Testing of Dose-Rate Models with Chlamydomonas reinhardi

Abstract

Survival of Chlamydomonas reinhardi exposed to 1.5-MeV electrons was measured for six dose rates, from 45 to 2700 rad/min; exposure times ranged from 1 to 300 min. When the data were plotted as the quotient of the negative logarithm of the surviving fraction by the square of the dose versus the irradiation time, they fell essentially on a single curve regardless of the dose rate. Study of six dose-rate models found in the literature showed that only one of them, the Accumulation Model, predicts such a single curve; the others predict families of curves, one for each dose rate. The latter five can be rejected as not applying to C. reinhardi. The fit of the Accumulation Model to the data gave a mean recovery time of 24 min.