Cavitation-enhanced high-intensity focused ultrasound treatment for cancer therapy

Cavitation has been known to have a potential to enhance HIFU treatment in a few ways. It can multiply the particle displacement by orders of magnitude and thereby enhance the mechanical effect (1) of ultrasound hugely and the in vivo thermal effect (2) significantly. It can even induce chemical effect (3) when its bubble collapses. We are developing a cavitation-enhanced HIFU therapy system by which the effects (2) and (3) are aimed to obtain. The higher priority was set on the effect (2), because combination with a certain drug may be needed for the effect (3), which can make the process for the approval more difficult. In vivo cavitation threshold can hugely vary on the conditions. It can be reduced by stabilized microbubbles and nanobubbles, nanodroplets, and certain chemicals. However, these are not assumed in combination with our system for the same reason above. Instead, an ultrasonic pulse at an extremely high-intensity in the order of 10 MPa with a duration in the order of 10 ms is used to generate cavitation, which is immediately followed by a typical HIFU burst to obtain the effect (2). The results from swine tests of our HIFU system will be shown in the presentation.