The effects of wave front distortion in ESWL

The effects of phase aberration in extracorporeal shock-wave lithotripsy (ESWL) were investigated. Some patients undergoing these treatments experience focal damage to normal soft tissue in areas away from the intended treatment site. The authors hypothesized that some of the reported soft tissue damage may be caused by mislocation of the focus due to phase aberration of the shock wave in fat layers. This hypothesis was tested by measuring acoustic pressure distributions under four propagational conditions involving the type of medium and type of aberrating layer. Shock-wave pressure distributions were measured in water and in an attenuating medium. A very durable hydrophone was used and shown to survive more than 6000 shocks. The properties of the attenuating medium, a description of the hydrophone, and the observed effects of phase aberration in shock-wave propagation are reported