体外冲击波碎石焦点区域声压分布的时域有限差分法仿真研究

目的:研究体外冲击波碎石(Extracorporeal shock wave lithotropisy,ESWL)治疗中不同厚度人体组织对ESWL焦点区域大小、位置和声压分布的影响,为ESWL治疗计划的制定提供理论依据.方法:以Reichenberger的ESWL水中实验为参照例,分别建立三维单一人体组织和多层复合人体组织仿真模型,用时域有限差分(Finite Difference Time Domain,FDTD)数值仿真法,数值仿真ESWL治疗中形成的焦点区域.结果:高强度聚焦超声波在人体脂肪、肌肉层中形成的实际焦点区域大小、位置和焦点区域声压分布随着人体脂肪、肌肉层厚度的变化而变化.结论:ESWL治疗过程中由于人体组织厚度的不同,高强度聚焦超声非线性传播而形成的焦距和最大声压不同,对于不同体态的患者在ESWL治疗时,应该采用不同的焦距设定方法.

Finite Difference Time Domain(FDTD) Simulation of Focal Region Sound Pressure Distribution in Extracorporeal Shock Wave Lithotropisy

Objective:To study the influence of different human tissue on the size,position and the sound pressure distribution of focal region in ESWL(Extracorporeal Shock Wave Lithotropisy)treatment,to establish an ESWL treatment plan.Methods:3D calcula- tion models of single human tissue and compound human tissue were established using Richenberger's ESWL experiment setup in water as the example.The focal region in ESWL treatment was simulated by FDTD(Finite Difference Time Domain)method.Results:The ac- tual size,position and the sound pressure distribution of focal region formed by high-intensity focused ultrasound changed with the thick- ness of human fatty and muscle tissue.Conclusions:Because the focus length and the maximal sound pressure of focal region formed by ultrasonic pulse nonlinear propagation changed with the thickness of human tissue,it is necessary to use different method of setting up fo- cus length to fit patients with different posture in the treatment.