Effect of intended shift in propagation direction of cavitation generation position on coagulation position in bubble-enhanced ultrasonic heating

Abstract

High-intensity focused ultrasound (HIFU) is a noninvasive cancer treatment that uses powerful focused ultrasound energy to coagulate tissue. However, due to its small focal region, this treatment is time-consuming. Therefore, we have focused on the heating effect of cavitation bubbles. The safe utilization of bubbles requires that they are consistently generated and maintained in the treatment area. In this study, the effects of the HIFU focal shift in the direction of ultrasound propagation on the bubble and coagulation regions were investigated by high-speed camera and ultrasound imaging. As a result, the appropriate focal shift of pulses that generates the bubbles prevented expansion of bubble regions and generated coagulation regions with good reproducibility near the treatment target.