Constructing a 2B calibration curve for retrospective dose reconstruction

For the purposes of an EC retrospective dose reconstruction programme of exposed persons in the Mayak region of the South Urals, it was necessary to construct a low dose rate gamma calibration curve for potentially transmissible chromosome-type aberrations detectable by FISH chromosome painting. Isolated human peripheral blood lymphocytes from four donors were irradiated in vitro with a range of Cs-137 gamma rays and cultured to first post-radiation mitosis. After standard checks for second-division contamination, fixed material was distributed to four participating laboratories where cytological preparations were made, chromosomes I, 4 and 8 plus all centrometres were stained using an agreed multicolour FISH protocol, and all types of aberrations scored with both S&S and PAINT nomenclatures. This paper describes how the apparently transmissible aberration types (predominantly reciprocal translocations; SBS 2B) were selected and corrected for non-transmissible pseudosimples and other hidden complexes to construct a useable calibration curve. some space is given to the statistical methodology developed to estimates.