Leukocyte DNA Damage after Multi–Detector Row CT: A Quantitative Biomarker of Low-Level Radiation Exposure

Purpose: To prospectively determine if γH2AX (phosphorylated form of H2AX histone variant)-based visualization and quantification of DNA damage induced in peripheral blood mononuclear cells (PBMCs) can be used to estimate the radiation dose received by adult patients who undergo multidetector computed tomography (CT). Materials and Methods: After institutional review board approval and written informed patient consent were obtained, eight women and five men (mean age, 63.8 years) who would be undergoing chest-abdominal-pelvic CT or chest CT only were recruited. Venous blood samples obtained before scanning were exposed to different radiation doses in vitro and incubated for 5–30 minutes to obtain reference values of γH2AX focus yield. Additional blood samples were taken 5–30 minutes after CT. Leukocytes were isolated, fixed, and stained for γH2AX expression. The γH2AX focus yields were determined with fluorescence microscopy, and the radiation doses delivered during CT were estimated by comparing post-CT ...