In-vitro modelling and measurement of focused ultrasound fields for use in sonodynamic therapy

Abstract Sonodynamic therapy, which combines lowintensity ultrasound with sonosensitizers, shows promising anti-cancer effects, yet its underlying mechanisms remain incompletely understood. To support systematic in vitro studies, we developed and characterized an ultrasound setup designed to expose cells to well-defined and reproducible conditions. The setup includes a water tank, a sample holder, and absorbing structures to minimize stationary waves. Hydrophone measurements were conducted to assess the ultrasound pressure field, and finite element method (FEM) simulations were used to complement these measurements. The simulations allow for insights into power and intensity distributions that are challenging to measure directly. Results showed good agreement between measured and simulated pressures, although discrepancies of up to 20% were observed in ring patterns present in the simulation, but absent in the measurements. The study highlights the importance of simulations for optimizing experimental design and interpreting measurement artifacts, particularly those created by the hydrophone itself.