figure, a transducer curved with a radius R is shown focusing to the centre of curvature, where R is positive by convention. By the geometrical-optics approximation, the focal length F is equal to R and