DOSIMETRY FROM CHROMOSOME ABERRATION COUNTS IN BLOOD-LYMPHOCYTES

The frequency of unstable chromosome aberrations (dicentrics, acentric rings and fragments) in peripheral lymphocytes can be used as a biological dosimeter in case of real or suspected exposure. This operational methods has now a forensic value. The radiosensitivity of in vivo or in vitro irradiated lymphocytes being the same, the dose-effect relationships obtained after in vitro irradiation of blood samples can therefore be used. The post-irradiation delay, during which the amount of aberrations in peripheral lymphocytes remains a good representation of the true radiation-induced damage, is dependent on the exposure conditions. Following whole-body acute exposure, aberrations are remaining fairly at the same level during several weeks, even several months. Following heterogeneous or partial fractionated protracted exposure, they decrease more quickly, which results in an under-estimate of the truly radiation induced damage. A method based on the distribution of acentric fragments in cells with or without dicentrics or rings makes this dosimetry possible even after the decrease of the frequency of aberrations in peripheral lymphocytes. This method requiring the analysis of individualized cells in metaphasis, increases the post-exposure delay of use of such a dosimeter.