Modelling individual temperature profiles from an isolated perfused bovinetongue

To predict the temperature distribution during hyperthermia treatments a th ermal model that accounts for the thermal effect of blood flow is mandatory . The DIscrete VAsculature (DIVA) thermal model developed at our department is able to do so: geometrically described vessels are handled individually and the remaining vasculature is modelled collectively. The goal of this p aper is to experimentally validate the DIVA model by comparing measured wit h modelled temperature profiles on an individual basis. Temperature profiles in an isolated bovine tongue heated with three hot wat er tubes were measured at three controlled perfusion levels, 0, 6 and 24 ml (100 g)(-1) min(-1). The geometries of the tongue, the hot water tubes, th ermocouples and discrete vasculature down to 0.5 mm diameter were reconstru cted by using cryo-microtome slices at 0.1 mm cubic resolution. This recons truction of the experimental set-up is used for the modelling of individual profiles. In a no-flow agar-agar phantom, DIVA showed nearly perfect correspondence b etween measurements and simulations. In the isolated bovine tongue the corr espondence at no flow was slightly disturbed due to geometrical distortion in the reconstruction of the experimental set-up. Measurements showed decre asing temperature profiles with increasing perfusion. DIVA correctly predic ted this decrease in temperature as well as the thermal impact of a large v essel close to a thermocouple. Blood flow was modelled using discrete vascu lature and using a heat sink model. Although at 24 ml(100 g)(-1) min(-1) co rrespondence between heat sink simulations and measurements was reasonable, modelling discrete vasculature yielded the best correspondence at both 6 a nd 24 ml (100 g)(-1) min(-1). The results strongly suggest that with accurate data acquisition DIVA can p redict temperature profiles on an individual basis. For this kind of patien t-specific treatment planning in the clinic, geometrical reconstruction of the anatomy, vasculature and the heating implant is necessary. MRI is capab le of providing these data. Further research will be done on thermal simula tions of actual clinical hyperthermia treatments.