PCC-rings dose effect curves in human lymphocytes exposed to gamma and neutron irradiation

Titre du congrès :BiodosEPR-2006 2nd International Conference on Biodosimetry and 7th International Symposium on ESR Dosimetry and Applications Ville du congrès :Bethesda Date du congrès :10/07/2006

The Prematurely Condensed Chromosomes method combines the possibilities of the efficiently premature chromosome condensation induction by the okadaic acid or the Calyculin A with the simplicity of the Giemsa staining. This method overcomes the three major problems of the conventional biological dosimetry by dicentric analysis at high doses, (i) the lymphopenia due to cell death reducing the number of lymphocytes available; (ii) the radio-induced cell cycle arrests causing low mitotic index. (iii) the dicentrics saturation at high doses. Therefore the mitotic index is low and the number of cells available to have a statistically significant result based on at least 100 cells is very difficult to achieve at high dose. In this paper, dose-effect curves for dose assessment for gamma and neutron high doses overexposures are presented. The dose range of the curves is from 5 Gy to 25 Gy. For the elaboration of these curves 9 676 PCC cells in G1 G2 and M/A stages were analyzed. The results were fitted to a lineal quadratic model in gamma irradiation and showed saturation starting from 20 Gy. For neutron irradiation the data was fitted to a lineal quadratic model up to 10 Gy, and then a markedly cell cycle arrest and saturation was observed. These curves are of particular interest for victims exposed to doses exceeding 5 Gy above which it is always very difficult to estimate a dose using the conventional technique