Calculation of the dose-rate dependence of the decentric yield after Co gamma-irradiation of human lymphocytes.

The dose relation for dicentrics after in vitro Co gamma-irradiation of human lymphocytes with dose rates of 50 and 1.7 rad/min fit the linear-quadratic function y=alpha D + beta D2. Compared with 50 rad/min, after 1.7 rad/min alpha D was unchanged, whereas beta D2 was decreased by 36 percent. By applying the mean interaction time t approximate to 110 min for primary breaks, determined in an earlier experiment, and Lea's G-function, a theoretical dose relation for 1.7 rad/min can be calculated from the corresponding experimental curve. Thus, from calibration curves with conventional dose rates dose-effect curves for low dose rates can be derived without the need for time-consuming chromosome analyses.