ARTICLE:

• SIMULATION OF CRYO-ABLATION OF THE PROSTATE BY 1, 2 AND 3 EMBEDDED CRYO-SURGICAL PROBES  download article

Z. Magalov
Israel Institute of Technology, Haifa, Israel

A. Shitzer
Israel Institute of Technology, Haifa, Israel

D. Degani
Israel Institute of Technology, Haifa, Israel

ABSTRACT

The transient temperature field developed by simultaneously operating up to 3 cryo-surgical probes embedded in a phase-changing gel was studied numerically. The 1.5 mm OD probes were operated by a high pressure Argon gas and were placed at 5×5 mm configurations. Temperature variations at one location on the surface of the cryo-probe tips were monitored by thermocouples and were used as the boundary condition in the analysis. The freezing problem was solved numerically by ANSYS 7.0 using the enthalpy method. Frozen front propagation was found to be fastest in the radial direction. In all cases the −40°C isotherm, which is considered in the literature to be the lethal temperature for prostate cell destruction, was found to reach its maximal volume rather quickly, and was relatively small in comparison to that of the 0°C isothermal surface. In the one-, two- and three-probe applications the −40°C isotherm attained, after 30 minutes, about 3%, 3% - 6% and 3% - 8%, respectively, of the total frozen volume, depending on probe placement configurations. Results of this study should be useful in the design of probe placement and operation strategies and in understanding the limitations of the freezing-ablation process.

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