Repair of Potentially Lethal Radiation Damage: Comparison of Neutron and X-Ray RBE and Implications for Radiation Therapy

Abstract

Experiments with Chinese hamster cells showed that neutron irradiation does not result in repair of potentially lethal damage (PLD), i.e., that which can be influenced by changes in environmental conditions following irradiation. Since PLD is presumed to be repaired in tumors but not in normal tissues, this absence of differential sparing of tumor cells relative to normal tissues, a feature characteristic of irradiation with X-rays, represents an advantage of neutrons in addition to their reduced O2 effect. At a given dose, the difference in relative biological effectiveness (RBE) between tumors and normal tissues corresponds to a 5% increase in tumor dose with no concomitant increase in dose to normal tissues, which could be significant in cancer therapy.