PCC-ring induction in human lymphocytes exposed to gamma and neutron irradiation. J Radiat Res, advance publication 2006. Lloyd DC and Edwards AA. Chromosome aberrations in human lymphocytes: Effect of radiation quality, dose, and dose rate. In: Radiation

PCC-rings/Dose-effect curves/High doses radiation/Calyculin A/Human lymphocytes. In case of an accidental overexposure to ionizing radiation where the dose received by the victim is over 5 Gy, the conventional biological indicator of dose, the dicentric assay, does not provide an accurate enough dose measurement. A more appropriate technique is to measure ring chromosomes in stimulated lymphocytes. Dose-effect relationships were obtained by plotting the frequencies of Premature Chromo-some Condensation (PCC)-rings in PCC lymphocytes obtained by chemical induction with Calyculin A in vitro, irradiated with doses between 5 to 25 Gy. Cells were exposed either to neutron or to gamma rays and the corresponding dose effect curves are presented in this paper for the first time in literature. For the elaboration of these curves, 9 675 PCC cells in G1 G2 and M/A stages were analysed. The results were fitted to a lineal model in gamma irradiation up to 25 Gy. For neutron irradiation the data was fitted to a lineal model up to 10 Gy, and then dose saturation was observed. In conclusion, with this technique it is possible to set up dose effect curves up to 25 or 10 Gy according to the gamma or neutron radiation