In previous RENEB interlaboratory comparisons based on the manual scoring of dicentric chromosomes, a tendency for systematic overestimation for doses >
2.5 Gy was found. However, these exercises included only very few doses in the high dose range, and they were heterogeneous in terms of radiation quality and evaluation mode, and comparable only to a limited extent. Here, this presumed deviation was explored by investigating three doses >
2.5 Gy. Blood samples were irradiated (2.56, 3.41 and 4.54 Gy) using a