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1、BRITISH STANDARD BS 5724-3.26: 1990 Medical electrical equipment Part 3: Particular requirements for performance Section 3.26 Method for declaring parameters for ultrasonic diagnostic equipment using test objects UDC 615.47:62-83:621.31 + 620.179.16.004.15 Licensed Copy: sheffieldun sheffieldun, na,
2、 Fri Dec 01 13:52:58 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5724-3.26:1990 This British Standard, having been prepared under the direction of the Health Care Standards Policy Committee, was published under the authority of the Board of BSI and comes into effect on 29 June 1990 BSI 06-1999 The
3、 following BSI references relate to the work on this standard: Committee reference HCC/111 Draft for comment 87/52777 DC ISBN 0 580 17884 6 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Health Care Standards Policy Committee (HCC/-) to
4、 Technical Committee HCC/111, upon which the following bodies were represented: British Institute of Radiology College of Radiographers Department of Health Department of Trade and Industry (National Physical Laboratory) Electro-Medical Trade Association Limited Institute of Physical Sciences in Med
5、icine (IPSM) Ministry of Defence Ophalmological Society of the United Kingdom Scottish Health Services Amendments issued since publication Amd. No.Date of issueComments Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 13:52:58 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5724-3.26:1990 BSI 06
6、-1999i Contents Page Committees responsibleInside front cover Foreword2 Section 1. General 1Scope and object1 2Definitions1 Section 2. Preliminary test and operating conditions 3Preliminary test and operating conditions3 Section 3. Declaration and measurement of parameters 4Performance parameters5 5
7、Resolution5 6DEAD ZONE6 7SLICE THICKNESS6 8DEPTHS OF PENETRATION7 9DISPLAYED DYNAMIC RANGE7 10MAGNIFICATION ERRORS7 11REGISTRATION ERROR8 12ACCURACY OF THE CALLIPER8 13Presentation of performance parameters10 Section 4. Requirements for TEST-OBJECTS 14TEST-OBJECT design11 Appendix A Tissue-mimicking
8、 material12 Figure 1 Section through TEST-OBJECT CONFIGURATION 1 to determine AXIAL RESOLUTION, DEAD ZONE and DEPTHS OF PENETRATION when 2 MHz frequency 8 MHz13 Figure 2 Section through the REFERENCE PLANE of TEST-OBJECT CONFIGURATION 2 to determine LATERAL RESOLUTION when 2 MHz frequency 8 MHz14 Fi
9、gure 3 Section in a plane perpendicular to the REFERENCE PLANE of TEST-OBJECT CONFIGURATION 3 to determine SLICE THICKNESS when 2 MHz frequency 8 MHz15 Figure 4 Section through the REFERENCE PLANE of TEST-OBJECT CONFIGURATION 4 for the production of an ACOUSTIC GREY SCALE wedge when 2 MHz frequency
10、8 MHz16 Figure 5 Section through the REFERENCE PLANE of TEST-OBJECT CONFIGURATION 5 to determine MAGNIFICATION ERROR, REGISTRATION ERROR and ACCURACY OF THE CALLIPER when 2 MHz frequency 8 MHz17 Table 1 Specified values for the attenuation of sound in tissue-mimicking materials11 Publications referr
11、ed toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 13:52:58 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5724-3.26:1990 ii BSI 06-1999 Foreword This Section of BS 5724 has been prepared under the direction of the Health Care Standards Policy Committee. This British Standa
12、rd complements BS 5724 “Medical electrical equipment” Part 2 “Particular requirements for safety” Section 2.26 “Specification for ultrasonic medical diagnostic equipment”1), which will be identical with the corresponding international standard being prepared by the International Electrotechnical Com
13、mission (IEC). The Technical Committee responsible for this British Standard was unable to specify requirements for declaring performance in respect of low contrast detectability and was unable to specify a method of measuring back scatter in the tissue-mimicking material used in the TEST-OBJECTS. I
14、n this British Standard, it is assumed that a light image is displayed on a dark background. If the displaying image is a dark image on a light background, then the term DARK THRESHOLD should be replaced throughout by LIGHT THRESHOLD. Terms defined in this and other Parts of BS 5724 are written in c
15、apitals. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 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
16、 Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 18, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments in
17、corporated. This will be indicated in the amendment table on the inside front cover. 1) In preparation. Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 13:52:58 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5724-3.26:1990 BSI 06-19991 Section 1. General 1 Scope and object 1.1 Scope This Secti
