Pressure Distribution for Piezoelectric Extracorporeal Shock Wave Lithotripsy

The objective of this study is to develop a safer and more effective extracorporeal shock wave lithotripter. The first stage of the study shows the sound pressure field of the shock wave made by an ECHOLITH ESL-500A. The sound pressure distribution is in a ring configuration on a 60 mm plane in front of the focal plane. As the plane approaches the focal plane, the sound pressure relatively increases at the cross point with the axis of the transducer and decreases at the ring. The focal zone is 2.5 mm×16.1 mm at 60 V driving voltage and 1.8 mm×14.2 mm at "INTENSITY 2." In the next stage we propose a method for changing the field by electronic driving control of each piezoceramic element for effective therapy. The focal zone can be changed from 3.1 mm×19.1 mm to 3.9 mm×32.4 mm at 60 V driving voltage with this method. These focal zones are calculated by means of computer simulation.