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 i nduction in normal human embryo cells irradiated by accelerated neon-i on beams. Neon-ion beams were generated by the Riken Ring Cyclotron (R RC) at the Institute of Physical and Chemical Research, Japan. Chromat in 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 chro matin breaks showed a qualitatively similar LET dependence. The LET-RB E curves for both cell death and the induction of remaining chromatin breaks had a broad peak in the LET range of 120-300 keV/mu m and steep ly downward trend up to 340 keV/mu m. These results suggest that there is a good correlation between cell death and the induction of remaini ng chromatin breaks by neon-ion beams with different LET values.