Medical ultrasonic standards at NPL

Preston, R C; Livett, A.J.

doi:10.1049/ip-a-1.1984.0036

Cited by 5 publications

(6 citation statements)

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“…There are various medical applications of ultrasound such as medical imaging (echocardiography) which mostly concern soft tissues. [2][3][4][5] Thus, it is of the great importance, either for the safety of the patients or for the understanding of the experimental results, the knowledge of the acoustic field output is necessary. 6,7 The power generated from ultrasonic transducer ranges from few milliwatts for diagnostic equipments to several watts for physiotherapy applications.…”

Section: Introductionmentioning

confidence: 99%

“…Absolute measurement techniques provide accurate reference information and the results of measurements are capable of being monitored over both short and long periods, forming the basis of objective in national and international comparison and assessment. 4,8 The time average ultrasonic power emitted by the source transducer is one of the key values taken into account. 9 According to both fundamental International Electrotechnical Commission (IEC) standards dealing with acoustic output of medical ultrasonic devices, that of diagnostic devices (IEC 61157) and that of therapeutic devices (IEC 61689), the ultrasonic power is to be measured and declared.…”

Section: Introductionmentioning

confidence: 99%

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Measurement of total ultrasonic power using thermal expansion and change in buoyancy of an absorbing target

Dubey

Kumar

Gupta

et al. 2014

Review of Scientific Instruments

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A compact and miniaturized high resolution capacitance dilatometer for measuring thermal expansion and magnetostriction Rev. Sci. Instrum. 83, 095102 (2012) The Radiation Force Balance (RFB) technique is well established and most widely used for the measurement of total ultrasonic power radiated by ultrasonic transducer. The technique is used as a primary standard for calibration of ultrasonic transducers with relatively fair uncertainty in the low power (below 1 W) regime. In this technique, uncertainty comparatively increases in the range of few watts wherein the effects such as thermal heating of the target, cavitations, and acoustic streaming dominate. In addition, error in the measurement of ultrasonic power is also caused due to movement of absorber at relatively high radiated force which occurs at high power level. In this article a new technique is proposed which does not measure the balance output during transducer energized state as done in RFB. It utilizes the change in buoyancy of the absorbing target due to local thermal heating. The linear thermal expansion of the target changes the apparent mass in water due to buoyancy change. This forms the basis for the measurement of ultrasonic power particularly in watts range. The proposed method comparatively reduces uncertainty caused by various ultrasonic effects that occur at high power such as overshoot due to momentum of target at higher radiated force. The functionality of the technique has been tested and compared with the existing internationally recommended RFB technique. © 2014 AIP Publishing LLC. [http://dx

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Measurement of total ultrasonic power using thermal expansion and change in buoyancy of an absorbing target

Dubey

Kumar

Gupta

et al. 2014

Review of Scientific Instruments

View full text Add to dashboard Cite

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“…The upper limit is determined by the attenuation of ultrasound that increases with an increase in frequency. [1][2][3][4][5] Measurement of ultrasonic power from a medical ultrasonic equipment is essential for the assessment of the performance or safety of that equipment. 5,6 The power generated from medical transducer ranges from a few milliwatts for diagnostic equipment to several watts for physiotherapy applications.…”

Section: Introductionmentioning

confidence: 99%

“…Absolute measurement techniques provide accurate reference information and the results of measurements are capable of being monitored over both short and long periods, forming the basis of objective in national and international comparison and assessment. 3 The time average ultrasonic power emitted by the source transducer is one of the key values taken into account. 11 According to both fundamental International Electrotechnical Commission ͑IEC͒ standards dealing with acoustic output of medical ultrasonic devices, that of diagnostic devices ͑IEC 61157͒ ͑Ref.…”

Section: Introductionmentioning

confidence: 99%

Primary measurement of total ultrasonic power with improved accuracy in rf voltage measurement

Dubey

Kumar

et al. 2010

Review of Scientific Instruments

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Out of the various existing ultrasonic power measurement techniques, the radiation force balance method using microbalance is most widely used in low power ͑below 1 W͒ regime. The major source of uncertainty associated with this technique is the error in ac voltage measurement applied to the transducer for the generation of ultrasonic waves. The sources that deteriorate the ac voltage measurement accuracy include cable length and impedance mismatch. We introduce a new differential peak to peak measurement approach to reduce the ac voltage measurement error. The method holds the average peak amplitude of each polarity. Ultralow offset difference amplifier is used to measure peak to peak voltage. The method is insensitive to the variations in the dc offset of the source. The functionality of this method has been tested and compared with the conventional rf voltage measurement method. The output of this proposed technique is dc, which can be measured with an error of less than 0.1%.

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“…Assessment of the performance of flowmeter probes has been described by Preston and Livett [1]. However, a performance standard has recently been drawn up by a Special Working Group of the EEC -CRM/CREST Committee on Medical and Public Health Research, which is organising a concerted action on blood flow measurements by ultrasound [2].…”

Section: Introductionmentioning

confidence: 99%

An electronic Doppler signal generator for assessing continuous-wave ultrasonic Doppler flowmeters

Smallwood

Dixon

1986

IEE Proc. A Phys. Sci. Meas. Instrum. Manage. Educ. Rev. UK

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Medical ultrasonic standards at NPL

Cited by 5 publications

References 0 publications

Measurement of total ultrasonic power using thermal expansion and change in buoyancy of an absorbing target

Measurement of total ultrasonic power using thermal expansion and change in buoyancy of an absorbing target

Primary measurement of total ultrasonic power with improved accuracy in rf voltage measurement

An electronic Doppler signal generator for assessing continuous-wave ultrasonic Doppler flowmeters

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