ESTRO 2021 Abstract Book

S667

ESTRO 2021

24 h) for 9-14 days. Results

We found colonies to show three distinct growth behaviors: exponentially growing, delayed abortive, or initially abortive (Fig 1(a)). CG rates for the first two types are normally distributed with large relative SDs of up to 80 % and decrease with increasing dose (Fig 1 (b, c)), independent of unirradiated baseline growth rates.

For all doses at all times the size distributions of abortive and growing colonies overlap (Fig 2 (a)), leading to substantial false positive as well as false-negative size-based classification in the presented data at relevant time points (7-11 days after irradiation, Fig 2(b)).