Effects of Different Ionizing Radiations on Human Cells in Tissue Culture: II. Biological Experiments

Abstract

The inhibition of clone formation by [alpha]-, [beta]-, and X-radiation was measured with human kidney cells in vitro. With [alpha]-radiation an exponential survival curve was found, with X- and [beta]-radiation a more complicated curve was obtained. The sensitive area calculated from the experiments with o-radiation was equal to 42/[mu]2, which was approximately identical to the cross-sectional area of the nucleus. The relative biological effectiveness (RBE) of [alpha]-radiation ranged from 2.5 at high doses to at least 6.0 at low doses. Results of experiments on the addition of [alpha]- and X-radiation are explained on the assumption that the passage of one [alpha]-particle through the nucleus of a cell is sufficient to prevent this cell from clone formation.