DOI: 10.1148/radiol.2421060171
Leukocyte DNA Damage after Multi–Detector Row CT: A Quantitative Biomarker of Low-Level Radiation Exposure1
Kai Rothkamm, Dipl Phys, Dr rer nat,
Sheena Balroop, MSc,
Jane Shekhdar, MSc,
Patricia Fernie, DCR(R) and
Vicky Goh, MRCP, FRCR
1 From the Department of Radiation Oncology & Biology, University of Oxford (K.R.), Gray Cancer Institute (K.R., S.B.); Department of Medical Physics (J.S.); and Paul Strickland Scanner Centre (P.F., V.G.), Mount Vernon Hospital, Rickmansworth Road, Northwood, Middlesex HA6 2JR, England. Received January 29, 2006; revision requested March 7; revision received April 5; final version accepted June 1. Funded by the Royal College of Radiologists/Society and College of Radiographers and the Gray Laboratory Cancer Research Trust.
Address correspondence to K.R. (e-mail: rothkamm{at}gci.ac.uk).
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Figure 1: Graph shows linear induction and similar yields of  H2AX foci in PBMCs and primary human fibroblasts (MRC-5) after in vitro x-ray irradiation. Mean numbers of foci per cell are shown. Error bars represent standard errors of the mean at analysis of 40–150 cells. The line is a linear fit to the data points for PBMCs exposed to x-rays at 150 kV.
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Figure 2: Graph shows similar time courses for loss of H2AX foci in PBMCs and primary human fibroblasts (MRC-5) after 0.5-Gy x-ray irradiation in vitro. Foci were counted at different times after in vitro exposure to x-rays at 240 kV. Mean numbers of foci per cell are shown. Error bars represent standard errors of the mean at analysis of 40–100 cells. The line is a guide for the eye.
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Figure 4: Graph shows radiation-induced formation and loss of H2AX foci in leukocytes in blood samples taken before CT scanning and irradiated in vitro with 0-, 20-, and 100-mGy x-rays and in leukocytes in blood samples taken after chest-abdominal-pelvic CT (CAP-CT) and chest CT only (C-CT). For each data point, 40–400 cells were scored. Error bars represent standard errors of the mean at analysis of the numbers of cells.
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Figure 5: Graph shows similar mean values of loss of radiation-induced H2AX foci in PBMCs after chest-abdominal-pelvic CT (CAP-CT) and chest CT only (C-CT) and after in vitro exposure to 20, 100, and 500 mGy of x-ray radiation. For each treatment group, the mean numbers of foci per cell were normalized to the yield measured 5 minutes after exposure. Error bars represent standard errors of the mean at analysis of 40–360 cells in one patient who underwent chest CT only and in one patient whose blood sample was irradiated at 500 mGy and at analysis of the data for two to eight patients who underwent chest-abdominal-pelvic CT and whose blood samples were irradiated at 20 and 100 mGy.
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Figure 6: Graph shows H2AX yield–based calculations of radiation doses delivered during chest-abdominal-pelvic CT in patients 1–11 and during chest CT only in patient 13 that are consistent with phantom dosimetry measurements. A = mean value for patients 1–11. Error bars represent standard errors of the mean at analysis of 50–360 cells; error bar for A represents standard error of the mean of values for patients 1–11.
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Copyright © 2007 by the Radiological Society of North America.
