Modeling of Radio Frequency Ablation and Electrosurgery: Capturing Tissue Carbonization and Stalling Phenomena

Radio frequency ablation (RFA) and electrosurgery are widely used in clinical practice. This study presents a comprehensive modeling framework for radio frequency (RF) thermal therapies, incorporating both heat transfer and thermally induced state transitions across three tissue states: native, denatured, and carbonized. A key contribution of this work is the ability to capture the stalling phenomenon, where excessive charring (carbonization of the tissue surface) reduces tissue conductivity, preventing the electrosurgical (ES) generator from maintaining sufficient current. We classified electrosurgical operations into four zones and demonstrated that under optimal conditions (zone 2), heat transfer can be neglected, enabling real-time computation suitable for adaptive control in robotic surgery. For nonideal scenarios, we introduced a two-stage chemical kinetics model that accounts for conductivity loss due to carbonization. Validation against experiments on porcine muscle confirmed the model's ability to reproduce observed behavior, supporting its potential for improving surgical planning and minimizing unintended tissue damage.