In the last 15 years a growing interest in the biological effects induced by low doses of ionizing radiation has arisen in the scientific community, due to an increasing number of experimental evidences showing a plethora of
non-linear effects occurring after low-dose irradiations. In particular, hyper-radiosensitivity and induced radioresistance (HRS/IRR) have been reported after exposure to low- and high-LET radiation, in human (normal and tumoural) and other mammalian cells in vitro. In this framework, Chinese hamster V79 cells, human primary fibroblasts (HFFF2) and murine embryonic fibroblasts (MEFs) were irradiated with broadbeams of protons in the dose range 0.1–5.0Gy and at 1 Gy/min dose-rate. Cellular
response has been evaluated in terms of cell survival, micronuclei induction, chromosomal aberrations and telomere length alterations. For comparison purpose, the same
end-points were studied after X/γ-rays irradiation
