403 The Behavior of Ultrasound Propagation in Lithotrity
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In the clinical field, focusing phenomenon of ultrasound is widely applied today, such as Extracorporeal Shock Wave Lithotripsy (ESWL), ultrasonography, and hyperthermia. Although ESWL has been used routinely for the treatment of urolithiasis since 1980's, it also causes acute renal injury by violent collapse of cavitation. To the contrary, the collapse of cavitation by ultrasound focusing can be used for noninvasive lithotrity. It is essential to take a real understanding of the behavior of propagation on ultrasound focusing and the dynamics of cavitation in ultrasound field. To observe focusing phenomenon and cavitation collapse, we made experimental apparatus using piezo-transducer, and numerically simulated the propagation of ultrasound focusing. We observe that ultrasound is plane wave at first, then it gradually takes on nonlinear behavior, and at focus it turns shock wave.
