Finite Element Analysis of the Re-entrant Type Resonant Cavity Applicator for Brain Tumor Hyperthermia

In this paper, we have proposed a new heating method in which high frequency electric fields in a re-entrant type resonant cavity are used for the heating of deeply seated tumors. In this method, a human head is placed between the gap of the inner re-entrant cylinders, and is heated with electromagnetic fields stimulated in the cavity without contact between the surface of the human head and the applicator. Here, we proposed a new method to control the heating area. In this method, the resonant frequency inside the cavity was changed, then we use the TM₀₁₀-like mode and the TM₀₁₂-like mode from various types of the resonant frequency. First, the computer simulation results of electric and magnetic field patterns are presented. Second, a comparison of the heating properties of TM₀₁₀-like mode and TM₀₁₂-like mode are discussed. The heating area of the center of agar phantom is more concentrated by using TM₀₁₂-like mode than that of using TM₀₁₀-like mode. From these results, it is confirmed that the proposed method can be controlled to heat the various sizes of deep tumors.