Planar Proton Minibeam Irradiation Elicits Spatially Confined DNA Damage in a Human Epidermis Model

The study investigated the effects of proton minibeam radiotherapy (pMBRT) on DNA damage in a human epidermis model, focusing on the potential to reduce skin side effects by sparing healthy tissue. It was found that 66 µm minibeams caused severe DNA damage at dose peaks but spared surrounding tissue, with only 17% of cells exposed to high doses. DNA damage was largely repaired within 72 hours, although apoptotic cell death increased at 24 and 72 hours post-irradiation. Wider beams (408 and 920 µm) resulted in more widespread damage. The findings suggested that highly focused pMBRT could effectively reduce side effects in radiotherapy by confining DNA damage to targeted areas, thus preserving healthy tissue.