高强度聚焦超声温度场的有限差分模拟

本文在圆柱坐标中对高强度聚焦超声（HIFU）的声压和振速特性进行了理论研究，并结合Pennes生物热传导方程进行了高强度聚焦超声治疗温度场的仿真研究. 采用时域有限差分（FDTD）方法，求解Westervelt声波非线性传播的波动方程，并以水为传播媒质计算了凹面声源的焦点声压，进一步对Pennes生物热传导方程进行数值解析，模拟和绘制了超声波传播过程中焦域附近温度场，获得65℃以上的焦域的形状、大小和位置. 结果表明HIUF治疗中所形成的焦域近似圆柱体，其距离比几何焦点稍近. 本研究为HIFU实际应用中的
The properties of acoustic pressure and vibration velocity generated by high intensity focused ultrasound（HIFU） are theoretically studied in the cylindrical coordinate. Based on the Pennes bio-heat conduction equation，the distributions of the temperature field and temperature rising for HIFU are also simulated. By using the finite difference method in time domain（FDTD），the Westervelt nonlinear propagation wave equation is solved and the sound pressure of the focal area is calculated in water. By solving the Pennes equation，the temperature fields at various conditions are simulated，and the shape，size and position of the focal region with the temperature higher than 65 ℃ are obtained. The numerical results demonstrate that the focal region of the HIUF treatment is approximate to a tiny cylinder with the position slightly closer than the geometrical focusing radius. This study provides a theoretical basis for precise positioning and temperature control in the practical application of HIFU