Abstract
Conventional monitoring of malignant tumors with thermocouple needles is useful, but has disadvantages. Temperatures are recorded all along the shafts of the thermocouple needles and there is a lag of 10 to 15 seconds before precise temperature is recorded at the tip of the needle. This delay may lead the clinician to underfreeze leions. An alternative and more precise monitoring device that measures the flow of electrical current or the cessation of electrical flow (resistance) as an indication of effective cryonecrosis during freezing is described in this paper. This method affords absolute accuracy and at the same time allows monitoring up to five separate focal areas within a lesion instead of a single site as is currently done with thermocouples.