Design of invasive and non-invasive antennas for the combination of microwave-hyperthermia with radiation therapy

Microwave hyperthermia is a method to elevate the temperature of the tissue. Combination of hyperthermia and radiation therapy can be very effective for treating cancer, because the temperature rise and dose by them may be able to be suppressed to optimized levels. In this paper, Invasive and non-invasive antennas for hyperthermia were designed, and an interstitial microwave antenna array hyperthermia system was used on a series of different phantoms to generate localized hyperthermia fields inside those phantoms. Coaxial-slot antenna is a minimally invasive antenna to generate radio frequency microwave field inside the phantoms. As a result of application of coaxial-slot antenna on different phantoms, energy absorption and temperature change occurs. In parallel, a non-invasive antenna - micro-strip patch antenna - was designed and applied on different phantoms. A critical parameter in any hyperthermia system is the Specific Absorption Rate (SAR), which gives information about the energy absorption in the different tissues. In this paper, the theoretical, measured and simulated values of SAR in different tissues have been compared. Both theory and experiment demonstrated that the maximum SAR occurred in the junction plane of antenna array. These experiments have been conducted using a frequency of 2.45GHz.