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Pressure waveforms in the acoustic field generated by a Dornier (HM3) shock-wave lithotripter have been measured using a bilaminar shielded PVDF membrane hydrophone in water. Using these waveforms, values of the peak-positive (p+) and peak-negative pressure (p-) at various positions in the field have been estimated. At the focus, p+ is 38.6 MPa (standard(More)
Increasingly, it is recognised that diagnostic ultrasound is capable of causing temperature rises sufficient to damage tissue. Predictions of this heating are often based on simplified models of both the in vivo conditions and the relevant physical effects. Few measurements have been made to verify these predictions, however, particularly for the tightly(More)
  • D R Bacon
  • 1988
A primary calibration method for ultrasonic hydrophones which uses a Michelson interferometer to determine the particle displacement in an ultrasonic field is discussed. The acoustic pressure is derived from this measurement and used to determine the free-field sensitivity of a hydrophone in the frequency range 0.5-15 MHz. The random uncertainty of the(More)
A method is described for comparing the sensitivity of two hydrophones over the frequency range 1-15 MHz. This technique forms the basis for the dissemination of national ultrasonic standards in the U.K. over this frequency range. A reference hydrophone is placed in an ultrasonic field and then the device being calibrated is substituted and the two output(More)
  • D R Bacon
  • 1984
A simple theoretical model of the non-linear propagation of pulsed focused acoustic beams is described. It enables the distortion of the peak cycle of the pulse to be calculated from a few experimentally measured parameters. The model is discussed, and justified for application to the fields from medical ultrasonic diagnostic equipment. It is particularly(More)
The heating of tissues by the absorption of ultrasound is an important safety consideration in the use of diagnostic ultrasound. This paper shows that models of ultrasonic heating for this situation need to take account of nonlinear propagation. Measurements were made of the temperature rise in a sample of tissue-mimicking gel, caused by the application of(More)
Non-linear propagation models are required to predict the fields from medical ultrasonic equipment, particularly diagnostic devices and lithotripters. This need arises because of the requirement to know the safety and effectiveness of these instruments. Several theoretical models have been developed to take account of non-linear propagation as well as(More)
The results of an interlaboratory comparison of hydrophone calibration techniques in the frequency range 1-10 MHz are reported. Two membrane hydrophones were calculated to six laboratories, and each laboratory determined the end-of-cable loaded sensitivities using their normal calibration methods; these included optical interferometry, planar scanning,(More)