Approximate Analytical Solution for Tissue Temperature Distribution in High-Intensity Focused Ultrasound

An approximate analytical solution for tissue temperature distribution in high-intensity focused ultrasound (HIFU) is obtained in this work. Based on variable separation method (VSM), the solution is performed to solve the simplified bioheat transfer equation (BHTE). Lack of enough boundary conditions; the parameters in this analytic solution are estimated using the temperature data calculated by finite element method (FEM) with nonlinear least square algorithm. The absolute root mean square error (RMSE) of temperature is 0.21degC and 0.22degC for two strategies, respectively. Feasibility and accuracy of the analytical solution are verified by comparison with FEM for transient temperature response in a longer time domain. The average deviation of temperature is about 0.35degC. So this analytic solution is suitable to calculate spatiotemporal temperature distribution in HIFU treatment, and it is quite useful to the treatment planning.