Dose-effect relationship of chromosome aberrations induced by 23 MeV alpha particles in human lymphocytes

The dose-effect relationship and intercellular distribution of chromosome aberrations were studied in human peripheral blood lymphocytes irradiated in vitro with 23 MeV alpha particles. The frequency of dicentrics, mu, was best expressed by a linear-quadratic model, mu = 7.55 X 10(-1) D + 2.1 X 10(-2) D2, although the dose-quadratic component was not significantly different from zero giving a fit to a linear model mu = 7.93 X 10(-1) D also (D in Gy). The intercellular distributions of dicentrics were over-dispersed compared with Poisson distribution, and the dispersion index as expressed by the relative variance increased with the increase of mean dicentric yield. Stochastic considerations based on the relative variance indicated the presence of inter-track interaction in the formation of dicentrics by alpha particles. Modification of the dose-response relationship by selective loss of cells with more damage is discussed.