Hematopoietic Death of Mice after Whole Body Carbon Beam Irradiation and Its Mitigation by Radiation Modifiers

Abstract

Radiation therapy using heavy ion beams has a merit compared to low LET radiation therapy using such as X-rays and gamma-rays that injury to normal tissues is reduced. However, it is still possible that high LET heavy ion radiation induces radiation injury along the beam at entrance side. Here we report LD50/30 value for haematopoietic death of mice after whole body carbon beam irradiation. The LD50/30 value was about 5.5 Gy. By comparing with the value of 6.6 Gy for X-ray irradiation, RBE value was calculated to be 1.2. Next, we examined effects of radiation modifiers (cysteamine, WR-2721, zinc-yeast, and gamma-TDMG) on the survival of mice. Mice were whole-body irradiated with the carbon beam at 6.0 Gy and 30-days survival was measured. All the modifiers examined showed significant increase of the survival rate similar to what was shown in X-ray irradiation experiments.