High power sources for ultrasound thermal therapy and shock wave lithotripsy

We present a summary of Inserm's experience with high power sources, which are necessary for ultrasound thermal therapy and lithotripsy. Moreover, generating high intensity pseudo‐continuous waveforms or high pressure pulses imposes different constraints on the transducer materials, specifically heat and mechanical stress. For thermal therapy, miniature piezoceramic transducers were used for interstitial, intratumoral, and endoluminal applicators. These probes operated at surface intensities up to 50 W/cm2 and generated elementary lesions in vivo within tens of seconds. Piezocomposite transducers were developed for large‐aperture, highly‐focused beams used in extracorporeal or intraoperative treatments. Focal intensities were 1000 W/cm2 or higher and up to 256 elements were utilized. Miniaturized piezocomposite transducers are currently being developed for dual‐mode imaging and therapy. For lithotripsy, piezoelectric shock wave generators were developed as alternatives to electrohydraulic or electromagnet...