Simulation of the therapeutic region during HIFU therapy

Prediction of the size, shape, and variation of the therapeutic region (TR) induced by HIFU has a great significance to HIFU treatment planning. In this study, the approximation of Westervelt formula for the nonlinear propagation of ultrasound and Pennes bio-heat transfer equation have been used along with the Finite Difference Time Domain (FDTD) method to calculate the temperature field. Then the therapeutic region based on the temperature distribution was analyzed. It was found that an increase of the exposure time and the TR temperature resulted in the appearance of the influence of tissue acoustic properties. It was also found that during the process of obtaining the same lesion size, the average input intensity and the exposure time express a certain relationship.