Dual concentric conductor arrays for microwave hyperthermia: theoretical study of design parameters

Localized hyperthermia has proven to be an effective adjuvant treatment to radiotherapy, with best synergism of treatments obtained for simultaneous application of the two modalities. For this reason, recent efforts have been dedicated to the development of applicators that produce effective heating while maintaining physical transparency to external beam radiation. In this paper, Dual Concentric Conductor (DCC) array applicators are described and their electromagnetic radiation patterns into biological tissue loads are characterized with simulations obtained using the Finite Difference Time Domain (FDTD) method. A number of array configurations are analyzed to study the effects of different applicator construction characteristics such as size, electromagnetic feed, and interelement spacing. Experimental measurements for a large 3×6 element array radiating into a multilayered tissue phantom load are presented and compared to the theoretical simulations of a smaller representative portion of the array. Results demonstrate that the FDTD method is capable of predicting the fundamental radiation characteristics of multiple element arrays. In addition, both analysis and experimental measurements indicate that relatively uniform and adjustable power deposition patterns can be obtained in multilayered tissue loads when arrays are driven with incoherent 915 MHz sources