The development of a passive acoustic device for monitoring the effectiveness of shockwave lithotripsy in real time

This paper reports how laboratory experiments and hydrocode simulations (of cavitation and shock wave propagation) have been used to generate a clinical device which can deliver real benefit to patients with kidney stones. Currently X-ray or ultrasound B-scan imaging are used to locate the stone and to check that it remains targeted at the focus of the lithotripter during treatment. Neither imaging method is particularly effective in allowing the efficacy of treatment to be judged during the treatment session. In this study, laboratory experiment and Computational Fluid Dynamics simulations of the complex interactions between the shock wave, the stone, and the human tissue, have been used to develop a new clinical device. This device, which has been tested in clinical trials, exploits the passive acoustic emissions generated by these interactions, to identify whether the stone remains in the focus, and to what extent the treatment has been successful.