Technique for microwave-induced hyperthermia in superficial human tumours.

In order to induce local hyperthermia in superficial tumours a computer system using a 2,450 MHz microwave generator connected to a circular (diameter 90 mm) direct contact applicator was constructed based on invasive temperature control. Small thermistor probes with a diameter of 0.6 mm are inserted in the tumour and surrounding tissues. Eight thermistors can be used simultaneously and one of them is chosen as the "master'. The automatic control system used a pulsed irradiation technique to avoid the problem with interactions between the metallic wires of the temperature probe and the electromagnetic field. With the system it was possible to control the temperature at the master thermistor within +/- 0.5 degrees C from the preset value.