Coax-Fed Dipole-Type Applicator for Hepatic Cancer RF Ablation

Cancer is the third leading cause of mortality in t he world and is one of the most difficult diseases to detect and cure. This fact motivates us to investigate a treatment m e hod by using radiofrequency (RF) ablation. RF abl ation therapy kills cancer cells by electromagnetically heating t hem up. The treatment uses an applicator that is in serted into the body to heat the cells. The cancer cells are exposed to a temperature of more than 60 °C in short duration (a few seconds to a few minutes), thereby causing cell destruction loca lly. To ensure effective treatment, a minimally inv asive method is selected so that good local temperature distributio n inside the cancer cells can be achieved. In this paper, a coax-fed dipole-type applicator is proposed for interstitial irradiation technique in hepatic cell treatment. The applicator design is conducted by simulation in CST Microwave Studio to obtain an appropriate size at operating frequency o f 2.45 GHz. We also consider localizing the ablation area by de signing the tip of the applicator such that the mai n electromagnetic radiation locally exists around it. The proposed ap plicator is inserted into a simple phantom model of an adult human body with normal and cancerous liver cells. Both si mulation and measured results show that the propose d applicator is able to operate at center frequency of 2.45 GHz in a blood droplet-type ablation zone. A temperature o f 60 °C around the cancer cell can be achieved by simulation. More over, a square four-array applicator is analyzed to increase the ablation zone for a larger tumor cell. The simulation results show that a reasonably wider local ablation area can be achieved.