1、STD-BSI BS EN bL84b-ENGL 1991 Rs LL24bb7 074b478 547 M BRITISH STANDARD Ultrasonics - Pressure pulse lithotripters - Characteristics of fields The European Standard EN 618461998 has the status of a British Standard ICs 11.040.60 BS EN 61846:1999 IEC 61846:1998 NO COPYING WITHOUT BSI PERMISSION EXCEP
2、T AS PERMITTED BY COPYRIGHT LAW STD-BSI BS EN bL84b-ENGL direction of the Elecrotechnical Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 January 1999 Amd. No. O BSI 01-1999 BS EN 61846:1999 Date Text affected National foreword This British
3、Standard is the English language version of EN 61846:1998. It is identical with IEC 618461998. The UK participation in its preparation was entrusted to Technical Committee EPU87, Ultrasonics, which has the responsibility to: - aid enquirers to understand the text; - present to the responsible intern
4、ationalhropean committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; - monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this committee can be obtained on request to its
5、secI - lithotripsy equipment producing focused mechanical energy. This International Standard does not apply to percutaneous and laser lithotripsy equipment. This International Standard specifies - measurable parameters which could be used in the declaration of the acoustic output of extracorporeal
6、lithotripsy equipment, - methods of measurement and characterization of the pressure field generated by lithotripsy equipment. NOTE - The parameters defined in this International Standard do not - at the present time - allow quantitative statements to be made about effectiveness and possible hazard.
7、 In particular, it is not possible to make a statement about the limits for these effects. While this particular standard has been developed for equipment intended for use in lithotripsy, it has been developed such that, as long as no other specific standards are available to be used for other medic
8、al applications of therapeutic extracorporeal pressure pulse equipment, this standard may be used as a guideline. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of pu
9、blication, the editions indicated were valid. All normative documents are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. Members of IEC
10、and IS0 maintain registers of currently valid International Standards. IEC 60050(801):1994, International Electrotechnical Vocabulary (IEV) - Chapter 801: Acoustics and electroacoustics IEC 60866: 1987, Characteristics and calibration of hydrophones for operation in the frequency range 0,s MHz to 15
11、 MHz IEC 61 102:1991, Measurement and characterisation of ultrasonic fields using hydrophones in the frequency range 0,s MHz to 15 MHz STD-BSI BS EN 6184b-ENGL 1379 !W Lb24667 074b505 507 Page 6 EN 61846:1998 3 Definitions For the purpose of this International Standard, the following definitions app
12、ly. 3.1 acoustic pulse energy 3.1.1 derived acoustic pulse energy spatial integral of the derived pulse-intensity integral over a circular cross-sectional area of radius R in the x-y plane which contains the focus Symbol: ER Unit: joule, J 3.1.2 derived focal acoustic pulse energy spatial integral o
13、f the derived pulse-intensity integral over the focal cross-sectional area Symbol: Ef Unit: joule, J NOTE - This definition may overestimate E if the aperture of the pressure pulse generator is large. 3.2 beam axis line passing through the geometric centre of the aperture of the pressure pulse gener
14、ator and the focur NOTE - This line is taken as the zaxis. See 6.1 and clause 7. 3.3 compressional pulse duration time interval beginning at the first time the instantaneous acoustic pressure exceeds 50 Oh of the peak-positive acoustic pressure and ending at the next time the instantaneous acoustic
15、pressure has that value (see figure C.l) Symbol: FWHM+ Unit: second, s NOTE - The subscript FWHM stands for full width, half maximum. 3.4 derived pulse-intensity integral time integral of the instantaneous intensity at a particular point in a pressure pulse field over the pressure pulse waveform (se
16、e 3.31 of IEC 61 102) Symbol: PI/ Unit: joule per metre squared, J/m2 3.5 end-of-cable loaded sensitivity of a hydrophone ratio of the voltage at the end of any integral cable or connector of a hydrophone, when connected to a specified electrical input impedance, to the instantaneous acoustic pressu
17、re in the undisturbed free field of a plane wave in the position of the acoustic centre of the hydrophone if the hydrophone were removed (see 3.14 of IEC 61 102) Symbol: ML Unit: voit per pascal, V Pa- STD-BSI BS EN bL89b-ENGL. 1777 I Lb29bbS 079b50b 443 I Page 7 EN 61846:1998 3.6 focal cross-sectio
18、nal area area of the peak-compressional acoustic pressure contour which is -6 dB relative to the value at the focus and is in the plane, perpendicular to the beam axis, which contains the focus Symbol: Af Unit: metre squared, m2 3.7 focal extent shortest distance along the z axis that connects point
