APPLICATION OF UNDERWATER SHOCK-WAVE FOCUSING TO THE DEVELOPMENT OF EXTRACORPOREAL SHOCK-WAVE LITHOTRIPSY

This paper describes a summary of a research project for the developme nt of extracorporeal shock wave lithotripsy (ESWL), which has been car ried out, under close collaboration between the Shock Wave Research Ce nter of Tohoku University and the School of Medicine, Tohoku Universit y. The ESWL is a noninvasive clinical treatment of disintegrating huma n calculi and one of the most peaceful applications of shock waves. Un derwater spherical shock waves were generated by explosion of microexp losives. Characteristics of the underwater shock waves and of ultrasou nd focusing were studied by means of holographic interferometric flow visualization and polyvinyliden-difluoride (PVDF) pressure transducers . These focused pressures, when applied to clinical treatments, could effectively and noninvasively disintegrate urinary tract stones or gal lbladder stones. However, despite clincal success, tissue damage occur s during ESWL treatments, and the possible mechanism of tissue damage is briefly described.