title: Effect of CT scan protocols on x-ray-induced DNA double-strand breaks in blood lymphocytes of patients undergoing coronary CT angiography.
abstract: OBJECTIVE
  To compare in vivo DNA lesions induced during helical and sequential coronary computed tomography angiography (CTA) and to evaluate the effect of CT parameters on double-strand break (DSB) levels.
  
  
  METHODS
  Thirty-six patients were examined with various CT protocols and modes (helical scan, n = 27; sequential scan, n = 9) either using a 64-slice dual-source or a 128-slice CT system. Blood samples were obtained before and 30 min after CT. Lymphocytes were isolated, stained against the phosphorylated histone variant γ-H2AX, and DSBs were visualised by using fluorescence microscopy.
  
  
  RESULTS
  DSB yields 30 min after CTA ranged from 0.04 to 0.71 per cell and showed a significant correlation to DLP (ρ = 0.81, p < 0.00001). Median DSB yield and median DLP were significantly lower after sequential compared to helical CT examinations (0.11 vs. 0.37 DSBs/cell and 249 vs. 958 mGy cm, p < 0.00001). Additional calcium scoring led to an increase in DLP (p = 0.15) and DSB levels (p = 0.04). DSB levels normalised to the DLP showed a significant correlation to the attenuation of the blood (ρ = 0.53, p = 0.01) and a negative correlation to the body mass index of the patients (ρ = -0.37, p = 0.06).
  
  
  CONCLUSIONS
  γ-H2AX immunofluorescence microscopy allows one to determine dose-related effects on x-ray-induced DSB levels and to consider individual factors which cannot be monitored by physical dose measurements.
authors.affiliation: Department of Radiology, University of Erlangen-Nürnberg, Maximiliansplatz 1, 91054, Erlangen, Germany. michael.kuefner@uk-erlangen.de
authors.forename: M A
authors.initials: MA
authors.lastname: Kuefner
authors.forename: S
authors.initials: S
authors.lastname: Grudzenski
authors.forename: J
authors.initials: J
authors.lastname: Hamann
authors.forename: S
authors.initials: S
authors.lastname: Achenbach
authors.forename: Michael
authors.initials: M
authors.lastname: Lell
authors.forename: K
authors.initials: K
authors.lastname: Anders
authors.forename: S A
authors.initials: SA
authors.lastname: Schwab
authors.forename: L
authors.initials: L
authors.lastname: Häberle
authors.forename: M
authors.initials: M
authors.lastname: Löbrich
authors.forename: M
authors.initials: M
authors.lastname: Uder
mesh_terms: D001681:Biological Assay / Q000379:methods*; D017023:Coronary Angiography / Q000379:methods*; D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage; D005260:Female; D006801:Humans; D008214:Lymphocytes / Q000502:physiology* / Q000528:radiation effects*; D008297:Male; D011829:Radiation Dosage; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D004247:DNA