18、on of BS 5724 describes the performance parameters to be stated in documents accompanying an ULTRASONIC MEDICAL DIAGNOSTIC EQUIPMENT as defined in 2.31, together with methods for evaluating its performance using specified TEST-OBJECTS. This Section of BS 5724 does not cover Doppler effect facilities
19、 of ULTRASONIC MEDICAL DIAGNOSTIC EQUIPMENT. 1.2 Object The object is to permit the direct comparison of ULTRASONIC MEDICAL DIAGNOSTIC EQUIPMENT of different manufacture, and to standardize methods for the determination of compliance with the manufacturers declared performance. 2 Definitions For the
20、 purposes of this Section of this British Standard, the following definitions apply. 2.1 accuracy of the calliper the difference between the length or area of a feature of a TEST-OBJECT and the value determined using the calliper. The difference is expressed as a percentage of the length or area 2.2
21、 accoustic grey scale an area of a TEST REGION, the position of which is identified in the TEST-OBJECT documentation, that displays a wide range of grey scale levels 2.3 central magnification letter symbols: acx and acy ratio of the length of the image, in the OUTPUT DISPLAY PLANE, of a given featur
22、e of a TEST-OBJECT, determined when the centre of the image is located at the CENTRE OF THE FIELD OF VIEW, to the length of the given feature. The image is aligned such that the length direction is either perpendicular to (subscript x) or parallel to (subscript y) the scan line passing through its c
23、entre 2.4 centre of the field of view a point on the centreline of the TEST-OBJECT, which is situated nearest to midway between the TEST-OBJECT SCANNING SURFACE and the MAXIMUM DEPTH OF PENETRATION 2.5 30 % dark threshold a TEST REGION is said to be at 30 % DARK THRESHOLD when approximately 30 % of
24、the region is at the lowest displayable grey level 2.6 70 % dark threshold a TEST REGION is said to be at 70 % DARK THRESHOLD when approximately 70 % of the region is at the lowest displayable grey level 2.7 dead zone the distance from the TEST-OBJECT SCANNING SURFACE to the first wire, the image of
25、 which is unequivocally displayed 2.8 displayed dynamic range the ratio 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 stated operating conditions 2.9 field of view that part of a TEST-OBJECT which is imaged
26、when scanned by the ULTRASOUND IMAGING SYSTEM with the transducer held stationary against the TEST-OBJECT SCANNING SURFACE and the scanner set to the appropriate settings 2.10 fine scale echoes echoes from bulk fine structure in the TEST-OBJECT 2.11 image region any region in the OUTPUT DISPLAY PLAN
27、E representing an area of more than one TEST REGION 2.12 30 % light threshold a TEST REGION is said to be at 30 % LIGHT THRESHOLD when approximately 30 % of the region is at the highest displayable grey level 2.13 70 % light threshold a TEST REGION is said to be at 70 % LIGHT THRESHOLD when approxim
28、ately 70 % of the region is at the highest displayable grey level 2.14 local magnification letter symbols: adx and ady Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 13:52:58 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5724-3.26:1990 2 BSI 06-1999 the ratio of the length of the image, in t
29、he OUTPUT DISPLAY PLANE, of a given feature of a TEST-OBJECT, determined when the centre of the image is located at the point under consideration, to the length of the given feature. The image is aligned such that the length direction is either perpendicular to (subscript x) or parallel to (subscrip
30、t y) the central scan line of the image 2.15 magnification error letter symbols: Vdx and Vdy. the difference between the CENTRAL MAGNIFICATION and the LOCAL MAGNIFICATION at a particular point in the FIELD OF VIEW for a given orientation, expressed as a percentage of the CENTRAL MAGNIFICATION 2.16 m
31、aximum depth of penetration the maximum depth at which the images of wires within the TEST-OBJECT can be obtained 2.17 normal depth of penetration the maximum depth in the TEST-OBJECT from which FINE SCALE ECHO information can be obtained under normal operating conditions 2.18 output display plane t
32、he optical plane in which the displayed output image lies 2.19 radial scanning system a scanning system which generates an essentially circular set of scan lines in a plane NOTEExamples of radial scanning systems include rotating transducers and phased array sector scanners. 2.20 rectilinear scannin
33、g system a scanning system which is capable of employing parallel or approximately parallel scan lines NOTEExamples of rectilinear scanning systems include linear arrays, manual contact B-scanners and stand-alone A-mode systems. A-mode facilities linked to an imaging system would be placed in the ca
34、tegory which defines that system. M-mode systems are considered as B-mode. 2.21 reference plane a plane so indicated on the external structure of the TEST-OBJECT 2.22 registration error the maximum distance between the centres of images of a wire in a TEST-OBJECT when referred to the TEST-OBJECT dim
