γ-H2AX foci are increased in lymphocytes in vivo in young children 1 h after very low-dose X-irradiation: a pilot study
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Computed tomography (CT) is an imaging modality involving ionizing radiation. The presence of γ-H2AX foci after low to moderate ionizing radiation exposure has been demonstrated; however it is unknown whether very low ionizing radiation exposure doses from CT exams can induce γ-H2AX formation in vivo in young children.
To test whether very low ionizing radiation doses from CT exams can induce lymphocytic γ-H2AX foci (phosphorylated histones used as a marker of DNA damage) formation in vivo in young children.
Materials and methods
Parents of participating children signed a consent form. Blood samples from three children (ages 3–21 months) undergoing CT exams involving very low blood ionizing radiation exposure doses (blood doses of 0.22–1.22 mGy) were collected immediately before and 1 h post CT exams. Isolated lymphocytes were quantified for γ-H2AX foci by a technician blinded to the radiation status and dose of the patients. Paired t-tests and regression analyses were performed with significance levels set at P < 0.05.
We observed a dose-dependent increase in γ-H2AX foci post-CT exams (P = 0.046) among the three children. Ionizing radiation exposure doses led to a linear increase of foci per cell in post-CT samples (102% between lowest and highest dose).
We found a significant induction of γ-H2AX foci in lymphocytes from post-CT samples of three very young children. When possible, CT exams should be limited or avoided by possibly applying non-ionizing radiation exposure techniques such as US or MRI.
KeywordsChildren Radiation dose Lymphocytic γ-H2AX foci formation Computed tomography
We wish to thank the children and their parents who participated in the study. We would also like to thank Mr. Ronald Frick, MS, from the Gamma Corp. for his assistance in the CT parameters and calculations and Lynn Wilkens, PhD, for her statistical evaluation assistance. This study was funded by the University of Hawai’i Cancer Center Developmental Fund and the National Institute of Allergy and Infectious Diseases U19 AI067773 with the two senior authors (B.M.H and A.A.F.) as co-principal investigators and both contributing equally to this manuscript.
Conflicts of interest
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