LET dependence of cell death and chromatin-break induction in normal human cells irradiated by neon-ion beams.

We investigated the LET dependence of cell death and chromatin-break induction in normal human embryo cells irradiated by accelerated neon-ion beams. Neon-ion beams were generated by the Riken Ring Cyclotron (RRC) at the Institute of Physical and Chemical Research, Japan. Chromatin breaks were measured by counting the number of chromatin fragments detected by the premature chromosome condensation (PCC) technique. The results indicated that cell death and the induction of remaining chromatin breaks showed a qualitatively similar LET dependence. The LET RBE curves for both cell death and the induction of remaining chromatin breaks had a broad peak in the LET range of 120-300 keV/microm and steeply downward trend up to 340 keV/microm. These results suggest that there is a good correlation between cell death and the induction of remaining chromatin breaks by neon-ion beams with different LET values.