Fig. 1. Induced-repair model of PLDR. (a) Typical cell survival curve with evidence of HRS/IRR. Broken line shows low-dose extrapolation from linear quadratic model applied to high-dose survival data. Solid line shows induced repair fit. (b) The description of the sublethal repair half time of normal cells by Elkind et al. (1965). The hamster cells were irradiated with total 1558 cGy, which divided evenly into 763 cGy and 795 cGy with different intervals and cells were placed at room temperature during the interval. PLDR: pulsed low-dose rate; HRS: hyper-radiosensitivity; IRR: increased radioresistance; LQ: linear-quadratic model.