A Vasculature Based Nanocryosurgical Model for Tumor Destruction

The vascular model built on porous media approach is a more realistic representation of biological tissue. A vasculature system based axisymmetric cryosurgical model is proposed here for cryosurgery of lung tumor based on the freezing of the vascular region of the biological tissue. A two-temperature model is developed based on the porous medium approach considering the thermal non-equilibrium between the tissue and the blood region. Bioheat transfer phenomenon between tissue and blood involves interfacial heat transfer, perfusion heat transfer and metabolic heat generation in tissue cylinder. To improve the cryothermal penetration inside the tumor tissue, high conductive nanoparticles are injected into it which increases the local freezing rate of tumor region with minimum damage to the surrounding healthy tissue. The blood phase change in the vascular network is modelled through a source based implicit enthalpy method. The proposed model is utilized to simulate cryosurgery for lung lesion. It is observed that the solidification time for 99.9% tumor using Pennes model and Vascular model (e = 0.01) are 414 s and 512 s respectively, which shows that Pennes model overpredicts the freezing of tumor during cryosurgery. The freezing necrosis is found to reduce by 13.95% at 0.05 (volume fraction) nanoparticle concentration.