Breakage of human interphase chromosomes by alpha particles and X-rays.
The technique of premature chromosome condensation (PCC) was used to compare the early formation of chromosome breaks in non-cycling HF19 human diploid fibroblasts when irradiated with slow alpha particles (3.2 MeV, 128 keV micron-1) or 250 kVP X-rays. For both radiations the production of PCC breaks increased approximately linearly with dose. The production coefficient for alpha particles was 12.5 +/- 0.6 per cent per Gy and for X-rays it was 5.8 +/- 0.2 per cell per Gy. Hence, the relative biological effectiveness (RBE) of the alpha particles was 2.16 +/- 0.13. This is smaller than reported values of the RBE for the production of chromosome-type exchange aberrations by slow alpha particles. This implies that there is a difference, spatial or qualitative, in the initial breaks produced by the densely ionizing alpha particle tracks and the more sparsely ionizing electron tracks from the X-rays.
Bedford
J S
JS
Department of Radiology and Radiation Biology, Colorado State University, Fort Collins 80523.
Goodhead
D T
DT
D000512:Alpha Particles; D002460:Cell Line; D002869:Chromosome Aberrations; D004171:Diploidy; D005347:Fibroblasts / Q000528:radiation effects; D006801:Humans; D007399:Interphase / Q000528:radiation effects*; D012062:Relative Biological Effectiveness