Formalization and theoretical analysis of the Local Effect Model.
The Local Effect Model (LEM) is a track-structure model that was developed to predict the biological response of a cell to irradiation with any ion. Because it needs to be studied both experimentally and theoretically, a mathematical formalization of the LEM based on three main postulates and three secondary approximations is proposed for a more detailed analysis. The general relationship that links cell survival to the mean number of lethal events is deduced. A Monte Carlo simulation is also proposed to calculate the local dose. It is shown that the local dose is highly heterogeneous even for uniform X irradiations. This observation raises questions about the estimation of the density of ion-induced lethal events from the expression of cell survival after exposure to X rays. Finally, it is shown that a strict theory of local effects based solely on local dose cannot reproduce nonlinear structures in cell survival curves, such as the shoulders observed after low-LET irradiation.
Beuve
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Laboratoire d'InfoRmatique en Images et Systèmes d'Information, Université de Lyon, Université Lyon 1, CNRS, UMR 5205, LIRIS, Villeurbanne F69622, France. michael.beuve@liris.cnrs.fr
D017209:Apoptosis / Q000528:radiation effects*; D002470:Cell Survival / Q000528:radiation effects*; D003198:Computer Simulation; D004307:Dose-Response Relationship, Radiation; D018499:Linear Energy Transfer / Q000502:physiology*; D008954:Models, Biological; D009010:Monte Carlo Method; D011829:Radiation Dosage