Modeling a conical applicator for high intensity focused ultrasound with the finite element method

The high-intensity focused ultrasound (HIFU) has shown positive results in the treatment of prostate cancer and its possible application in neurodegenerative diseases. This paper describes the design of a HIFU applicator with a conical geometry, for modeling the software COMSOL® (COMSOL Inc., Burlington, MA) was used, which bases its operation on the finite element method (FEM). The equations that govern the phenomenon were used to optimize the dimensions of the applicator and their use in the application surface. The design condition to be met is that the applicator should not alter the focus and acoustic field generated by the transducer source of ultrasound. The designed model allows that the system does not depend on a water container for the application of HIFU, reducing the dimensions and facilitating interaction with the system. It was obtained a design where the conical applicator has a radius at the apex of 5.2 mm, a radius at the base of 11.5 mm, a thickness of 2 mm walls, an operating frequency of 2 MHz and a focus of 20 mm operation. Water was considered as a means of propagation between the application surface and the applicator.