DETERMINATION OF THE DISINTEGRATIVE CAPACITY OF LITHOTRIPTORS USING AN INVITRO STONE MODEL

To determine the disintegrative capacity of lithotripters in vitro, we carried out trials using an easy-to-handle standardized stone model, non-susceptible.to artefacts. An artificial stone composed of dental cement and microspheres was positioned in a cone-formed wire net. Shock waves were applied under in-line ultrasound localization coupled by a waterbath containing tapwater. The number of shock waves necessary for complete fragmentation was determined as the value of the disintegrative capacity of a lithotripter and correlated with the generator voltage. The following parameters were studied: stone mass, generator voltage, shock wave frequency, temperature and gas content of the coupling water. With this stone model, the disintegrative capacity of two different electromagnetic shock waves sources was evaluated: Modulith SL 20 and Lithostar Plus Overhead-Module. The two most essential parameters are the maximal disintegrative capacity and the disintegrative range between maximal and minimal energy. Our standardized stone model proved to be a suitable means of investigating the actual effectiveness of a lithotripter in clinical routine.