Microwave Hyperthermia Performance Analysis of Wideband Dipole Antenna

Abstract

Hyperthermia (HT) is an adjuvant treatment method aimed at elevating the temperature in target tissues while minimizing the impact on surrounding non-target tissues. Microwave hyperthermia is particularly notable due to the strong interactions between microwaves and biological tissues. The design of a microwave hyperthermia applicator is a critical component of the treatment system, making various antenna designs and arrays a focal point of research in this field. The operating parameters of the designed antenna significantly influence metrics that indicate the efficiency of hyperthermia treatment, such as target-to-body Specific Absorption Rate (SAR) and temperature ratios. In this study, a two-layer hyperthermia applicator utilizing eight microstrip dipole-type antennas with broadside radiation characteristics was proposed. Hyperthermia performance across four different target regions of tissue at 20 frequencies was analyzed. Although this study implemented a simple fat cylinder as a body part, the target-to-body Specific Absorption Rate (SAR) ratios showed that for each target position, a different frequency provided the best performance. Adding the complexity of a real-life problem of an inhomogeneous body with complex geometries, using broadband antennas to perform hyperthermia on different frequencies will provide a significant advantage for focused hyperthermia. The results demonstrate that different frequencies yield varying hyperthermia performance depending on the target position, with mid-range frequencies (2800-3200 MHz) generally providing better SAR distribution and thermal efficiency. Notably, 3000 MHz exhibited the best balance between targeted heating and minimal impact on healthy tissues, while higher frequencies, such as 4000 MHz, resulted in suboptimal performance due to lower realized gain.