Numerical Analysis of the Heat Sink Effect of Blood Vessels on Hepatic Radiofrequency and Microwave Ablation

During the last 3 decades, different therapeutic methods have been used for cancer treatment. Hyperthermia is one of these methods, which destroys the tumor cells with applying temperatures about 41-46°C. Thermal ablations of hepatic tumors near large blood vessels are affected by the heat sink effect of blood vessels. In this study, the heat sink effect of blood vessels on hepatic mono-polar radiofrequency and microwave ablation was investigated. The simulation is performed by numerical solution of bio-heat transfer equation with equations of electrical current or electromagnetic waves. To analyze the heat sink effect of blood vessels, the tissue is modeled with and without blood vessel. The fraction of necrotic tissue is determined for 3 different diameters of blood vessels including 5, 10, and 15 mm. The results show that when the applicator distance to the blood vessel is less than or equal to 8 mm, the necrotic value significantly decreases and the heat sink effect becomes important; however, for distances larger than 30 mm, the necrotic value does not change and the heat sink effect is diminished. The heat sink effect increases with blood vessel diameter due to the blood flow increase. In addition, the results indicated that the microwave ablation is less affected by the heat sink effect in comparison with the mono-polar radiofrequency.