[The Dornier lithotripter in a comparison. Measuring shockwave fields and fragmentation effects].

For all Dornier lithotripters, comparative shock wave field measurements performed by using a modern piezoelectric pvdf-shock wave measuring technique. The high temporal and spatial resolution of the pressure probe provides many details of the focusing field right up to the focal point. The maximum amplitudes, the axial and lateral pressure distribution around the focus, and their changes as a function of primary energy are presented. Focusing is influenced in particular by the geometry of the reflector, diffraction- and non-linear propagation effects. A comparison between incident shock energies on model calculi in vitro and the resulting fragmentation shows the relationship between focus energy and disintegration effect. For a given lithotripter with fixed electrical and geometrical parameters, the number of shocks needed for complete fragmentation of the model calculus is inversely proportional to the square of the capacitor voltage, and proportional to the volume of the model calculus.