Dual-frequency High Intensity Focused Ultrasound (HIFU) Accelerating Therapy.

By cutting a spherical focused transducer into two coaxial and confocal transducer elements, a confocal complex transducer used in dual-frequency HIFU system was obtained. The lesion induced by dual-frequency HIFU in freshly excised porcine livers were obviously larger than that induced by conventional single-frequency HIFU at the same exposure conditions. The experiment results have also shown that injecting ultrasound contrast agents to the tissue or selecting appropriate difference frequency could further improve the lesioning effect. The dual-frequency HIFU would bring a new approach to accelerate ablating large tumor with HIFU and also provide a new method to miniaturize the conventional HIFU apparatus.