THE EFFECTIVENESS OF HIGH-ENERGY NEON IONS IN PRODUCING CHROMOSOMAL-ABERRATIONS IN HUMAN-LYMPHOCYTES

This paper presents the results of the observation of chromosomal aber rations in human lymphocytes following irradiation by 189 MeV Ne-20 io ns. Dicentrics were observed at the first metaphase and chromosomal br eaks at early interphase using the premature chromosome condensation t echnique (PCC). Comparison of these measurements with previous work wi th low LET radiation, produced RBE(m) values of 0.3 and 0.6 for dicent rics at metaphase and for breaks in early interphase, respectively. Re cently published work on the repair of double strand breaks using the PCC technique shows that following X irradiation, the dicentric yield does not alter with repair time but the breaks decrease with repair ti me with a time constant in the region of 1 or 2 h. More recently publi shed data in which cultures of mixed irradiated and unirradiated cells were scored for both dicentrics at metaphase and breaks at early inte rphase show that interphase death affects the dicentric yield at metap hase but not the break yield at early interphase. These observations p lace restrictions on the acceptability of models of radiation action.