Use of the DBD–FISH technique for detecting DNA breakage in response to high doses of X-rays

The aim of this study was to generate a dose–response curve using the DNA breakage detection–fluorescent in situ hybridization (DBD–FISH) test as a biomarker of initial genetic effects induced by high doses of X-rays. A dose–response curve was obtained by measuring the ex vivo responses to increasing doses (0–50 Gy) of X-rays in the peripheral blood lymphocytes of ten healthy donors. The overall dose–response curve was constructed using integrated density (ID; area × fluorescence intensity) as a measure of genetic damage induced by irradiation. The correlation coefficient was high ( r = 0.934, b 0 = 10.408, and b 1 = 0.094). One-way ANOVA with the Student–Newman–Keuls test for multiple comparisons showed significant differences among the average ln ID values according to dose. Our results suggest the usefulness of the DBD–FISH technique for measuring intrinsic individual cellular radio sensitivity ex vivo.