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 + 620.179.16.004.15BS5724-3.26:1990 This British Standard, havi
2、ng been prepared under the directionof the Health Care Standards Policy Committee, waspublished under the authorityof the Board of BSI andcomes into effect on 29June1990 BSI 06-1999 The following BSI references relate to the work on this standard: Committee reference HCC/111 Draft for comment 87/527
3、77 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 Technical Committee HCC/111, upon which the following bodies were represented: British Institute of Radiology Coll
4、ege of Radiographers Department of Health Department of Trade and Industry (National Physical Laboratory) Electro-Medical Trade Association Limited Institute of Physical Sciences in Medicine (IPSM) Ministry of Defence Ophalmological Society of the United Kingdom Scottish Health Services Amendments i
5、ssued since publication Amd. No. Date of issue CommentsBS5724-3.26:1990 BSI 06-1999 i Contents Page Committees responsible Inside front cover Foreword 2 Section 1. General 1 Scope and object 1 2 Definitions 1 Section 2. Preliminary test and operating conditions 3 Preliminary test and operating condi
6、tions 3 Section 3. Declaration and measurement of parameters 4 Performance parameters 5 5 Resolution 5 6 DEAD ZONE 6 7 SLICE THICKNESS 6 8 DEPTHS OF PENETRATION 7 9 DISPLAYED DYNAMIC RANGE 7 10 MAGNIFICATION ERRORS 7 11 REGISTRATION ERROR 8 12 ACCURACY OF THE CALLIPER 8 13 Presentation of performanc
7、e parameters 10 Section 4. Requirements for TEST-OBJECTS 14 TEST-OBJECT design 11 Appendix A Tissue-mimicking material 12 Figure 1 Section through TEST-OBJECT CONFIGURATION 1 to determine AXIAL RESOLUTION, DEAD ZONE and DEPTHS OF PENETRATION when 2 MHz frequency 8 MHz 13 Figure 2 Section through the
8、 REFERENCE PLANE of TEST-OBJECT CONFIGURATION 2 to determine LATERAL RESOLUTION when 2 MHz frequency 8 MHz 14 Figure 3 Section in a plane perpendicular to the REFERENCE PLANE of TEST-OBJECT CONFIGURATION 3 to determine SLICE THICKNESS when 2 MHz frequency 8 MHz 15 Figure 4 Section through the REFERE
9、NCE PLANE of TEST-OBJECT CONFIGURATION 4 for the production of an ACOUSTIC GREY SCALE wedge when 2 MHz frequency 8 MHz 16 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
10、 8 MHz 17 Table 1 Specified values for the attenuation of sound in tissue-mimicking materials 11 Publications referred to Inside back coverBS5724-3.26:1990 ii BSI 06-1999 Foreword This Section of BS5724 has been prepared under the direction of the Health Care Standards Policy Committee. This British
11、 Standard complements BS5724 “Medical electrical equipment” Part2 “Particular requirements for safety” Section2.26 “Specification for ultrasonic medical diagnostic equipment” 1) , which will be identical with the corresponding international standard being prepared by the International Electrotechnic
12、al Commission (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-OBJE
13、CTS. In 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 writte
14、n in capitals. 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 B
15、ritish 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, pages1to 18, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendment
16、s incorporated. This will be indicated in the amendment table on the inside front cover. 1) In preparation.BS5724-3.26:1990 BSI 06-1999 1 Section 1. General 1 Scope and object 1.1 Scope This Section of BS5724 describes the performance parameters to be stated in documents accompanying an ULTRASONIC M
17、EDICAL DIAGNOSTIC EQUIPMENT as defined in2.31, together with methods for evaluating its performance using specified TEST-OBJECTS. This Section of BS5724 does not cover Doppler effect facilities of ULTRASONIC MEDICAL DIAGNOSTIC EQUIPMENT. 1.2 Object The object is to permit the direct comparison of UL
18、TRASONIC MEDICAL DIAGNOSTIC EQUIPMENT of different manufacture, and to standardize methods for the determination of compliance with the manufacturers declared performance. 2 Definitions For the purposes of this Section of this British Standard, the following definitions apply. 2.1 accuracy of the ca
19、lliper 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 accoustic grey scale an area of a TEST REGION, the position of which is identified in the TEST-OBJECT docu
20、mentation, that displays a wide range of grey scale levels 2.3 central magnification letter symbols: a cxand a cy ratio of the length of the image, in the OUTPUT DISPLAY PLANE, of a given feature of a TEST-OBJECT, determined when the centre of the image is located at the CENTRE OF THE FIELD OF VIEW,
21、 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 centre 2.4 centre of the field of view a point on the centreline of the TEST-OBJECT, which is situated near
