非均匀组织医学超声非线性传播仿真  

Simulation of nonlinear ultrasound propagation in heterogeneous tissue

作　　者：周浩[1] 郑音飞[1] 

机构地区：[1]浙江大学生物医学工程教育部重点实验室,浙江杭州310027

出　　处：《浙江大学学报（工学版）》2016年第3期574-579,共6页Journal of Zhejiang University：Engineering Science

基　　金：中央高校基本科研业务费专项资金资助项目(2015FZA5019;2016FZA5015)

摘　　要：为了实现仿真医学超声波在非均匀组织中的传播过程,建立超声非线性传播计算模型.由软组织中一阶非线性波动方程推导得出"声压-质点振动速度"耦合超声非线性波动方程以降低求解复杂度.采用k空间方法对非线性波动方程组求解,在保证数值计算精度的同时降低计算的内存占用量和计算时间.通过与一维问题的解析解和二维问题的时域有限差分(FDTD)求解结果对比,验证所述模型的精度.在空间采样率为声波波长的1/9、Courant-Friedrichs-Lewy(CFL)数为0.3的情况下,所述模型的平方误差为0.012 5%,而时域有限差分方法(FDTD)的平方误差为42.5%.利用体腹壁组织数字模型,进行医学超声谐波成像仿真,验证谐波成像较基波成像能够提高深部组织区域的图像质量.A numerical model was proposed for the simulation of the nonlinear ultrasound propagation in heterogeneous tissue.First,the coupled nonlinear wave equations for pressure and velocity were obtained based on 1-st order nonlinear wave equations in soft tissue to reduce the complexity of numerical computation.Then,k-space method was used to solve the derived nonlinear wave equations to reduce the memory usage and the computation time of the simulation,while preserving the computation accuracy.Compared with the analytic solution of a 1-dimensinal problem and the finite-different time-domain（FDTD）results of a 2-dimensinal problem,and the accuracy of the proposed model was validated.With grid size of 1/9of the wavelength and Courant-Friedrichs-Lewy（CFL）of 0.3,the square errors of the proposed model and the FDTD method are 0.0125%and 42.5%,respectively.Medical harmonic ultrasound imaging was simulated using the proposed method based on a digital human abdominal map.The results show that image quality can be improved in the deeper tissue by using the harmonic signal.

关 键 词：非线性声学 波动方程 超声成像 k空间方法 谐波成像 

分 类 号：TN98[电子电信—信息与通信工程]