electron accelerator providing pulsed irradiation separated by time intervals of a second to a few minutes, the V. Favaudon’s group observed a tetraphasic, W-shaped time-dependent dose-response curve strongly dependent on the cell line and on the PARP status,suggesting again the influence of chromatin organization. Questions about synergy between these particular effects with HRS phenomenon (described in the section above) are of clinical interest. Since it is long known that time between split-dose conditions the chromatin recondensation and the DSB repair(see for instance), a better understanding of the dynamics of chromatin condensation/decondensation in the separticular but clinically relevant conditions would be therefore a very useful research axis.