ASA 124th Meeting New Orleans 1992 October

1aEA2. Piezoelectric electronically focused shock wave generator.

Sylvain Nachef

Technomed International S. A., Bron, France

INSERM unite 281, 151 Cours Albert Thomas, 69424 Lyon Cedex 03, France

Dominique Cathignol

Alain Birer

INSERM unite 281, Lyon, France

Recently, shock wave generators (electrohydraulic, electromagnetic, or piezoelectric) have become of common use for the treatment of renal calculi and gallstones. In all these generators, the focal zone is fixed. This is a major drawback since it is well known that the stones move according to the respiratory cycle. Consequently, the shock waves are not always well focused on the stone, which results in an increase of the duration of the treatment and the development of lesions in the neighboring tissues. To resolve this problem, a piezoelectric electronically focused shock wave generator has been designed. Measurements of the sound field produced in water by the first prototype of this novel generation of extracorporal lithotripters are presented, which clearly demonstrate the advantages of this type of focusing.