1、 CENELEC ENxbL2bb 95 3404583 OLbL35L 035 M 61266 : 1995 Ultrasonics Hand-held probe Doppler foetal heartbeat detectors Performance requirements and methods of measurement and reporting The European Standard EN 61226 : 1995 has the status of a British Standard CENELEC ENmbL2bb 95 rn 3404583 03b3352 T
2、3L BS EN 61266 : 1996 This British Standard, having been prepared under the direction of the Electrotechnicai Sector Board, was published under the authority of the Standards Board and comes inta effect on 15 October 1995 O BSI 1995 Committees responsible for this British Standard The preparation of
3、 this British Standard was entrusted to Technical Committee EPU87, Uitrasonics, upon which the following bodies were represented: British Dental Association British Institute of Radiology British Medical Ultrasound Society British Society for Rheumatology Deparhnent of Health Department of lbde and
4、Industry (National Physical Laboratory) institut of Laryngology and Otology Institute of Physicai Sciences in Medicine Institution of Electrical Engineers Amendments issued since publication I Text afected The following BSI references relate to the work on this standard Committee reference EPL87 Dra
5、ft for comment 91/22890 DC ISBN O 580 24679 9 CENELEC ENxbLZbb 95 m 3404583 OLbL353 908 m BS EN 61266 : 1995 Contents Page Committees responsible Inside front cover National foreword 11 Foreword 2 Text of EN 61226 3 i CENELEC EN*bL2bb 95 m 3404583 OLbL354 844 BS EN 61266 : 1995 National foreword Thi
6、s British Standard has been prepared by EPU87 and is the English language version of EN 61266 : 1995 Ultrasonics - Hand-heid probe Doppler foetal heartbeat detectors - Perrrnance requirements and methods of measurement and reporting, published by the European Committee for Electrotechnical Standardi
7、zation (CENELEC). It is identical with IEC 1226 : 1994, published by the International Electrotechnical Commission (IEC). Cross-references Publication referred to EN 60601-1 1990 (IEC 601-1 : 1988) (IEC 1101 : 1991) EN 61101 : 1993 EN 61102 : 1993 (IEC 1102 : 1991) EN 61157 : 1994 (IEC 1157 : 1992)
8、EN 61161 : 1994 (IEC 1161 : 1992) IEC 866 : 1987 Corresponding British Standard BS 5724 Medica.! electrical equipment Part 1 : 1989 Generd requirements for safety BS EN 61101 : 1994 Specifkation for absolute cdibration of hydrophones using the planar scanning technique in the frequency range 0,5 MHz
9、 to 15 MHz BS EN 61102 : 1994 SpecGfication for measurement and chumternsation of ultmsonk fields using hydrophones in thefuenc;yrangeO.5MHzto 15MHz BS EN 61157 : 1995 Requirements for the - requirements for the performance of equipment; - requirements for the reporting of the performance of existin
10、g equipment; - requirements for the declaration by manufacturers in accompanying literature of aspects of the performance of equipment. This International Standard is applicable to ultrasonic Doppler foetal heartbeat detectors which generate a single ultrasound beam and consist of a hand-held probe
11、which is applied to the maternal abdomen to obtain information on foetal heart activity by means of the Doppler method using continuous wave (c.w.) or quasi-continuous wave ultrasound. This standard, however, currently does not cover the continuous monitoring deuices which generate more than one ult
12、rasound beam and are usually of the type utilising a similar principie of operation but using a flat probe strapped to the patient. This International Standard is not an equipment design standard. 2 Normative references The following normative documents contain provisions which, through reference in
13、 this text, constitute provisions of this International Standard. At the time of publication, 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 t
14、he most recent editions of the normative documents indicated below. Members of IEC and IS0 maintain registers of currently valid International Stand a rd s. I EC 60 1 -1 : 1 988, Medical electrical equipment - Part 7 : General requirements for safety IEC 854: 1986, Methods of measuring the performan
15、ce of ultrasonic pulse-echo diagnostic equipment IEC 866: 1987, Characteristics and calibration of hydrophones for operation in the frequency range 0,5 MHz to 75 MHz IEC 1101 : 1991, The absolute calibration of hydrophones using the planar scanning technique in the frequency range 0.5 MHz to 15 MHz
