Low-dose hypersensitivity of V79 cells under exposure to γ-rays and 4 He ions of different energies: survival and chromosome aberrations

PURPOSE: To examine the low-dose sensitivity of V79 cells under exposure to gamma-rays and 4He ions of different energies. MATERIALS AND METHODS: Cell survival and cytogenetic analysis using the Giemsa technique were studied following irradiation to doses of 0-3 Gy at the INFN-LNL facilities. RESULTS: Low-dose hyper-radiosensitivity (HRS) of V79 was demonstrated after irradiation with gamma-rays and alpha-particles of various linear energy transfers (LET) (58.9, 79.3 and 101.7 keV microm(-1)). Cytogenetic analysis showed an LET dependence of aberrations at a dose of 1Gy; the frequency of chromatid fragments appeared to vary with the number of alpha-particles traversing the cell nucleus. The results of both studies fit together to give a better understanding of so-called 'induced radioresistance' phenomenon. CONCLUSIONS: The mechanism of induced cellular radioresistance appears to be initiated after a certain amount of energy is deposited in the cell nucleus. This amount depends on both radiation quality and the number of particles traversing the cell.