THE PERFORMANCE OF DIFFERENT PRESSURE PULSE GENERATORS FOR EXTRACORPOREAL LITHOTRIPSY - A COMPARISON BASED ON COMMERCIAL LITHOTRIPTERS FOR KIDNEY-STONES

By using needle hydrophones and a PC-controlled experimental set-up, the acoustic output of 10 commercial extracorporeal shock-wave lithotripters has been measured. The pressure field was measured in the focus, along the beam axis, in the focal plane and ''at the skin level'' (a plane orthogonal to the beam axis, 5 cm backward from the focus, assumed as the entrance site of the pressure pulse into the patient's body). The set of tested instruments included the three technologies nowadays in use to generate the pressure pulse, namely electrohydraulic, electromagnetic and piezoelectric. Notwithstanding large intra-technology variability, the results indicate that electrohydraulic and electromagnetic generators can provide comparable performances. Piezoelectric generators produced pressure pulses with less energy than the others. Possible implications of the experimental results on treatment safety and effectiveness of kidney stone destruction are discussed.