19、s on the -6 dB contour of peak-positive acoustic pressure in the x-z plane on either side of the focus Symbol: f Unit: metre, m 3.8 focal volume volume in space contained within the surface defined by the -6 dB (relative to the value at the focus) peak-compressional acoustic pressure contours measur
20、ed around the focus Symbol: V, Unit: metre cubed, m3 NOTE - It is difficult to measure -6 dB points throughout the volume around the focus. It is reasonable in practice to approximate the focal volume from measurements taken in three orthogonal directions: the beam axis (2 axis); the direction of ma
21、ximum beam diameter (x axis); the axis perpendicular to the x axis (y axis). 3.9 focal width, maximum maximum width of the -6 dB contour of p+ around the focus in the x-y plane which contains the focus Symbol: fx Unit: metre, m 3.10 focal width, orthogonal width of the -6 dB contour of p+ around the
22、 focus, in the x-y plane which contains the focus, in the direction perpendicular to fx Symbol: fy Unit: metre, m 3.1 1 focus location in the pressure pulse field of the maximum peak-positive acoustic pressure 3.12 hydrophone transducer that produces electrical signals in response to waterborne acou
23、stic signals IEV 801 -32-261 (see also IEC 60866) 3.13 instantaneous acoustic pressure pressure minus the ambient pressure at a particular instant in time and at a particular point in an acoustic field (see also 801-21-19 of IEC 60050(801) Symbol: p Unit: pascal, Pa 3.14 instantaneous intensity acou
24、stic energy transmitted per unit time in the direction of acoustic wave propagation per unit area normal to this direction at a particular instant in time and at a particular point in an acoustic field For measurement purposes referred to in this standard, where far-field conditions may be assumed,
25、the instantaneous intensity, I, is expressed as: Z where p is the instantaneous acoustic pressure; Z is the characteristic acoustic impedance of the medium. (See also 3.21 of IEC 61 102.) Symbol: I Unit: watt per metre squared, W/m2 3.15 lithotripsy equipment device for disintegrating calculi and ot
26、her concretions within the body NOTE - Known applications include renal stones, gallstones, pancreatic duct stones, salivary stones, orthopaedic pain and calcification in tendons. 3.16 peak-negative acoustic pressure, peak-rarefactional acoustic pressure maximum of the modulus of the rarefactional a
27、coustic pressure at any spatial location in the pressure pulse field (see 3.26 of IEC 61 102) Symbol: p- Unit: pascal, Pa 3.17 peak-positive acoustic pressure, peak-compressional acoustic pressure maximum compressional acoustic pressure at any spatial location in the pressure pulse field (see 3.27 o
28、f IEC 61 102) Symbol: p+ Unit: pascal, Pa 3.18 pressure pulse acoustic wave emitted by the lithotripsy equipment STD-BSI BS EN b1bLlb-ENGL 1999 I 1b24bb9 07Llb508 2Lb I Page 9 EN 61846:1998 ,. 3.19 pressure pulse waveform temporal waveform of the instantaneous acoustic pressure at a specified positi
29、on in a pressure pulse field and displayed over a period sufficiently long to include all significant acoustic information in the pressure pulse 3.20 pulse-pressure-squared integral time integral of the square of the instantaneous acoustic pressure over the pressure pulse waveform Symbol: pi Unit: p
30、ascal squared seconds 3.21 rise time at the focus, time taken for the instantaneous acoustic pressure to increase from 10 % to 90 % of the peak-positive acoustic pressure (see figure C.l) Symbol: f, Unit: second, s 3.22 target location location in space where the manufacturer intends the user to loc
31、ate the calculi 3.23 temporal integration limits 3.23.1 positive temporal integration limits times between which the positive acoustic pressure first exceeds 10 % of its maximum value and the first time it reduces below 10 % of its maximum value Symbol: p Unit: seconds 3.23.2 total temporal integrat
32、ion limits times between which the absolute value (modulus) of pressure pulse waveform first exceeds 10 % of its maximum value and the last time it reduces below 10 % of its maximum value Symbol: T Unit: seconds I 4 List of symbols E,: ER: f,: fy: f,: I: ML: P: p-: P+Z Pi: PII: FWHM+: Tp: TT: 4: Z:
33、focal cross-sectional area derived focal acoustic pulse energy derived acoustic pulse energy focal width, maximum focal width, orthogonal focal extent instantaneous intensity end-of-cable loaded sensitivity of the hydrophone instantaneous acoustic pressure peak-negative acoustic pressure peak-positi
34、ve acoustic pressure pulse-pressure-squared integral derived pulse-intensity integral rise time compressional pulse duration positive temporal integration limits total temporal integration limits focal volume characteristic acoustic impedance of the medium 5 Conditions of measurement Measurements sh
