Calculation of the Dose-rate Dependence of the Dicentric Yield after Co γ-irradiation of Human Lymphocytes

Summary

The dose relation for dicentrics after in vitro Co γ-irradiation of human lymphocytes with dose rates of 50 and 1·7 rad/min fit the linear-quadratic function y = αD + βD². Compared with 50 rad/min, after 1·7 rad/min αD was unchanged, whereas βD² was decreased by 36 per cent. By applying the mean interaction time t˜ ≈ 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 dose relation of the higher dose rate. This theoretical function is not significantly different 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.