Analytical and numerical study of tissue cryofreezing via the immersed boundary method

Abstract

Cryosurgery is accepted as a favorable treatment option for eradicating undesirable cancerous tissue due to its minimally invasive nature. This work presents a finite difference study of a biological liver tissue undergoing cryofreezing using the immersed boundary method (IBM). The liver tissue is treated as a non-ideal material having temperature-dependent thermophysical properties. Numerical results exhibit good agreement with available data from literature with maximum errors of 1.7% and 1.5% for simulations and experiments, respectively. The influence of heating effect due to blood flow (through the vessel surface) has been investigated by applying the boundary condition-enforced IBM. Results have indicated that the heat source term due to the blood flow in the vessel embedded in the bioheat transfer equation significantly impacts the tissue temperature profiles and thermal gradient histories. In addition, the ice fronts, namely, 0°C and −40°C, progression can vary by as much as 35% at 500s when the distance between the cryoprobe and the major blood vessel varies. This work has also demonstrated that applying the IBM to a bioheat model focusing on tissue cryofreezing is highly appropriate as far as the analysis of tissue freezing in the vicinity of major blood vessels is concerned.