WATER VAPORIZATION FROM HEATED TISSUE - AN IN-VITRO STUDY BY DIFFERENTIAL SCANNING CALORIMETRY

Background and Objective: The heat balance equation is central to mode ling laser vaporization of tissue. Because about 70% of tissue is wate r, energy loss due to water vaporization becomes an important consider ation in modeling. In this study, the rate and pattern of water vapori zation from various animal tissues studied by differential scanning ca lorimetry (DSC) are reported. Study Design/Materials and Methods: DSC thermograms of fresh muscle, liver, and kidney tissues were made at he ating rates of 2 degrees C/min, 5 degrees C/min, and 10 degrees C/min in the temperature range of 30-150 degrees C. Thermograms of vacuum-dr ied muscle sample were also made to establish that the endotherms obta ined were essentially due to the water in the tissue. Results and Conc lusion: Two broad peaks-one below and the other above 100 degrees C-ar e seen in all the endotherms. The peaks are attributed to the structur al and compositional features of tissue and tissue water. The two-stag e vaporization pattern has importance in modeling tissue heating by a continuous-wave Nd:YAG laser. (C) 1996 Wiley-Liss, Inc.