Apparatus for heating tissue and employing protection against transients

Claim 1

Apparatus for treating tumors in humans and animals, comprising, radio frequency oscillator means, amplifier means coupled to the output of said radio frequency oscillator means for producing an amplified radio frequency output signal, electrode means coupled to said amplifier means, said electrode means including a pair of uninsulated conductive electrodes having a configuration adapted to pass an electric current directly into the tissue to which they are attached for passing current through both the tumor and the surrounding tissue, said electrode means and said amplifier means forming with the tissue between said electrode means an electrical circuit, said electrical circuit exclusive of the tissue including inductance means and capacitance means selected such that the capacitive reactance of said circuit is substantially equal and opposite in phase to the inductive reactance thereof, the value of said capacitance means also being selected to prevent transient very low frequency pulses and direct current pulses occurring in said circuit when said amplifier means are turned on and off from reaching the tissue, and means for controlling the power of said amplifier means to avoid heating the surrounding tissue beyond a preselected temperature level while allowing the tumor to heat beyond the preselected temperature level.