to be utilized based on the type of suitable energy being utilized size and shape of ablation volumes is primarily dependent on the thermal spread and energy flow patterns in addition ablation volume is also dependent on the type of tissue being ablated as well as tissue 39 s inherent conductivity and dielectric properties which govern the thermal spread and energy flow therethrough the type of energy being used in ablation e g rf microwave etc may also have a bearing on the patterns of cell death and apoptosis thermal injury begins at 41 u00b0 c with time of the heat exposure required for complete cell death exponentially decreasing above 42 5 u00b0 c see dickson j a caldewood s k temperature range and selective sensitivity of tumors to hyperthermia a critical review ann n y acad sci 1980 vol 335 pp 180 205 rhee j g song c w thermotolerance of organized tissues and tumors in henle k j ed thermotolerance vol 1 boca raton fla crc press inc 1987 pp 73 95 apoptosis may be seen at temperature below 46 u00b0 c with necrosis beyond this threshold see liu f f wilson b c hyperthermia and photodynamic therapy.