Interstitial heating: experiments in artificially perfused bovine tongues

Isolated perfused bovine tongues were heated with a 2 x 2 hot water tube interstitial hyperthermia system (tube outer diameter 2.0 mm, spacing 16 mm). Tongue blood flow ranged between 0 and 17 ml min-1/100 g. The temperature distribution was mapped with 5 to 8 single thermocouples (diameter 50 microns). Model predictions using both the conventional bioheat transfer equation and the effective conductivity model were compared to the experimental results, with emphasis on the role of blood flow. Results indicate a better qualitative agreement with the k-effective model than with the heat sink model. In this set up a 16 mm spacing proved sufficient for adequate heating between the needles at normal blood flow rates, in the absence of large vessels.