Prostate Cryosurgery with Various Numbers of Probes
Chow, Brian; Lau, Ingar; Neidrauer, Mike; Park, Jennifer
Cryosurgery is an increasingly popular way to treat prostate cancer. This process includes inserting one or more probes directly into the prostate to freeze the whole tissue and kill the cancer cells. The number of probes is a determining factor for the effectiveness of the procedure. In our project, we varied the number of probes to see how much of the prostate is frozen in twenty minutes. We used an argon cryogen system with probe temperature of -150oC. Using FIDAP to model the freezing of the prostate, we looked at the temperature data of nodes 2 cm away from the center of the prostate after 20 minutes. For the 1 probe model, the average temperature of the tissue was 25.76 deg C, for the 3 probe the average was 1.05 deg C and for the 5 probe, -16.97 deg C. From these results, it is evident that 1 probe is insufficient for prostate freezing since the temperature only went from 35oC to 25oC in twenty minutes, a mere 10 degree change. Even three probes will be inefficient for prostate freezing since it was twenty degrees away from reaching the optimal temperature of -20oC. We recommend using 5 probes for prostate freezing and looking into using even more probes for more time-efficient freezing. A colder cryogen would also lead to faster cooling. Our model used an argon system; liquid nitrogen with temperature -196oC could be a better alternative.
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