16、CENELEC EN*bLZbb 95 3404583 OLbL3bO 048 Page 6 EN 61266 : 1995 IEC 1 102: 1991. Measurement and characterisation of ultrasonic fields using hydrophones in the frequency range of 0,5 MHz to 15 MHz IEC 1157: 1992, Requirements for the declaration of the acoustic output of medical diagnostic ultrasonic
17、 equipment IEC 11 61 : 1992, Ultrasonic power measurement in liquids in the frequency range 0,5 MHz to 25 MHz 3 Definftlons For the purposes of this International Standard, the following definitions apply: 3.1 surface in order to maintain acoustic transmission. acoustic coupling medium: Material pla
18、ced between the probe and the body 3.2 vation of the output of a hydrophone placed in an acoustic field. acoustic working frequency: Frequency of an acoustic signal based on the obser- For the purposes of this International standard, the signal is analysed using the zero-crossing frequency technique
19、, see IEC 854. 3.4.1 of IEC 11021. 3.3 quasi-continuous lasting for many tens of cycles. contlnuous wave ultrasound: Ultrasonic oscillations which are either continuous or 3.4 Doppler frequency: Change in frequency of an ultrasound scattered wave caused by relative motion between the scatterer and t
20、he probe. it is the difference frequency between the transmitted and the received wave. 3.5 distance of 5 mm from the face of the probe. 3.6 of IEC 11 021. effective area of the ultrasonic ttansducer active element: -6 dB beam area at a Unit: millimetre squared, mm2 3.6 Doppler signal: Signal at the
21、 Doppler frequency. 3.7 equipment: Ultrasonic Doppler foetal heartbeat detector. 3.8 quoted by the designer or manufacturer. nominal acoustic working frequency: Value of the acoustic working frequency 3.9 output power: Time-average ultrasonic power radiated by an ultrasonic transducer into an approx
22、imately free field under specified conditions in a specified medium, preferably in water. 3.5 of IEC 11611. Symbol: P Unit: watt. W Page 7 EN 61266 : 1995 3.1 O overall sensitivity: Measure of the ability of an ultrasonic Doppler foetal heartbeat detector to detect, above the noise level, a Doppler
23、signal from a simulated point target (less than three wavelengths wide) of known target plane-wave reflection loss, moving at a specified velocity and placed at a specified distance from the probe. The overall sensitivity level, S, in decibels (dB) is determined from: S=A(d)+B+C where A(d) is the ta
24、rget plane-wave reflection loss (dB) for the target at a distance d from the probe; B is the two-way attenuation over the acoustic pathway (dB), including that of the acoustic attenuator(s), any coupling window and water path; C is the signal-to-noise ratio (dB). Symbol: S Unit: decibel. dB 3.1 1 pr
25、obe: An assembly, including the ultrasonic transducer element(s), which is dedicated to the transmission and reception of ultrasound energy. It may also include other components as necessary. 3.12 receiver unit: Part of the equipment which processes the ultrasonic signals from the probe to produce a
26、t least a Doppler signal in the audible frequency range. 3.13 signal output part: Part of the equipment not being an applied part, intended to deliver output signal voltages or currents to other equipment, for example, for display, recording or data processing. 2.1.19 Of IEC 601-11. NOTE - For an ul
27、trasonic Doppler foetal heartbeat detector, the signal output part is usually a terminal or connector at the output of the receiver unit which allows connection of an earphone, headphone, speaker or other audio equipment 3.14 spatial-peak temporal-peak acoustic pressure: Larger of the maximum positi
28、ve or modulus of the maximum negative instantaneous acoustic pressure in an acoustic field. 3.26, 3.27 and 3.50 of IEC 11021. Unit: pascal, Pa 3.15 target plane-wave reflection loss: Ratio (dB) of the acoustic pressure at a specified distance from a target, in the ultrasonic field 180“ back-reflecte
29、d from the target, to the acoustic pressure in the plane wave incident coaxially with the target axis of sym- metry and at the position of the target if the target were removed. Target plane-wave reflection loss is expressed as a positive number. Symbol: A Unit: decibel, dB Page 8 EN 61266 : 1995 3.
