Adaptive Radio-Frequency Hyperthermia Phased-Array System for Improved CancerTherapy; Phantom Target Measurements

摘要

An adaptive radio-frequency hyperthermia system for improved therapeutic tumorheating is investigated. Adaptive array techniques are used to modify the electric-field and temperature distribution in hyperthermia experiments with phantom targets. A commercial hyperthermia phased-array antenna system at the SUNY Health Science Center in Syracuse, New York, has been modified to implement adaptive nulling and adaptive focusing algorithms. The hyperthermia system is the BSD Medical Corporation Model BSD-2000 with Sigma-60 annular phased-array antenna applicator. The applicator operates from 60 to 120 MHz and consists of four pairs of dipole antenna radiators. The four-channel transmit array is made adaptive by software modifications which invoke a gradient-search feedback algorithm. The gradient-search algorithm implements the method of steepest descent for adaptive nulling and the method of steepest ascent for adaptive focusing. The feedback signals are provided by electric-field short-dipole probe antennas. With the proposed adaptive hyperthermia array design concept, it may be possible to maximize the applied electric field at a tumor position in the target body and simultaneously minimize or reduce the electric field at target positions where undesired high-temperature regions (hot spots) occur. The measured phantom-target data indicate that adaptive nulling can reduce the electric field at one or more target positions while simultaneously focusing at a deep-seated position within the target. Tumor heating, Adaptive phased array, Microwave hyperthermia, Adaptive focusing, Cancer therapy.