title: γ-H2AX foci are increased in lymphocytes in vivo in young children 1 h after very low-dose X-irradiation: a pilot study.
abstract: BACKGROUND
  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.
  
  
  OBJECTIVE
  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.
  
  
  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.
  
  
  RESULTS
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: University of Hawaii Cancer Center, 1236 Lauhala St., Honolulu, HI, 96813, USA, hildahalm@earthlink.net.
authors.forename: Brunhild M
authors.initials: BM
authors.lastname: Halm
authors.forename: Adrian A
authors.initials: AA
authors.lastname: Franke
authors.forename: Jennifer F
authors.initials: JF
authors.lastname: Lai
authors.forename: Helen C
authors.initials: HC
authors.lastname: Turner
authors.forename: David J
authors.initials: DJ
authors.lastname: Brenner
authors.forename: Vatche M
authors.initials: VM
authors.lastname: Zohrabian
authors.forename: Robert
authors.initials: R
authors.lastname: DiMauro
mesh_terms: D004249:DNA Damage; D004307:Dose-Response Relationship, Radiation; D006657:Histones / Q000235:genetics* / Q000528:radiation effects*; D006801:Humans; D007223:Infant; D008214:Lymphocytes / Q000502:physiology* / Q000528:radiation effects*; D008297:Male; D010865:Pilot Projects; D011829:Radiation Dosage; D014057:Tomography, X-Ray Computed
chemical_list: C468783:H2AX protein, human; D006657:Histones
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