Evaluation and optimization of the electromagnetic performance of interstitial antennas for hyperthermia.

Effective and realistic evaluation of the performance of interstitial antennas for microwave hyperthermia involves: (a) calculations of the radiation characteristics of these antennas, including those of multi-section designs, and (b) the development of 3-dimensional models of tumors and the computation of the power deposition patterns in these tumors due to their irradiation by an array of interstitial antennas. In this paper, we address both of these issues. Specifically, we developed numerical models for calculating the radiation characteristics of multi-section insulated antennas, and we utilized a 3-dimensional model based on a volume integral equation formulation for calculating the power deposition pattern in tumors. Numerical results were verified by comparing them with experimental data available in the literature. New numerical data are presented to illustrate the advantages of multi-section designs over uniformly-insulated interstitial antennas and to show the feasibility of using amplitude and phase steering capabilities to control the power deposition patterns of an interstitial antenna array. The role of each section in a multi-section antenna design in guiding versus radiating the electromagnetic energy and hence in controlling the power deposition pattern of multi-section antennas is also described.