Clinicians have no yardstick to help them choose the most efficient li
thotriptor. Their leading priority is a system allowing complete disin
tegration of the stone with the minimum number of shocks and a low re-
treatment rate. One of the prerequisites of this system is a powerful
shock wave generator. ''Power'' is as yet ill defined in lithotripsy.
Therefore clinicians' choice depends upon other factors. Acoustic outp
ut measurements were recorded on 3 commercial lithotriptors representi
ng the 3 main shock wave generating systems. These were the Dornier MP
L 9000 (standard and X-155 electrodes), the Siemens (Lithostar, Lithos
tar Plus and System C) and the Wolf Piezolith 2300. The shock wave mea
surements were correlated to the capability of the lithotriptors to di
sintegrate standard stone models in vitro. Two factors were identified
. The pulse intensity integral in the focus and the size of the focal
zone proved to be the most important factors to assess and compare the
efficacy or ''power'' of different lithotriptors. Together they can h
elp clinicians to identify and choose the most efficient shock wave ge
nerating systems.