Experimental Study On Thermal Field In The Vicinity Of Arterial Bifurcation In Microwave Ablation Therapy

As the fourth therapeutic method to cure malignant tumor, thermal ablation therapy has been widely used in clinical treatment of cancer in recent years. Microwave ablation therapy becomes to be an effective therapeutic method because it can get deeper ablation lesion. It aims at increasing the temperature of malignant tissues to above 54℃in order to destroy the tumor by microwave energy. Blood in the vessel plays an important role in determining temperature profiles of heated tissues, and the bifurcation is the most important feature of the complex blood vessel network. This paper investigated the temperature field in the vicinity of arterial bifurcation in microwave ablation therapy.In this paper, Experimental instruments were setup to measure the temperature field in the vicinity of arterial bifurcation in the microwave ablation therapy. A muscle-equivalent phantom was used to instead of liver tissue in the experiment. The liver artery of human was simulated by a copper tube with Y bifurcation. Different water flow velocities were maintained in the tube, which are in the typical range of blood flow velocities in liver arteries of human. Copper-constantan thermocouples (TCs) were used to measure the temperature near the arterial bifurcation. Different blood flows were set to investigate the effect of different blood flows in the vessel on the microwave ablation field, and different locations of the microwave antenna was set to investigate the effect of distances between the microwave antenna and the blood vessel on the ablation lesion.Experimental results showed that, when the microwave antenna was 10mm away from the vessel, the heating pattern was not symmetrical about the antenna because the heat convective of blood, and large temperature gradient existed near the blood vessel. Meanwhile, the higher was the blood flow, the smaller was the heating pattern. When the antenna was 15 mm away from the blood vessel, it was seen that the heating pattern was more circular, and the temperature contours with two blood flows were almost overlapped. When the antenna was 20 mm away from the blood vessel, the heating pattern was circle, and almost symmetrical about the microwave antenna.This research provided the experimental referenced value for the processing method of arterial bifurcation in the microwave ablation therapy in the clinical application. The effect of blood on the temperature field can be ignored if the distance between blood vessel and the microwave antenna exceeds 20 mm. Vessel occlusion can be avoided before thermal ablation therapy. The effect of blood flows on the microwave ablation field were different if the distance between blood vessel and the microwave antenna is less than 15mm, and the higher was the blood flow, the smaller was the heating pattern. While, the effect of blood flows on the microwave ablation field were same if the distance between blood vessel and the microwave antenna exceeds 15 mm.