Interaction of high intensity focused ultrasound with biological materials

This work is motivated by possible medical applications of focused ultrasound in minimally invasive treatment of a variety of disorders. The mechanical and thermal effects caused by high-frequency ultrasound in different material systems are calculated using a finite element based program called PZflex. The pressure distributions generated by plane as well as focused ultrasound beams are presented. For the focused beam, the temperature distribution in the focal zone is also calculated. The results indicate that the heating efficiency of the ultrasound energy in the focal region depends on the exciting frequency and the geometry of the focal zone depends on the material being tested. At higher excitation energies, cavitation and nonlinear effects need to be included in the simulations. These effects are under current investigation.