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) treatment is a noninvasive cancer treatment that uses powerful focused ultrasound energy to coagulate tissue, but it has the problem of time-consuming treatment due to its small focal region. Therefore, we pay attention to the heating effect of cavitation bubbles. The safe use of bubbles in treatment requires that they be reliably generated and maintained in the treatment region. 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 imaging 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 position to be treated.