A New Acoustic Lens Design for Electromagnetic Shock Wave Lithotripters

The 3rd‐generation electromagnetic (EM) shock wave lithotripters often have narrow focal width and high peak pressure compared to the original Dornier HM‐3. In addition, the pressure waveform produced by a typical EM lithotripter has a secondary compressive wave following the tensile component that suppresses lithotripter pulse induced cavitation, which may impact negatively on stone comminution. These characteristic changes in the modern EM lithotripters may contribute in part to their reduced effectiveness observed clinically. To overcome these two drawbacks, we have designed a new acoustic lens for the Siemens Modularis EM lithotripter that produces an idealized pressure waveform similar to that of the HM‐3 with broad focal width and low peak pressure. At acoustic pulse energy of 53 mJ, the new lens design enlarges the −6 dB focal width of the Modularis by 47% while significantly reducing the second compressive wave in the lithotripter pulse throughout its focal plane. After 2000 shocks, in vitro commi...