A system for treating a target region in tissue beneath a tissue surface comprises
a probe for deploying an electrode array within the tissue and a surface electrode
for engaging the tissue surface above the treatment site. Preferably, surface electrode
includes a plurality of tissue-penetrating elements which advance into the tissue,
and the surface electrode is removably attachable to the probe. The tissue may
be treated in a monopolar fashion where the electrode array and surface electrode
are attached to a common pole on an electrode surgical power supply and powered
simultaneously or successively, or in a bipolar fashion where the electrode array
and surface electrode are attached to opposite poles of the power supply. The systems
are particularly useful for treating tumors and other tissue treatment regions
which lie near the surface.
