Cavitation micro-bubble behavior in ultrasound field for HIFU therapy enhancement

The incepted cavitation micro-bubbles at the target tissue are used to enhance tissue heating in High-Intensity Focused Ultrasound therapy. The control of the inertial cavitation is required to achieve the efficient tissue ablation. The high-intensity ultrasound is used to incept a cavitation, so that the duration time is short enough to prevent the tissue coagulation. The low-intensity ultrasound follows just after the high-intensity ultrasound to continuously drive the cavitating micro-bubbles and coagulate the tissue. Following the experiment, we simulate the focusing of ultrasounds through a mixture containing micro-bubbles with considering the size and number density distributions in space. The numerical simulation shows that the heating region coincides with the cavitation incepted region by high-intensity ultrasound where the micro-bubbles are remaining as cavitation nuclei. The numerical results elucidate well the experimental ones.