ABSTRACT
Cryosurgery requires the removal of heat from the tissues, thereby producing localized freezing to an appropriate extent for therapy. The procedure is based on established well-known cryobiological principles, which originally were formed during investigative work on cryopreservation of cells and tissues and on the pathogenesis of frostbite. From the beginning of the modern era of cryosurgery, when automated cryosurgical equipment became available early in the 1960s, dosimetry in terms of temperature and duration of the freeze-thaw cycle was an important issue. In the 1960s, Cooper wrote that a tissue temperature of 20C or colder, held for 1 minute or longer, was sufficient to produce necrosis of tissue.1,2 This statement was based on his experimental work but also has some basis on investigations of frostbite.3
