X-RAY BIOLOGICAL DOSIMETRY PERFORMED BY SELECTIVE PAINTING OF HUMAN-CHROMOSOME-1 AND HUMAN-CHROMOSOME-2

Fluorescence in situ hybridization with a cocktail of whole-chromosome probes, specific for human chromosomes 1 and 2, was performed to analyze the induction of translocations and dicentrics in human peripheral blood lymphocytes exposed to 100 KVp X-rays and cultured for 48 h. The dose-response curves for both aberration types were linear-quadratic, with similar coefficients, and after correction for genome content were a little lower than the dose-response curve for dicentrics established by conventional analysis. Three doses were also assessed after 76-h culture. The dicentric yield at 76 h was reduced compared with that at 48 h because of the existence of second and third division metaphases. The translocation yield did not reduce except at dr Gy. The frequency of cells containing both dicentrics and translocations suggested that their occurrence is not correlated. The importance of stating the scoring criteria and of specifying the different types of aberrations is stressed.