Minimally Invasive Microwave Ablation Antenna Designs at 915 MHz and 2.45 GHz

The main objective of this paper is to study two types of minimally invasive coaxial antennas for microwave ablation served for the treatment of liver cancer. Existing microwave antenna designs for ablation are around 2 mm and above in outer diameter which requires a greater hole size in the human body for the insertion of the applicator into the site of tumor. In this paper, we propose miniaturized coaxial slot antennas with an outer diameter of 1 mm which satisfies the medical requirement to minimize the invasiveness. Two types of miniaturized antennas namely monopole with slot and dual slot with an outer diameter of 1 mm are designed and simulated in CST at two different frequencies (915 MHz and 2.45 GHz) to determine the variation in the characteristics of both antennas w.r.t. frequency. Return Loss, Voltage Standing Wave Ratio (VSWR) and Specific Absorption Rate (SAR) pattern of antennas are analyzed to determine the efficiency of the antenna, heating pattern and ablation zone. Simulation results indicate that a dual slot antenna has uniform power distribution around the region of tumor, minimum backward heating and better sphericity in ablation pattern compared to a monopole slot antenna. Also, the antennas operated at 2.45 G Hz are more suitable for creating rapid spherical ablation with a larger diameter compared to the antennas operated at 915 MHz. So we can conclude that a dual slot antenna operated at 2.45 GHz is best suited for microwave ablation.