A method of treating a region of diseased tissue using a probe is disclosed. A probe cannula is introduced into the tissue of the patient until a distal end of the cannula is located at or proximate to the treatment region. A plurality of electrodes are then deployed from the distal end of the cannula into the treatment region. Energy (e.g., radiofrequency energy) is then delivered through the plurality of electrodes to the tissue. The cannula is then secured to an immobile object external to the patient. The treatment region is irradiated with a therapeutically effective dose of an ionizing radiation while the plurality of electrodes remain at least partially advanced within the treatment region and while the cannula remains secured to the immobile object.