30、16 transmitter unit: Part of the equipment which generates a high-frequency continuous wave or quasi-continuous wave electrical signal for energising the probe. 4 List of symbols a= 44 = B= Ba = Bw = c= c= d= f= k= P= Pa = s= t= u, = ut = v, = v, = z= a= A= radius of a ball or rod target target plan
31、e-wave reflection loss (dB) at a distance d two-way attenuation (dB) over a total acoustic path two-way insertion loss (dB) of an acoustic attenuator two-way insertion loss (dB) of a coupling window signal-to-noise ratio (dB) speed of sound in a medium distance between a target and the face of an ul
32、trasonic transducer or probe ultrasonic frequency (= 27dh) circular wavenumber output power of an ultrasonic transducer audio output power overall sensitivity of an ultrasonic Doppler foetal heartbeat detector thickness of an acoustic window hydrophone or ultrasonic transducer peak-to-peak signal at
33、 the position of a target hydrophone or ultrasonic transducer peak-to-peak signal at a specified distance from a target r.m.s. Doppler signal r.m.s. noise Electrical impedance Amplitude attenuation coefficient of plane waves in a medium Ultrasonic wavelength 5 Configuration The equipment normally co
34、mprises the following modules (which may or may not be incorporated within the same housing). as shown in figure 1 : - probe; - transmitter unit; - receiver unit; - signal output part. CENELEC EN*b12bb 95 m 3404583 OLb13b3 57 m Page 9 EN 61266:1995 6 Performance 6.1 Acoustic working frequency The ac
35、oustic working frequency shall not deviate more than I15 % from the nominal acoustic working frequency value stated by the manufacturer in accordance with clause 10. Compliance is checked by measurement in accordance with the test method given in 8. I. 7 Safety The equipment shall comply with IEC 60
36、1-1 and any in the IEC 601-2-X series dealing with foetal heartbeat detectors. I 8 Tests All measurements shall be undertaken using degassed water at a temperature of 22 OC f 5 OC. 8.1 Acoustlc working frequency The acoustic working frequency of the equlpment shall be determined using the acoustic c
37、oupling method shown in figure 2. The hydrophone shall comply with IEC 866 as a class-B hydrophone. The active element of the hydrophone shall be positioned in the centre, and at least 5 cm from the side and bottom walls, of the water vessel. Acoustic absorbers shall be used to line the vessel in or
38、der to reduce stray reflections. The hydro- phone shall be aligned for maximum signal. If the equipment operates in true continuous wave mode then a frequency counter may be used for the determination of the acoustic worklng frequency. In this case, the amplifier may be omitted if the frequency coun
39、ter has sufficient sensitivity. The frequency counter used for this purpose shall have a flat frequency response range greater than 140 Yo of the nominal acoustic worklng frequency of the equipment. If the equipment operates in any other mode such as quasi-continuous or swept frequency mode, the aco
40、ustic worklng frequency shall be determined from the waveform detected by the hydrophone, using an oscilloscope and the zero-crossing method, see IEC 854. For multiple frequency equipment, acoustic working frequency shall be measured for each stated nominal acoustlc worklng frequency (see clause 10)
41、. For swept frequency equipment, acoustic working frequency shall be measured at the lower and upper frequencies of the swept frequency range (see clause 10). The overall accuracy of the measurement of the acoustlc working frequency shall be fl % at the 95 Yo confidence level. 8.2 Output power Outpu
42、t power shall be determined using a radiation force balance in accordance with IEC 1161 or using a hydrophone and spatially integrating the square of the acoustic pressure following the procedures given in IEC 1101 and IEC 1102. The overall uncer- CENELEC EN*blEbb 95 3404583 OLbL364 793 Page 10 EN 6
43、1266 : 1995 tainty of measurement of output power shall be better than I50 o/o or better than I4 mW, whichever is greater at the 95 Yo confidence level. If, however, the output power is such that the equipment does not comply with clause 6 of IEC 1157, the overall uncertainty of measurement of outpu
44、t power shall be better than Ie30 o/o at the 95 Yo confidence level. The calibration of the measuring instrument should be traceable to National Measurement Standards. 8.3 Spatial-peak temporal-peak acoustic pressure The spatlal-peak temporai-peak acoustic pressure shall be determined in the whole u
45、ltrasonic field using the test method in IEC 11 02, or its equivalent. The hydrophone shall conform to IEC 866 and IEC 1102. The hydrophone should be calibrated by reciprocity or planar scanning methods given in IEC 866 or IEC 11 01, or by any other method which has been shown to yield equivalent or
46、 better accuracy. Where appropriate, the calibration of the hydrophone should be traceable to National Measurement Standards. If the spatlal-peak temporal-peak acoustic pressure in the whole ultrasonic field occurs at a distance from the face of the probe less than 5 mm, then the spatial-peak tempor
47、al- peak acoustic pressure shall be determined in the pari of the field where the distance from the face of the probe is at least 5 mm. 8.4 Effective area of the ultrasonic transducer active element The effectlve area of the ultrasonic transducer actlve element shall be determined by scanning a hydr
48、ophone in a plane perpendicular to the direction of the ultrasound beam and at a distance of 5 mm from the face of the probe using the method specified in 8.1.5 of IEC 11 02. 8.5 Overall sensitivity The overall sensitivity shall be determined using the method described in 8.5.1 and 8.5.2 which is ai
49、med at simulating the actual conditions of use of the equipment. The uncer- tainties of the test methods (at the 67 o/o confidence level) should not exceed: - target reflection loss 13 dB; - reproducibility I3 dB. - overall accuracy I6 dB. The determination of the overall sensitivity shall be undertaken using a small vibrating target placed in the ultrasonic field generated by the probe. Figure 3 shows a block diagram which illustrates the basic concept of the test method. 8.5.1 Test equipment 8.5.1.1 Target reflector A small target reflector with a known tar
