Time scale of radiation-induced oxygen depletion and decay kinetics of oxygen-dependent damage in cells irradiated at ultrahigh dose rates

A mathematical model is proposed to explain the experimental observation of breaking survival curves obtained in ultrahigh dose rate studies. The model examines the kinetics of radiation-induced oxygen depletion in calls and of the decay and reactions of oxygen-dependent damage postulated to be involved in the oxygen effect for cells. A reaction scheme is assumed for radiochemical oxygen depletion where a set of radiation-induced species reacts with and binds dissolved oxygen molecules. The proposed theory of Howard-Flanders and Moore on oxygen-dependent injury is also adopted to provide a description of the reaction and decay characteristics of the oxygen-dependent damage. A computerized examination of the time-dependent interaction of the above described processes indicates that calculated breaking survival curves are in good agreement with those observed experimentally