This supplement brings together the contributions of 46 eminent international experts in research related to radiation medicine and radiobiology.

Several large studies have been conducted and it is timely to analyse biological effects as a function of time and daily exposure dose level for both rapid and slow cell renewal systems (hemopoiesis, skin, but also connective tissue, endothelial cells etc.). Recent advances in molecular pathology, cytogenetics, cell system physiology and biomathmatics are paving the way for an advanced approach to determining the mechanisms of tolerance.