Fast Output Sampling Controller for Hyperthermia Systems

A tumor layer surrounded by muscle layer is modeled by bio heat transfer equation. A state space model to the bio heat transfer problem is obtained by a finite difference method. This model is reduced to a lower order model. A fast output sampling feedback controller is designed for controlling the temperature profile in hyperthermia cancer treatments. The performance evaluation for the controller is done using simulations with a one dimensional layered models of the tumor, which is heated by a single scanned focused ultrasound transducer. The performance criterion in terms of time domain specifications for the controller has been framed and the performance analysis is carried out for varying blood perfusion rate. The Fast output sampling controller is capable of giving desired closed loop behavior and closed loop stability. Linear Matrix Inequality optimization is used to reduce the magnitude of the control effort needed to control the temperature in tissue.