INDUCTION OF CHROMOSOME-ABERRATIONS IN HUMAN-CELLS BY CHARGED-PARTICLES

Chromosome aberrations induced by high-energy charged particles in nor mal human lymphocytes and human fibroblasts have been investigated, Th e charged particles included 250 MeV/nucleon protons, 290 MeV/nucleon carbon ions and 1 GeV/nucleon iron ions. The energies of the charged p articles were higher than in most of the studies reported in the liter ature, Lymphocytes were stimulated to grow immediately after irradiati on, while fibroblasts were incubated at 37 degrees C for 24 h for repa ir, Chromosomes were collected at the first mitosis after irradiation and chromosome aberrations were scored using the fluorescence in situ hybridization (FISH) technique with a whole-chromosome 4 probe. Chromo some aberrations were classified as reciprocal exchanges, incomplete e xchanges, deletions and complex exchanges, The relative biological eff ectiveness (RBE) for each type of aberration was calculated by dividin g a dose of 4 Gy by the dose of the charged particles producing the sa me effect as 4 Gy of gamma rays. Results of this study showed that com plex aberrations have the highest RBE for radiation of high linear ene rgy transfer (LET) for human lymphocytes, but for fibroblasts, the gre atest effect was for incomplete exchanges. For both lymphocytes and fi broblasts, iron ions induced a similar fraction of aberrant cells. (C) 1997 by Radiation Research Society.