1、BRITISH STANDARD BS 7887:1997 IEC 1390:1996 Ultrasonics Real-time pulse-echo systems Guide for test procedures to determine performance specifications ICS 11.040.50BS7887:1997 This British Standard, having been prepared under the directionof the Electrotechnical Sector Board, was published underthe
2、authority of the Standards Board and comes intoeffect on 15March1997 BSI 11-1998 The following BSI references relate to the work on this standard: Committee reference EPL/87 Draft for comment 91/20276 DC ISBN 0 580 26627 3 Committees responsible for this British Standard The preparation of this Brit
3、ish Standard was entrusted to Technical Committee EPL/87, Ultrasonics, upon which the following bodies were represented: Association of British Health-Care Industries British Dental Association British Institute of Radiology British Medical Ultrasound Society British Society for Rheumatology Departm
4、ent of Health Institution of Electrical Engineers Institution of Physics and Engineering in Medicine and Biology National Physical Laboratory Institute of Laryngology and Otology Amendments issued since publication Amd. No. Date CommentsBS 7887:1997 BSI 11-1998 i Contents Page Committees responsible
5、 Inside front cover National foreword ii Introduction 1 1 Scope 1 2 Normative references 1 3 Definitions 2 4 Environmental conditions 4 5 Equipment required 4 6 Test methods 4 6.1 Instruments 4 6.2 Test settings 5 6.3 Test parameters 6 Annex A (normative) Test objects and tissue-mimicking material 1
6、0 Annex B (informative) Bibliography 17 Figure A.1 Soft tissue-mimicking test object 11 Figure A.2 Axial resolution test object 12 Figure A.3 Resolution test object 13 Figure A.4 Contrast test object 14 Figure A.5 Non-scattering spheres test object 15 Figure A.6 Slice thickness measurement and calcu
7、lation 16 List of references Inside back coverBS7887:1997 ii BSI 11-1998 National foreword This British Standard has been prepared by Technical Committee EPL/87 and is identical with Technical Report IEC 1390:1996 Ultrasonics Real-time pulse-echo systems Test procedures to determine performance spec
8、ifications, published by the International Electrotechnical Committee (IEC). A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself conf
9、er immunity from legal obligations. Cross-references International standard Corresponding British Standard IEC 50 (801):1994 BS 4727 Glossary of electrotechnical power, telecommunications, electronics, lighting and colour terms Part 3: Terms particular to telecommunications and electronics Part 3:Gr
10、oup 08:1995 Acoustics and electroacoustics (Identical) IEC 866:1987 BS 7041:1989 Specification for characteristics and calibration of hydrophones for operation in the frequency range 0.5MHz to 15MHz (Identical) IEC 1102:1991 BS EN 61102:1994 Specification for measurement and characterisation of ultr
11、asonic fields using hydrophones in the frequency range of 0.5MHz to 15MHz (Identical) IEC 1157:1992 BS EN 61157:1995 Requirements for the declaration of the acoustic output of medical diagnostic ultrasonic equipment (Identical) Summary of pages This document comprises a front cover, an inside front
12、cover, pages i and ii, pages1 to 18, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on theinside front cover. BS 7887:1997 BSI 11-1998 1 Introduction An ultrasonic puls
13、e-echo scanner produces images of tissue in a scan plane by sweeping a narrow pulsed beam of ultrasound through the section of interest and detecting the echoes generated at tissue boundaries. A variety of transducer types is employed to operate in a transmit/receive mode for the ultrasonic signals.
