Coupled electrical-thermal model for monopolar and bipolar radiofrequency liver tumor ablation

Radiofrequency ablation (RFA) is an alternative cancer treatment that applies radiofrequency electric fields to biological tissues. The subsequent electrical currents induce Joule heating and inflict local thermal damage to the biological tissue. Previous clinical studies demonstrate the possibilities and benefits of applying RFA for the treatment of liver tumors. Currently, most clinical studies focus on monopolar RFA, consisting of a single electrode and a grounding pad, and its therapeutical outcome. This study however focuses on a bipolar configuration where two needle electrodes are inserted at a certain potential difference. In order to assess the temperature elevations in biological tissues, we have developed a computational model. A mathematical model based on Laplace's equation (with appropriate boundary conditions) is used to model the electromagnetic phenomena and is coupled to the bioheat transfer equation. This study compares a monopolar RFA with a bipolar configuration. We investigate the spatio-temporal temperature variations using detailed numerical three-dimensional finite element simulations in biological tissues, corresponding to liver tissue. Results show that the ablated region in between the two needles of the bipolar configuration can be enlarged compared to a monopolar RFA configuration.