相控阵聚焦超声消融肿瘤的建模与仿真

相控阵聚焦超声可以同时产生多焦点的声场分布,形成较大的治疗热场,能够很好地解决传统球面换能器焦斑体积小,治疗时间长的问题。提出一种基于Rayleigh-Sommerfeld积分和Pennes生物传热方程的三维声热模型,采用有限元分析方法,在ANSYS仿真环境中研究了相控阵聚焦超声治疗时血流灌注对温度场和焦斑的影响。仿真中所有声场和温度场计算均为三维。焦斑体积根据Sapareto-Dewey方程确定。仿真结果表明采用该模型可以较为准确地预测焦斑的生成情况,反映血流灌注对焦斑的影响,血流灌注对焦斑生成的影响将随着照射时间的变化而发生变化。

Modeling and Simulation of Ablation Induced by Ultrasound Phased Arrays Applicator

Ultrasound phased arrays,which are able to generate multiple foci,have advantages of larger lesion size and shorter treatment time over highly focused spherical ultrasound transducers,which produces very small lesion resulting in an impractically long treatment time.A 3D ultrasound thermal model was developed to study effects of blood perfusion on temperature distribution and thermal lesion volumes for hepatic ablation using ultrasound phased arrays.The ultrasound model used Rayleigh-Sommerfeld integral to calculate the pressure fields and the thermal model used Pennes bioheat transfer equations to obtain the temperature distributions.A 3-D finite element representation was developed for modeling the thermal diffusion effects in the target tissue.Pressure and temperature field calculations were fully 3D.The lesion sizes were determined by the formulation proposed by Sapareto and Dewey.Simulation results quantitatively show that this ultrasound thermal model can predict the lesion volumes and the effects of blood perfusion in liver tissue well and truly.Simulation results also show that the effect of liver blood flow varies with sonicaion duration.