Comparison of three different transducer concepts for acoustic bladder volume measurements

In a preceding study the importance of noninvasive bladder volume measurements was addressed, and a new technique to measure the bladder volume on the basis of nonlinear ultrasound wave propagation was validated. It was shown that the harmonic level generated at the posterior bladder wall increases for larger bladder volumes. The objective of this study is to design an optimal transducer to implement this approach. For this purpose, three different transducer concepts, i.e. a multi-layer transducer, a broadband piezo-composite transducer and a multi-element transducer, were mutually compared using calibrated hydrophone measurements in water and pulse-echo measurements on a bladder test phantom. The effects of an additional acoustic lens on the beamwidth and generated peak pressures were also considered.