Effect of 25 and 50 MeV protons on human lymphocyte chromosomes in vitro

A culture of human blood lymphocytes in g1-stage has been irradiated with protons with the energy of 25 and 50 MeV and with X-rays of 200 kV in the doses from 25 to 400 rad. Protons as well as X-rays have induced different types of chromosomal aberrations, the number of which increased with irradiation dose. Under the effect of irradiations with high linear losses of energy the amount of couple fragments increased and the number of dicentrics and rings decreased. According to the total yield of aberration number coefficients of the relative biological activity (RBE) of protons have been established and proved to be equal to 1. Coefficients of RBE for 25 and 50 MeV protons were equal to 1.50 +-0.1 and 1.40+-0.10 respectively according to the formation of couple acentric fragments