Interpretation of the Shoulder of Dose—response Curves with Immediate Plating in Terms of Repair of Potentially Lethal Lesions During a Restricted time Period

SummaryIt is shown theoretically that a shouldered dose—response curve may be obtained when repair of Poisson-distributed potentially lethal lesions occurs during a restricted time period between plating irradiated cells on nutrient agar and fixation of potentially lethal lesions. This interpretation is supported by experiments showing that an increased shoulder width of the dose—response curve is observed when irradiated cells are given more time for repair of potentially lethal lesions.