Experiment using water tank model for ultrasonic pulse propagation in extracorporeal shock wave lithotripsy and its numerical simulation

摘要

The extracorporeal shock wave lithotripsy has come into wide use rapidly owing to its advantage of non-invasiveness. However, as for the shock wave propagation in the human body in relation to practical lithotripsy, reports of numerical simulation based on models conforming to a practical situation are few. As a basic research for this subject, we have measured the excited pulse wave forms by using a water tank model based on a practical lithotriptor and made numerical simulation on the basis of these measured data by using the FD-TD method to compare the results with those of experiments. It came out that the simulated results become unrealistic if the measured excitation pulse wave forms are used directly. To examine the cause, several methods for providing excitation functions were tested. Then, it was found that practical results similar to those of experiment can be obtained, only if suppressed amplitude pulses far smaller than the real measured ones are supplied for excitation functions.