Two-point control of temperature profile in tissue

Abstract

A strategy for controlling the temperature profile in the tissue with a single applicator hyperthermia system is described. By manipulating the cooling water temperature as well as the heating power, the tissue temperatures in two selected locations can be controlled. By proper choice of these two locations and the corresponding temperature set-points, a temperature maximum can be obtained in a fairly superficial tumour. If the tissue composition and consequently the temperature distribution is fairly regular, a temperature profile above 43°C in the tumour and below that in normal tissue can be obtained along an axis perpendicular to the surface. The controller is self-tuning and provides dynamic decoupling, bumpless transfer and anti-reset windup. Test of the controller by simulation and on a phantom indicates it is superior to the single point controller currently used.

Keywords::

• hyperthermia system
• control
• temperature distribution