Full‐wave modeling of lithotripter fields
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
... 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.