Chromosome Aberrations Induced by Different Kinds of Radiation and Their Usefulness as Biological Indicator of the Radiation Damage. Final Report for the Period 1 February 1978-31 January 1981

摘要

Human lymphocytes were irradiated immediately after sample collection. The lymphocytes were cultured, according to the Hungerford micromethod, for 52 hours. Colcemid for mitotic arrest at the metaphase was added 4 hours prior to the end of the culture period. 220 KV x-rays at dose-rate of 60 rads/min in the dose range of 0, 50, 100, 200, 300, 400 rads; Co-60 gamma-rays at dose-rate of 50 rads/min in the dose range 0, 50, 100, 200, 300, 400 rads, and fission neutrons of different energies and flux densities (from the Experimental Nuclear Reactor IRT-2000 in Sofia) in the dose range 0, 25, 50, 100, and 200 rads were used as sources. The following anomalies and parameters were analysed: chromatide and chromosome deletions, dicentrics and multicentrics, minutes, rings, total number of aberrations and total number of aberrant cells. The quantitative dose/anomaly relationship has been analysed by the least squares method using: Y=a+cD exp 2 , Y=a+bD, Y=bD/sup n/, and Y=a+bD+cD exp 2 as models where Y is the number of aberrations, D the dose in rads, and a, b, c, and n the equations coefficients. A functional relationship between the dose and the number of the structural chromosomal aberrations could be demonstrated. Low-LET radiations induced, by linear kinetics, chromosome deletions and increased the total number of aberrant cells and, by non-linear kinetics, the same induced dicentrics and multi-centrics, minutes, rings, and increased the total number of aberrations. Not all kinds of aberrations are fitted into the model Y=cD exp 2 . Two-break aberrations are best fitted into: Y=a+bD+cD exp 2 . High-LET radiations (e.g. fission neutrons) induced all kinds of aberrations according to Y=a+bD. The RBE values showed that Co-60 gamma radiation is 20% less effective than the 220 KV x-rays, and that RBE for fission neutrons varied from 1.8 at high doses to 5.0 at low doses. (Atomindex citation 12:634589)