COMPARATIVE ANALYSIS AND VALIDATION OF ULTRASOUND DOSIMETRY METHODS FOR ADAPTABLE IN VITRO SONODYNAMIC THERAPY

Sonodynamic therapy (SDT) is a non-invasive oncological approach that uses low-intensity ultrasound to activate sonosensitizers, generating reactive oxygen species (ROS) to induce target cell death such as tumors. Since the delivered ultrasound dose depends heavily on vessel geometry and attenuation, current instrument settings can not accurately define true treatment conditions. This study aims to validate an adaptable in vitro ultrasound exposure platform using complementary direct and indirect (physical and chemical) dosimetry methods identified through a literature review, evaluating their principles, advantages, and limitations.

The custom system features a glass tank coupled to a 1 MHz therapeutic ultrasound transducer (ERA: 8 cm²), with engineered interchangeable adapters that standardize sample-to-transducer distance for multiwell plates and Petri dishes using degassed Milli-Q water as a coupling medium. Physical dosimetry was performed through hydrophone-based acoustic field mapping under continuous-wave irradiation (1 W/cm², 1 min). Chemical dosimetry using 0.2 M potassium iodide (KI) solution and Terephthalic acid (TA) under pulsed irradiation (20% duty cycle, 1 W/cm², 30 min) were employed to quantify cavitation-induced chemical activity and inertial cavitation thresholds.

The hydrophone peak-to-peak voltages ranged from 218 to 246 mV in the 96-well plate corresponding to the four central wells, whereas the Petri dish configuration values were between 260 to 400 mV in the central region. While TA showed a volume dependent precision (2 mL), KI dosimetry confirmed homogeneous acoustic energy distribution and consistent cavitation activity within the same region identified by hydrophone measurements. By bridging acoustic field characterization with cavitation assessment, this work provides a practical framework for more reliable characterization of SDT exposure conditions and establishes practical guidelines for selecting dosimetry methods according to specific experimental objectives, representing an important step toward experimental standardization and clinical translation of SDT. 

This work was supported by the Coordination for the Improvement of Higher Education Personnel(CAPES)-88887.992634/2024-00, National Council for Scientific and Technological Development(CNPq):  465360/2014-9,   440237/2021-1,  408468/2024-6,  408449/2024-1,  304470/2026-0;   São Paulo Research Foundation (FAPESP): 2013/07276-1,  2014/50857-8, 2025/26804-6.