14、 Ultrasonic scanners are widely used in medical practice to produce images of many soft-tissue organs throughout the human body. This technical report describes test procedures which should be widely acceptable and valid for a wide range of types of equipment. Manufacturers should use the report to
15、prepare their specifications, the users should use the report to check specifications. The measurements can also be carried out without interfering with the normal working conditions of the machine. The structures of the test objects have not been specified in detail rather, suitable types of overal
16、l and internal structures are described, together with typical test objects, in annex A. The specific structure of a test object should be reported, together with the results obtained using it. Similar commercial versions of these test objects are also available. The performance parameters specified
17、, and the corresponding methods of measurement have been chosen to provide a basis for comparison with the manufacturers specifications and between similar types of apparatus of different makes, intended for the same kind of diagnostic application. The manufacturers specifications should allow compa
18、rison with the results obtained from the tests in this report. Specific values of parameters and the tolerances on them have not been recommended, since these are constantly changing. Furthermore, it is intended that the sets of results and values obtained from the use of the recommended methods wil
19、l provide useful criteria for predicting the performance of equipment in appropriate diagnostic application. The procedures recommended in this report are in accordance with IEC 601-1 9 1) . Where a diagnostic system accommodates more than one option in respect of a particular system component, for
20、example the transducer, it is intended that each option be regarded as a separate system. However, it is considered that the performance of a machine is adequately specified if measurements are undertaken for the most significant combinations of machine control settings and accessories. Further eval
21、uation of equipment is obviously possible, but this should be considered as a special case rather than a routine requirement. Data relating to measuring methods, principles and equipment that are common to two or more sections of this report are given in annex A. The measurement of acoustic output p
22、ower levels and the assessment of electrical safety are dealt with in other IEC standards, and are therefore specifically excluded from this report. 1 Scope This technical report describes methods of measuring the performance of real-time medical ultrasonic imaging equipment in the frequency range 0
23、,5MHz to 15MHz. This report is relevant for real-time ultrasonic scanners based on the pulse-echo principle, for the types listed below: mechanical sector scanner; electronic phased array sector scanner; electronic linear array scanner; electronic curved array sector scanner; water-bath scanner base
24、d on any of the above four scanning mechanisms. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this technical report. At the time of publication, the editions indicated were valid. All normative documents ar
25、e subject to revision, and parties to agreements based on this Technical report are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. IEC 50(
26、801):1994, International Electrotechnical Vocabulary (IEV) Chapter 801: Acoustics and electroacoustics. IEC 854:1986, Methods of measuring the performance of ultrasonic pulse-echo diagnostic equipment. 1) Figures in square brackets refer to the bibliography given in annex B.BS7887:1997 2 BSI 11-1998
27、 IEC 866:1987, Characteristics and calibration of hydrophones for operation in the frequency range 0,5MHz to 15MHz. IEC 1102:1991, Measurement and characterisation of ultrasonic fields using hydrophones in the frequency range 0,5MHz to 15MHz. Amendment1(1993) IEC 1157:1992, Requirements for the decl
28、aration of the acoustic output of medical diagnostic ultrasonic equipment. 3 Definitions For the purpose of this technical report, the following definitions apply: 3.1 A-scan class of data acquisition geometry in one dimension, in which echo information is acquired from points lying along a single u
29、ltrasonic beam axis 3.20 of IEC854 modified 3.2 acoustic scan lines lines in a B-mode image, related directly to the transmission/reception cycle of echo collection 3.3 acoustic-working-frequency bandwidth difference in the frequencies f 1and f 2at which the amplitude of the acoustic pressure spectr
30、um is 3dB below the peak amplitude 3.62 of IEC1102 modified 3.4 acoustic-working frequency frequency 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. The signal
31、is analyzed either using the zero-crossing frequency technique or using a spectrum analysis method 3.4 of IEC1102 modified 3.5 amplitude-modulated display (A-mode) method of presentation of A-scan information in which the ultrasonic transducer-target distance is represented on one axis (normally hor
32、izontal) and the echo amplitude on the other 3.17 of IEC854 modified 3.6 automatic time gain compensation (ATGC) compensation for the attenuation in ultrasonic pulse amplitude with depth by deriving a compensating gain control function from the observed decrease in echo amplitudes 3.7 axial resoluti
