THERMAL PROPERTIES OF HUMAN SOFT TISSUE AND ITS EQUIVALENTS IN A WIDE LOW-TEMPERATURE RANGE

A prescribed amount of heat to be removed from biotissues during cryogenic treatment is currently calculated with the use of simple prediction models. Therefore, a signifi cant distinction exists between the calculated and actual doses during the operation. For reliable simulation, it is necessary to have accurate thermal properties of human tissues in a wide low-temperature range, but in the literature the data regarding these thermal properties are inconclusive. In the present paper, the thermal properties of human prostate, kidney, liver, and pancreatic tissues are analyzed. Using differential scanning calorimetry (DSC), the specifi c heat capacity in the temperature range from –160 to 40^o С, the latent heat of melting, and the initial ice melting temperature are measured. The moisture content and cryoscopic temperature of these tissues are also investigated. Due to the diffi culties with getting access to a human cardiac muscle and large specimens of other human biotissues, in the present study equivalents (porcine tissues) are used on the basis of their high similarity to human biotissues. In this case, only the thermal conductivity of a porcine cardiac muscle is determined. Based on the measurement results, the thermal properties of the same tissue type and of different types (including healthy tissues and tumors) are compared. The adaptation of experimental data for simulation software is proposed. The impact of the accuracy in determining the thermal properties on the thermal diffusivity is analyzed. The prospects in predicting the thermal properties of different biological tissues are considered. Based on the data obtained, it is possible to more accurately simulate heat transfer during cryoexposure.
   
Author:  I. V. Agafonkina, A. G. Belozerov, A. O. Vasilyev, A. V. Pushkarev, D. I. Tsiganov, A. V. Shakurov and A. A. Zherdev
Keywords:  differential scanning calorimetry (DSC), heat capacity, thermal conductivity, biological tissue, prostate, liver, pancreas, heart, kidney
Page:  233