[Phenomenological statistics of laser irradiation related metabolic changes in guinea pig livers]

In the past, dosimetric investigations on which hyperthermal therapy radiation planning for minimally invasive treatment of tumours were based were often limited to tissue coagulation. While heatshock proteins identified by biochemical basic research provided a fundamental knowledge of the thermal processes of tissue reactions between 42 degrees C and ca. 45 degrees C, the resulting understanding was insufficient to serve as a basis for radiation planning. For this reason, the Arrhenius formalism has so far been used as a good approximation for the complex description of the hyperthermal tissue reactions, with the activation energy being employed as statistic energy threshold for irreversible tissue coagulation. Our investigations were aimed at elucidating whether this formalism could be kept reproducible for tissue damage as temporal accumulation with an implicit biochemically balanced feedback mechanism, i.e. below the coagulation threshold. In our experiments we chose the fluorescence-technical measurement of the NADH concentration as a vital parameter to obtain a more informative statement in a preliminary phenomenological approach. The two most striking differences--as compared with the vitality measurement from the Arrhenius formalism--are the negligible variations in the damage integral (as compared with the phenomenological metabolic reactions acquired by cyclic heating), and the conclusion that the Arrhenius formalism as quasi-linear correlation between metabolic dynamics and tissue damage, will not hold.