22、est 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 at30% DARK THRESHOLD when approximately30% of the region is at the lowest displayable grey level 2.6 70 % dark threshold a TEST REGION is said to be at70% D
23、ARK 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 which is unequivocally displayed 2.8 displayed dynamic range the ratio of the amplitude of the maximum echo that
24、 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 when scanned by the ULTRASOUND IMAGING SYSTEM with the transducer held stationary against the TEST-OBJECT SCANNIN
25、G 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 PLANE representing an area of more than one TEST REGION 2.12 30 % light threshold a TEST REGION is said to be at30% L
26、IGHT 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 at70% LIGHT THRESHOLD when approximately 70% of the region is at the highest displayable grey level 2.14 local magnification letter symbols: a dxand a dy
27、BS5724-3.26:1990 2 BSI 06-1999 the ratio of the length of the image, in the 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 di
28、rection is either perpendicular to (subscriptx) or parallel to (subscript y) the central scan line of the image 2.15 magnification error letter symbols: V dxand V dy. the difference between the CENTRAL MAGNIFICATION and the LOCAL MAGNIFICATION at a particular point in the FIELD OF VIEW for a given o
29、rientation, expressed as a percentage of the CENTRAL MAGNIFICATION 2.16 maximum 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
30、be obtained under normal operating conditions 2.18 output display plane the 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 rotati
31、ng transducers and phased array sector scanners. 2.20 rectilinear scanning 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
32、. A-mode facilities linked to an imaging system would be placed in the category 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
33、of images of a wire in a TEST-OBJECT when referred to the TEST-OBJECT dimensions 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, perpendicula
34、r to the SCAN PLANE, at a stated depth, of the material of the TEST-OBJECT 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 in
35、serts within a TEST-OBJECT which is used for one or more performance measurements 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 ultr
36、asound mechanical oscillation consisting of local compression, and rarefaction of the material, the frequency of which is above20 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
37、 ultrasonic medical diagnostic equipment EQUIPMENT for the generation and application to PATIENTS of ULTRASOUND and intended for medical diagnostic investigation (hereafter referred to as EQUIPMENT)BS5724-3.26:1990 BSI 06-1999 3 Section 2. Preliminary test and operating conditions 3 Preliminary test
38、 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 repeated through slightly different orien
39、tations 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 angle of30 to this line (30 measureme
40、nt). 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 the control of gain, measurements sh
41、all 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 set up for scanning as recommended in t
42、he ACCOMPANYING DOCUMENTS. 3.3 Scanning gain 3.3.1 The scanning gain shall be set as described in3.3.2 to3.3.8. 3.3.2 Select initial settings according to3.2. 3.3.3 Scan TEST-OBJECT CONFIGURATION 1 (seeFigure 1) through TEST-OBJECT SCANNING SURFACE 1 in the REFERENCE PLANE. 3.3.4 Adjust all gain con
43、trols 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 visualized depth to that observed in the pe
44、nultimate 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 scale. 3.3.8 Record the resulting position
45、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 in3.4.2 to3.4.13. NOTEThe selection of scanning gain as describ
46、ed in3.3 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 (groupD), adjust all focus controls available to the user
47、that affect the screen focus so as to obtain the sharpest presentation of the image. 3.4.4 Scan TEST-OBJECT CONFIGURATION 4 (seeFigure 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 min
48、imum 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 Examine the image region designated as ACOUSTIC GREY SCALE in the TEST-OBJECT documentat
49、ion and, by adjusting the contrast controls, maximize the length of this region over which a brightness variation is visible. This procedure establishes the contrast setting. 3.4.8 Repeat the procedure given in3.4.6 and3.4.7 in sequence until both the brightness and contrast setting criteria are simultaneously met. 3.4.9 If these brightness and contrast settings are sigificantly different from those recorded in3.3.8 repeat the scanning gain setting by the procedure outlined in3.3 and then from3.4.2. 3.4.10 Record the final focus, brilliance and contrast sett
