Full‐wave modeling of lithotripter fields

Eckard Steiger
1998 Journal of the Acoustical Society of America  
The propagation of focused extracorporeal shock wave Iithotripter pressure pulses is considered. A computational modeling must account for the effects of diffraction, nonlinear steepening and generation and propagation of weak shock waves. Some commercial Iithotriptcrs are reflector focusing sys[ems, Therefore reflections at curved boundaries have to he considered. For specific interests are in the propagation through and the interaction with human tissue structures, refraction, absorption and
more » ... on, absorption and scattering must be includable. A full wave model based on a set of nonlinear acoustic time domain equations is applied. This system is discretized t o obtain a finite difference representation of broad bandwidth and low dispersive character. To enable an accurate shock wave computation an algorithm that increases the [emporal and spatial resolution adaptively is developed, Exemplary a reflector focusing lithotripter is modeled. The model is validated by comparison of computed wave profiles with measured ones, The measurements are performed using a fiber-optic probe hydrophonc. Excellent agreements show the method to provide an accurate and flexible tool for field predictions of complex devices. Characterizing parameters like -6dB focal regions and energy quantities can be obtained easily, too.
doi:10.1121/1.422859 fatcat:kob4l5vvgnb4jpsqgmxj5fzwzy