射频消融时组织加热的热动力学模型及初步分析

A preliminary analysis of thermodynamic model of tissue heating during radiofrequency ablation

兼顾放电时分布式加热和瞬时的热传导效应，本文推导出一个组织加热的热动力学模型。在作了初步分析之后得到了几个结论：（１）稳定后的温度分布沿径向符合１／ｒ２规律，而不是早先认为的１／ｒ规律。（２）温度上升而趋向于稳定值的速度是随距离ｒ而变的，在界面附近它服从指数上升规律而时间常数还与ｒ２成正比。（３）用恒定功率控制损伤斑大小与用恒定温度监控本质上没有区别。（４）不论用哪种方法，最大损伤斑的尺寸是不变的，它仅仅与电极头半径有关，大约是半径的２．４９倍。

In this paper, a thermodynamic model for tissue heating was derived by taking into account the effect of the distributed heating during RF energy delivery and the temporal conduction. Several conclusions were reached from primary analysis. These are: (1) The radical temperature distribution at the steady state coincides with the rule of 1/r2, but not with the rule of 1/r as believed earlier. (2) The temperature rise rate approaching the stable value varaes as with the distance within the nearfield of electrode-tissue interface. It obeys the mono-exponential rule with the time constant proportional to r2.Essentially, to control lesion size by power regulation was the same as by temperature regulation. (4)The maximum lesion size was determined ultimately by the radius of the electrode tip , no matter what method was used. It is about 2.49 times the radius.