A Model for the Induction of DNA Damages by Fast Neutrons and their Evolution into Cell Clonogenic Inactivation

Abstract

It has been long stated that cellular inactivation through neutron irradiation is mainly caused by energy deposition in DNA molecules from recoiled secondary charged particles. Complexities associated with neutrons, such as the generally broad energy spectrum and the inherently wide energy spectrum of the induced charged particles, not to mention that the dependence of cellular inactivation by charged particles on radiation quality is yet to be fully understood, make it difficult to check this statement. Recently a molecular model has been proposed that improves the quantitative explanation of the dependence of cellular inactivation by charged particles on radiation quality. An attempt was made to apply this model for analysis of neutron cellular inactivation. As a preliminary result it is suggested that neutron cellular inactivation is caused not only by secondary charged particles but also by an "atomic deletion" effect, generated by a stripped atom recoiling from a DNA molecule. This effect seems to be of significant importance, the inactivation cross section of this effect for fission neutrons is as much as 15% (aerobic conditions) or 55% (hypoxic) of the total, and the severity of one occurrence of atomic deletion by a single neutron is estimated as much as 3.1 +/- 1.1 times (aerobic) or 6.8 +/- 1.2 times (hypoxic) higher than the severity of one event by a single track of a charged particle interacting with DNA.