Relationship between Arrhenius models of thermal damage and the CEM 43 thermal dose

Thermal Dose, expressed as equivalent minutes of exposure at 43 °C, is typically used as the measure of relative treatment effectiveness in tumor hyperthermia work while an Arrhenius model is more typical in skin burn and other higher temperature studies. The two methods are closely related, mathematically, but yield very different styles of prediction. Arrhenius calculations in numerical models can be used to predict the probability of irreversible thermal damage and are capable of making such predictions for several different markers of thermal damage simultaneously. CEM 43 contours are not probabilistic by nature, though they do contain that information. If one additional data point is known - i.e. D0 at 43 °C - a probability plot identical to the Arrhenius result may be created from a CEM 43 result. Absent that value, it is not possible to do. This paper de-constructs both measures of irreversible thermal alteration, showing their inter-relationship, and presents methods to convert one measure into the other. Specific examples of damage predictions using thermal damage coefficients from published data are discussed with particular emphasis on the original pathologic data from 1947. Obtaining probabilistic predictions from the two methods is presented, and strongly advocated.