A Novel Closed Loop Cryosurgical Device
A novel cryosurgical device has been developed that dramatically improves the cost, convenience, safety, and effectiveness of cryosurgical devices. The device incorporates a mixed gas J-T stage. The fluid mixture is non flammable, non toxic, non corrosive, environmentally safe, and therefore suitable for medical applications. The system is compressor driven utilizing a novel oil free motor. Working temperatures of -115 to -125 °C at pressures of 300 to 350 psi are achieved. Approximately 20 watts of refrigeration are delivered at -120 °C.
The compressor console is portable having a 4 cu-ft volumetric footprint. The cryoprobe has a handle 3.5 cm O.D. and 18 cm length with a probe shaft having a 4 mm O.D. and a 3.5 cm freeze zone. In bench top studies using tissue simulating media (2% gelatin, 98% saline) ice balls of 3.5 – 4.0 cm diameter and 5 cm length with a mass of 48 grams are created. Studies using calf liver tissue in a body temperature water bath show ice balls of similar size and mass (3.5 cm diameter, 48 g). In live goat animal studies, surface temperatures of -115 °C were achieved, and ice balls of 3.8 cm in diameter were created in 10 minutes in the liver. Isotherms below -20 °C were developed at 12 mm radial distance from the probe.
KeywordsHeat Exchanger Cool Capacity Freeze Zone Ofthe Probe Counter Flow Heat Exchanger
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