RF tissue ablation apparatus and method

A method and apparatus for controlling the extent of tissue ablation are disclosed. The method utilizes delivering energy from an energy deliver device to a plurality of deployed electrodes and regulating energy delivered to the electrodes based on the temperature sensed by at least one remote elongate sensor element. A control device may be used to supply energy to the electrodes, to produce tissue ablation that advances from individual-electrode ablation regions to fill a combined-electrode ablation volume. Information from the sensor element(s) is used for determining the extent of ablation in the regions of the sensor elements. The supply of energy to the electrodes can thus be regulated to control the level and extent of tissue ablation throughout the combined-electrode volume.