The decoupling of coupled computer simulations of radio frequency thermal therapy in tissue

Abstract

Knowledge of heat transfer in biological bodies has many therapeutic applications involving either increasing or lowering tissue temperature. Radio-Frequency (RF) energy deposition is a method for increasing the temperature of diseased tissue above 55°C to thermally ablate it. The resulting elevated tissue temperature is due to RF energy deposition as well as tissue thermodynamics. However, it is difficult to separate these two processes on any lab bench or in vivo model, hence computer simulation is a valuable tool for the separation and examination of these two phenomena. Classically, the Pennes' bio-heat equation coupled with electrical field equations in a finite element analysis (FEA) environment provides the governing structure for computer simulations that model energy deposition in biological tissues. In the present work we have modified the computer simulation to allow an artificial partitioning of RF energy deposition and tissue thermal diffusion. An internal cooled RF electrode (CoolTipTM) is analyzed using this partitioning method. This method provides useful knowledge for optimizing the control of RF energy delivery to target tissue.