Large and round ablation zones with microwave ablation: A preliminary study of an optimal aperiodic tri-slot coaxial antenna with the π-matching network section

Abstract Microwave ablation (MWA) is a promising thermal therapy that uses heat to kill tumors. A large ablation zone with high circularity is desirable in clinical setting because most tumors are nearly spherical shapes. Single or multiple slot antennas are favored in MWA due to their good clinical outcomes, small dimensions and easy fabrication. However, it is difficult for those antennas to create a sufficiently large and round ablation zone. In this study, an aperiodic tri-slot antenna with π-matching network section was proposed for creating large and round ablation zones in liver tissues. The structural optimization was conducted for both high circularity and good impedance matching. Impedance matching was performed in dehydrated liver tissues instead of untreated liver tissues. The simulation results show that a more localized and round ablation zone can be achieved by aperiodic tri-slot antenna compared with periodic configuration. For π-matched aperiodic tri-slot antenna, an ablation zone as large as 5.15 cm in diameter can be achieved with an input power of 45 W and a duration of 10 min. A better time-varied S 11 curve was achieved compared to the condition that matches in untreated liver tissues. A larger ablation zone with a nearly equal circularity can be obtained compared with previously reported periodic ten-slot antenna.