A mechanistic journey in shock wave lithotripsy research

As a remarkable engineering innovation, shock wave lithotripsy (SWL) has revolutionized the treatment of kidney stone disease since 1980s with worldwide clinical acceptance. Over the past three decades, the long journey to understand the transient interaction of focused shock waves with kidney stones and soft tissues has propelled fundamental research at multiple fronts, including (1) the generation, propagation, and interaction of various stress waves inside the bulk stone materials, and surface acoustic waves associated with Mach stem formation at the stone boundary; (2) dynamic fracture and comminution processes in relation to lithotripter field characteristics; and (3) cavitation-induced stone surface erosion and vascular injury. In this talk, I will present illustrative examples to highlight chronologically the progressive understanding regarding the mechanisms of stone comminution and tissue injury, and how the acquired knowledge has influenced the technology evolution and clinical practice in SWL. I will also discuss how the fundamental concepts and techniques of SWL have been widely utilized in other therapeutic ultrasound and lithotripsy applications; and future perspectives, especially related to 3D cavitation detection and monitoring, as well as multi-spark shock wave generator development.