Chromosome Aberrations as a Biological Dosimeter

Abstract

The changes in human chromosomes following X-irradation of freshly-drawn blood in vitro were photographed and enumerated from 3-day-old cultures of leukocytes. Among the forms of radiation damage observed were abnormal numbers of chromosomes (aneuploidy, polyploidy, endoreduplication), fragmentation of chromosomes (chromatid- and chromosome-type deletions) and abnormal chromosomes formed (dicentrics, rings, and trans locations). The frequency-dose relationships were linear for aneuploidy and chromatid-type deletions; they were curvilinear (quadratic) for polyploidy, chromosome-type deletions and dicentric chromosomes. Trans locations and rings occurred rarely at exposures greater that 200 and 250 r, respectively. The coefficients of the yields of dicentric chromosomes and of total breaks were similar to those of others when based on data from exposures to 200 r and less. Possible applications of these results to the standardization of a "biological dosimeter" of radiation damage in man and their limitations were discussed.