Elliptically bent slotted waveguide conformal focused array for hyperthermia treatment of tumors in curved region of human body

Abstract

In present paper, a novel and effective hyperthermia applicator utilizing an elliptically bent conformal array of longitudinal slots in narrow wall of rectangular waveguide is analyzed by two different approaches, viz., the vector potential method and Fresnel-Kirchhoff scalar diffraction field theory. The agreement between two theories is reasonably very good. This configuration is mainly intended as a specialized and very effective applicator for hyperthermia treatment of tumor within curved portions of human body such as abdomen, neck, chest etc. Each slot of the conformal array is excited by a coaxial line probe. It is proposed that the interior of the waveguide be filled with water to provide a good impedance match with the bio-medium. The contour distribution of specific absorption rate (SAR) in x-z plane, SAR distribution in y-direction and parameters such as penetration depth, power absorption coefficient, effective field size (EFS) due to the conformal array as well as single slot are evaluated and compared at 433 MHz. The results for contour SAR distribution at 433 MHz for elliptically bent conformal array are also compared with those for other array configurations such as circularly bent conformal array and planar array. The effect of change in phase and amplitude excitation of each slot of the array on SAR distribution is also examined. The results demonstrate that slotted waveguide conformal array offers marked improvement in SAR distribution and penetration depth over single slot. It also has better focusing ability as compared with planar array for controlled amplitude and phase excitations of the elements.