Patent ID: 7278991

Claim:
A method of controlling an ablation volume depth during surface treatment of a target tissue site, the method comprising: providing a tissue surface treatment apparatus, the apparatus comprising a housing having a proximal end and a distal end including a substantially planar tissue contacting surface having a plurality of apertures each positioned in the tissue contacting surface, the housing defining an interior, an energy delivery device including a plurality of electrodes, each with a tissue penetrating distal end, the plurality of electrodes configured to be advanced from the housing interior through an aperture of the plurality of apertures and into a target tissue site to define an ablation volume at least partly bounded by the tissue surface; an advancement device being coupled to the energy delivery device, the advancement device configured to selectively advance individual electrodes of the plurality of electrodes from the housing interior to a selected deployment depth; positioning the tissue contact surface on a target tissue surface; selectively advancing the plurality of electrodes to the selected deployment depth beneath a tissue surface while avoiding a critical structure; delivering ablative energy from the energy delivery device; creating an ablation volume at a controlled depth below the tissue surface responsive to the electrode advancement device; and minimizing injury to the critical structure responsive to the electrode deployment depth.