35、ensions NOTEREGISTRATION ERROR applies only to scanners producing composite scans in two or more distinct directions. 2.23 scan plane a plane containing the ULTRASOUND scan lines 2.24 slice thickness the dimension, perpendicular to the SCAN PLANE, at a stated depth, of the material of the TEST-OBJEC
36、T from which accoustic information is displayed 2.25 test-object a device containing one or more groups of TEST-OBJECT CONFIGURATIONS immersed in a tissue-mimicking material 2.26 test-object configuration a group of wires or inserts within a TEST-OBJECT which is used for one or more performance meas
37、urements 2.27 test-object scanning surface a surface of the TEST-OBJECT through which the ULTRASOUND beam enters 2.28 test region any region in the OUTPUT DISPLAY PLANE representing a specified area in the TEST-OBJECT 2.29 ultrasound mechanical oscillation consisting of local compression, and rarefa
38、ction of the material, the frequency of which is above 20 kHz 2.30 ultrasound imaging system a system by means of which the position of an object in the SCAN PLANE is displayed as an output image in the OUTPUT DISPLAY PLANE 2.31 ultrasonic medical diagnostic equipment EQUIPMENT for the generation an
39、d application to PATIENTS of ULTRASOUND and intended for medical diagnostic investigation (hereafter referred to as EQUIPMENT) Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 13:52:58 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5724-3.26:1990 BSI 06-19993 Section 2. Preliminary test and ope
40、rating conditions 3 Preliminary test and operating conditions 3.1 General 3.1.1 The tests shall be undertaken using TEST-OBJECTS complying with section 4. NOTEThe TEST-OBJECT should be chosen such that its enclosure fits the ultrasonic probe(s) supplied with the equipment. 3.1.2 Scans shall be repea
41、ted through slightly different orientations until the studied feature is consistently imaged on all the scans. All measurements of axial and lateral resolution on RADIAL SCANNING SYSTEMS shall be made along the line of symmetry of the sector (0 measurement) and should if possible be repeated at an a
42、ngle of 30 to this line (30 measurement). 3.1.3 The tests shall be undertaken using the accessories and associated cables recommended in the ACCOMPANYING DOCUMENTS. 3.1.4 If manual gain controls are provided, they shall be used for the tests. If automatic gain control is the only method provided for
43、 the control of gain, measurements shall be made at scanning gain and this fact should be recorded. NOTETo ensure consistency in any set of results, the tests should be carried out by a single observer under a constant and subdued lighting level. 3.2 Initial scanner setting The EQUIPMENT shall be se
44、t up for scanning as recommended in the ACCOMPANYING DOCUMENTS. 3.3 Scanning gain 3.3.1 The scanning gain shall be set as described in 3.3.2 to 3.3.8. 3.3.2 Select initial settings according to 3.2. 3.3.3 Scan TEST-OBJECT CONFIGURATION 1 (see Figure 1) through TEST-OBJECT SCANNING SURFACE 1 in the R
45、EFERENCE PLANE. 3.3.4 Adjust all gain controls to maximize the depth of visualization of the FINE SCALE ECHOES in the OUTPUT DISPLAY PLANE. 3.3.5 Observe the average intensity level of the FINE SCALE ECHOES in the penultimate centimetre visualized. 3.3.6 Match the FINE SCALE ECHOES throughout the vi
46、sualized depth to that observed in the penultimate centimetre. Begin by using the near field controls if provided and use the minimum possible adjustment of controls which affect the far gain. 3.3.7 Adjust the overall gain to bring the overall FINE SCALE ECHO intensity level to the mid-range grey sc
47、ale. 3.3.8 Record the resulting position in all gain controls as the scanning gain setting. 3.4 Viewing screen settings, recording screen settings and camera settings 3.4.1 Viewing screen settings, recording screen settings and camera settings shall be established as described in 3.4.2 to 3.4.13. NO
48、TEThe selection of scanning gain as described in 3.3 is an essential preliminary to this procedure. 3.4.2 Scan TEST-OBJECT CONFIGURATION 1 through SCANNING SURFACE 1 in the REFERENCE PLANE. 3.4.3 Using, as a convenient test structure, the visualization of the axial beam profile groups (group D), adj
49、ust all focus controls available to the user that affect the screen focus so as to obtain the sharpest presentation of the image. 3.4.4 Scan TEST-OBJECT CONFIGURATION 4 (see Figure 4) through TEST-OBJECT SCANNING SURFACE 1 in the REFERENCE PLANE. 3.4.5 Determine an echo-free IMAGE REGION. Reduce the contrast and brilliance controls to their minimum values. 3.4.6 Adjust the control until there is a just noticeable difference in screen brightness thus ensuring the display of the lowest level echoes. This procedure establishes the brilliance level. 3.4.7 Examin