A multiple RF heating system for experimental hyperthermia in small animals.

A versatile system is described for locally heating a number of mouse tumours simultaneously using RF capacitive coupling. The system is designed around a single RF power amplifier supplying a number of heating jigs via an efficient isolated power splitter. It is primarily intended for use at 13.56 and 27.12 MHz, but can operate from 2-30 MHz and could be modified for use at other frequencies. Microthermocouples are used for monitoring the intra-tissue temperature quasi-continuously, by making temperature measurements every 220 ms within 20 ms periods during which the RF power is turned off to all the jigs. This method avoids any artefacts in the temperature measurement which are associated with electromagnetic interference. Thermostatic regulation of tissue temperature is provided by on-off control of the average power supplied independently to each heating jig.