Induction of chromosome aberrations by 4.9 MeV protons in human lymphocytes

The dose-response relationship and distribution of chromosome aberrations between cells was studied in G0 human peripheral blood lymphocytes following in vitro exposure to 4.9 MeV protons. The dose-response relationship of dicentric yield showed a significant dose-quadratic component and was best expressed by 2.76 X 10(-1) D + 1.36 X 10(-1) D2 (D in Gy). The distribution of dicentrics between cells was over-dispersed compared with a Poisson distribution. Analysis of the data indicated that the over-dispersion was caused by a spatial limitation in the interaction between tracks. The interaction distance was estimated to be around 0.2 microns.