Repair kinetics of DSB-foci induced by proton and helium ion microbeams of different energies

TL;DR

This study compares the induction and repair of DNA damage foci caused by proton and helium ion microbeams of different energies, revealing that LET alone may not fully characterize radiation quality and that protons may induce more persistent damage.

Contribution

It provides new insights into how different ion types and energies affect DNA damage repair kinetics, challenging the reliance on LET as the sole radiation quality parameter.

Findings

Persistent foci increase with LET but fraction does not

Protons produce more persistent foci than higher LET alpha particles

Disappearance of foci follows first order kinetics

Abstract

In this work, the induction and repair of radiation-induced 53BP1 foci were studied in human umbilical vein endothelial cells irradiated at the PTB microbeam with protons and {\alpha}-particles of different energies. The data were analyzed in terms of the mean number of 53BP1 foci induced by the different ion beams. The number of 53BP1 foci found at different times post-irradiation suggests that the disappearance of foci follows first order kinetics. The mean number of initially produced foci shows the expected increase with LET. The most interesting finding of this work is that the absolute number of persistent foci increases with LET but not their fraction. Furthermore, protons seem to produce more persistent foci as compared to {\alpha}-particles of even higher LET. This may be seen as experimental evidence that protons may be more effective in producing severe DNA lesions, as was already shown in other work, and that LET may not be the best suited parameter to characterize radiation quality