Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

Over the past years, several in vitro studies have been performed on DNA damage induced by soft X-rays, especially in the energy range below 50 keV. Radiation effects originating from such low-energy photons are relevant in the context of medical diagnostics, e.g. mammography, or of accidental exposure to scattered radiation. The present study was initiated to investigate the X-ray energy dependent induction of stable and unstable chromosomal aberrations in the human mammary epithelial cell line 184A1. Three colour fluorescence in situ hybridisation was applied to identify chromosomal damage in chromosomes 1, 8 and 17, induced by 10 kV or 25 kV soft X-rays as well as by 200 kV X-rays as a reference quality.
Based on dose dependencies in the range of 0.5 to 5 Gy, RBE values of 0.84 ± 0.09 and 1.45 ± 0.18 were found for stable translocations induced by 25 kV and 10 kV X-rays, respectively, using 200 kV X-rays as reference. Moreover, the analysis of the minimum number of breaks, as required to form the visible chromosomal damage, resulted in similar RBE values of 0.93 ± 0.07 for 25 kV X-rays and 1.25 ± 0.10 for 10 kV X-rays relative to 200 kV X-rays. In addition, non-DNA-proportional contributions of chromosomes 8 and 17 to the whole DNA damage and deviations from the expected 1:1 ratio of translocations and dicentrics were revealed for the mammary epithelial cell line 184A1.