35、all be performed in a situation approximating conditions of actual operation. Parameters to be considered include: - pressure pulse generator drive level; - rate of pressure pulse release; - ambient temperature; - electrical conductivity of water in the measuring tank; - temperature and oxygen conte
36、nt of water in the measuring tank. The values of these parameters at which the measurements are made shall be noted. Degassed water (see annex C) at 20 OC to 40 OC should be used in the measuring tank (test chamber) which shall be large enough to allow the measurement environment to approximate free
37、-field conditions. If degassed water is not used, great care shall be taken to ensure that bubbles do not collect on the hydrophone nor anywhere in the beam path. STD-BSI BS EM bLBLib-ENGL 1779 8 lb2Libb7 07Lib510 97Y O Page 11 EN 61846:1998 The conductivity of the water shall be suitable for the hy
38、drophone being used. The calibration of the hydrophone shall be known at the temperature of the water in the measuring tank. 6 Test equipment 6.1 Test chamber The test chamber shall be a water tank constructed in a form that can be securely fixed to the pressure pulse generator so that the acoustic
39、output from the pressure pulse generator is coupled into a volume of water. The chamber shall be sufficiently large to allow the expected position of the focus to be several centimetres away from any reflective boundary, in particular the water surface. The distance between the focus and reflective
40、boundaries shall be chosen such that no spurious or multiple reflections of the pressure pulse interfere with the measurements. There shall be a suitable mechanical holder for the hydrophone which shall be mounted on a coordinate positioning system to allow adjustment and measurement of the position
41、 of the hydrophone in three orthogonal directions relative to the focus. One axis (z axis) of the co-ordinate positioning system shall be collinear with the beam axis. The relative position of the hydrophone shall be measurable with a precision of 0,5 mm or better. Care shall be taken to ensure that
42、 the coupling membranes do not influence the measurements. The coupling media shall be as specified by the manufacturer. 6.2 Hydrophone The hydrophone shall have characteristics complying with IEC 60866. For the purposes of this standard, two classes of hydrophones are specified: - a focus hydrophon
43、e; - a field hydrophone. 6.2.1 Focus hydrophone The focus hydrophone shall be equivalent to a single-film piezopolymer spot-poled membrane type not thicker than 25 pm (see annex C and IEC 61 102). Calibration shall be performed in the frequency range 0,5 MHz to 15 MHz in accordance with the requirem
44、ents of IEC 60866. The frequency response shall not vary by more than f3 dB over the calibrated frequency range. The effective diameter of the hydrophone shall be not greater than 1,0 mm, it should be as small as possible and its value shall be stated. NOTE - The lower frequency limit of current hyd
45、rophone calibration according to IEC 60866 and IEC 61102 is 0,5 MHz. It would be desirable, however, for the purpose of the measurements described here to extend the hydrophone calibration to lower frequencies, at least to 0,2 MHz. 6.2.2 Field hydrophone The field hydrophone shall have a robust cons
46、truction and shall have a response which does not vary by more than i3 dB per octave over the frequency range from 0,5 MHz to 15 MHz. The effective diameter of the hydrophone shall be not greater than 1,0 mm, it should be as small as possible and its value shall be stated. Page 12 EN 61846:1998 The
47、sensitivity of the hydrophone shall not vary by more than f10 % over the course of the measurements. NOTE - Two different hydrophone. are permitted because many of those suitable for measurements at the focue are very fragile. A more robust, less highly specified device is therefore permitted for ge
48、neral field measurements. Care is to be taken, when selecting a field hydrophone to select a type which will provide the needed linearity and negative acoustic pressure readings of the high pressures encountered. 6.3 Voltage measurement 6.3.1 Oscilloscope or transient recorder The device used to obs
49、erve and measure the hydrophone output signal shall be appropriate for the purpose, its frequency response and input capacitance and resistive impedance shall be reported. A digital oscilloscope with a sampling frequency greater than 100 MHz is the preferred option, although a transient recorder and digital storage for subsequent computer display may be satisfactory. The end-of-cable loaded sensitivity of the hydrophone shall be determined as specified in 5.1.2 of IEC 61 102, this value shall then be used to calculate the incident acoustic pressures from the observed hydr
