Quantitative assessment of acoustic field characteristics in water by radial extracorporeal shockwave therapy

Radial extracorporeal shockwave therapy (rESWT) is a noninvasive medical technique that treats a range of musculoskeletal conditions. To understand its biological effects and develop personalized treatment plans, it is crucial to fully characterize the acoustic field that rESWT generates. This study presents a quantitative assessment of rESWT's acoustic field, achieved through experiments and simulations. The study measures the acoustic fields using a needle-type hydrophone under different machine settings and establishes and calibrates a computational model based on the experimental measurements. The study also determines the spatial distributions of peak pressure and energy flux density for different driving pressures. High-speed photography is used to visualize cavitation bubbles, which correspond to the negative pressure distribution. The study finds that the axial pressure distribution is similar to the acoustic radiation from an oscillating circular piston, whereas the radial pressure distribution cannot be described by acoustic radiation. Furthermore, the study develops a machine learning model that predicts positive pressure distributions for continuous driving pressure. Overall, this study expands our understanding of the acoustic fields generated by rESWT and provides quantitative information to explore underlying biological mechanisms and determine personalized treatment approaches.