33、on minimum separation along the ultrasonic beam axis of two targets at a specified depth in a tissue-mimicking test object for which two echo signals can be displayed 3.8 backscatter coefficient mean acoustic power scattered in the 180 direction by a specified object with respect to the direction of
34、 the incident beam, per unit solid angle per unit volume, divided by the incident beam intensity. The scatterers are considered to be randomly distributed. The mean power is obtained from different spatial realisations of the scattering volume. This is commonly referred to as the differential scatte
35、ring cross-section per unit volume in the 180 direction 3.9 backscatter contrast difference between the backscatter coefficient of two objects divided by the greater of the two backscatter coefficients 3.10 B-scan class of data acquisition geometry in which echo information is acquired from points l
36、ying in a scanned plane insonated by an interrogating ultrasonic beam 3.21 of IEC854 modified 3.11 brightness-modulated display (B-mode) method of presentation of B-scan information in which a particular section through an imaged object is represented in a conformal way by the plane of the display,
37、and echo amplitude is represented by local brightness or optical density of the display 3.18 of IEC854 modified 3.12 contrast-detail detectability minimum diameter of an object, at specified control settings and range, which can be distinguished on the display with a specified level of confidence, a
38、s a function of the backscatter contrast of the object with respect to the background 3.13 contrast-detail resolution minimum difference in echo amplitude which can be detected for a scattering or reflecting structure of specified properties, embedded in a particular tissue-mimicking material.The sp
39、ecified properties include shape, size or speed of soundBS 7887:1997 BSI 11-1998 3 3.14 dead zone distance from the test object scanning surface to the nearest test object wire which can be unequivocally imaged 3.15 depth of penetration maximum depth in the tissue-mimicking material of the test obje
40、ct beyond which the speckle pattern echoes are no longer detectable 3.16 display error distance between the centre of the image of a wire in the overall image of a test object and its correct position, as specified by the test object dimensions 3.17 display frame rate rate at which complete images a
41、re presented on the output display 3.18 displayed dynamic range ratio, expressed in decibels, of the amplitude of the maximum echo that does not saturate the display to the minimum echo that can be distinguished in the display under the scanner test settings 3.19 field-of-view area in the scan plane
42、 which is insonated by the ultrasound beam during the acquisition of echo data to produce one image frame 3.20 frame rate number of sweeps the ultrasonic beam makes per second through the field-of-view 3.21 gray scale range of values of image brightness, being either continuous between two extreme v
43、alues or, if discontinuous, including discrete values 3.14 of IEC854 modified 3.22 lateral resolution minimum separation in the scan plane of two line targets perpendicular to the ultrasonic beam axis at a specified depth in a tissue-mimicking test object for which two distinct echo signals can be d
44、isplayed 3.23 line density number of acoustic scan lines of echo information at a specified point in the image which cross a line of 1 cm length perpendicular to the beam and centred on the point 3.24 M-scan (time-motion scan) class of acquisition geometry in which echo information from moving struc
45、tures is acquired from points lying along a single beam axis. The echo information is presented using an M-mode display 3.25 maximum depth of penetration maximum depth at which the speckle pattern related to the scatterers in the tissue-mimicking test object can be displayed 3.26 nominal frequency u
46、ltrasonic frequency of operation of a system as quoted by the designer or manufacturer 3.7 of IEC854 3.27 real-time B-scan class of data acquisition and presentation in which B-scans are automatically and repetitively performed at display frame rates typically greater than five per second 3.28 recor
47、ding error distance between the centre of the image of a wire in the overall record of a test object and its correct position, as specified by the test object dimensions 3.29 scan plane plane containing ultrasonic scan lines 3.38 of IEC1102 modified 3.30 slice thickness thickness, perpendicular to t
48、he scan plane and at a stated depth in the test object, of that region of the test object from which acoustic information is displayed 3.31 speckle pattern image pattern produced by the interference of echoes from the scattering centres in tissue-mimicking material 3.32 spherical void sphere of mate
49、rial containing no scattering centres 3.33 test object device containing one or more groups of object configurations embedded in a tissue-mimicking materialBS7887:1997 4 BSI 11-1998 3.34 test object scanning surface surface on the tissue-mimicking test object recommended for ultrasonic transducer location during a test procedure 3.35 time gain compensation (TGC) change in amplifier gain with time introduced to compensate for loss in echo amplitude with increasing depth due to attenuation in tissue 3.36 time-motion mode (M-mo
