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数值仿真是预测高强度聚焦超声(high intensity focused ultrasound,HIFU)治疗的温度分布、确定治疗剂量的有效方法之一。本研究采用Westervelt方程的近似式,并结合Pennes生物热传导方程,以猪肝肿瘤为例,在考虑肝组织声学特性对HIFU温度场影响的条件下,通过时域有限差分法仿真研究辐照时间和声强对肿瘤组织内可治疗焦域体积的影响。研究结果表明,一定声强条件下,肝组织声学特性对肿瘤内可治疗焦域的影响随着辐照时间的延长而凸显;可治疗焦域体积随时间增长或声强增大而非线性增加;相同辐照条件下,肿瘤组织内的可治疗焦域体积大于肝组织内的;当可治疗焦域体积一定时,辐照声强和辐照时间呈负相关;同时,等效热剂量判定的可治疗焦域大于温度阈值判定的可治疗焦域,且二者之差随声强而变化。
Numerical simulation is one of the effective methods for predicting the temperature distribution of high intensity focused ultrasound (HIFU) therapy and determining the therapeutic dose. In this study, the approximate equation of the Westervelt equation is used, combined with the Pennes biological heat conduction equation. Taking pig liver tumor as an example, under the condition that the acoustic characteristics of liver tissue affect the HIFU temperature field, the time-domain finite difference method is used to simulate the irradiation time and The Effect of Sound Intensity on the Volume of Treatable Focal Domain in Tumor Tissues The results show that under certain intensity conditions, the impact of liver acoustic properties on the treatable focal region of the tumor becomes prominent as the irradiation time lengthens; the volume of the focal region can be treated to increase with time or the acoustic intensity increases non-linearly. Under the same irradiation conditions, the treatable focal volume in the tumor tissue was larger than that in the liver tissue; when the treatable focal volume was a certain volume, the irradiation intensity was negatively correlated with the irradiation time; at the same time, the equivalent thermal dose was determined. The treatable focal region that can treat the focal region greater than the temperature threshold is determined, and the difference between the two varies with sound intensity.