移动式微波全身加热的理论模型与温度预示

Theoretical Modeling and Temperature Prediction in Moveable Microwave Based Whole Body Hyperthermia

针对移动式微波全身热疗系统从微波发射到电磁吸收直至诱发人体全身温度响应的过程,建立了相应的物理场和热效应理论模型,结合全身热疗中的关键因素,对已有三例患者的热疗数据进行评估,提出了可用于临床全身热疗的温度预示和数据监控方法。研究表明,热疗机在磁控管内建立的915 MHz微波震荡符合Poynting定理的远场特性及Maxwell定律电磁传播特性,电磁能到达人体后在人体电介质内发生热吸收和转化。考虑体内热容分布和主动调控作用,引入房室模型对全身热量的传输进行刻画。根据全身热疗有效性和安全性要求,可将体核、体表及大脑温度的量化作为全身热疗中重要的评估标准。

In this study a mathematical model was established to quantify the physical and thermal field effect of energy emission,propagation and in vivo thermal absorption and distribution during a movable microwave radiation in whole body hyperthermia therapy through interpreting the multiphysics process thus involved.According to the evaluation with the recorded data from 3 patients,temperature prediction and measurement methods were proposed for clinical uses.The governing laws for the 915 MHz microwave released from the magnetron in this analysis follow the Ponyting law and Maxwell law.The electromagnetic energy would be absorbed and converted to heat after entering into human body.Taking account of tissue thermal capacity distribution and active regulation mechanisms,a compartmental model was developed to characterize the temperature responses.It is proved that the temperatures of body core,skin and brain can serve well as an index for evaluating the whole body hyperthermia according to the efficiency and safety requirement.