The effect of electron and gamma irradiation on the induction of micronuclei in cytokinesis-blocked human blood lymphocytes.

The effect of electrons and gamma irradiation on the induction of micronuclei in cytokinesis-blocked human peripheral blood lymphocytes was investigated to understand the relative biological effectiveness (RBE) of electrons compared with gamma rays. Blood samples were irradiated with an 8 MeV pulsed electron beam, at a mean instantaneous dose rate of 2.6 x 10(5) Gy s(-1). Gamma irradiation was carried out at a dose rate of 1.98 Gy min(-1) using (60)Co gamma source. A dose-dependent increase in micronuclei yield was observed. The dose-response relationships for induction of micronuclei fitted well to a linear-quadratic relationship and the coefficients alpha and beta of the dose-response curve were estimated by fitting the data using error-weighted minimum chi (2) method. The RBE of 8 MeV electrons were found to be near unity as compared with gamma rays.