Optimal Temperature Control with Phased Array Hyperthermia System

A strategy for controlling the temperature distribution in tissue, irradiated by a phased array of RF applicators, described. Using the amptitudes and relative phases from the individual applicators as control inputs, feedback control is established from a corresponding number of measured tissue temperatures. Optimal control theory based on a state-space model of the thermal process is used for designing the multi-variable self-toning controller. Simulations of the two-dimensional temperature distribution in cylindrical homogeneous muscle tissue indicate that it is possible to place a temperature maximum near a given point and to maintain therapeutic temperatures in a specified tumor area while the temperatures in the surrounding tissue are lower.