Piezoelectric shock wave generator with electronic focusing

Electrohydraulic, electromagnetic and piezoelectric shock wave generators used in the treatment of renal calculi and gallstones have their focal zone determined by their geometrical parameters. A piezoelectric shock wave generator with electronic focalization is proposed. The system is composed of a bidimensional array of 25 piezoelectric independent transducers arranged in a spherical shell 10 cm in diameter. The electronic circuitry of the system includes 25 pulsers. The interdelay of each channel can be adjusted between 10 ns and 100 mu s by steps of 10 ns. The pressure at the surface of the shell was 22*10/sup 5/ Pa. The focal point can be electronically moved in an ellipsoidal zone 3 cm in diameter and 4 cm long. These values are large enough to follow the displacement of the renal calculus during respiration.<>