title: X-ray induced DNA double-strand breaks in coronary CT angiography: comparison of sequential, low-pitch helical and high-pitch helical data acquisition.
abstract: BACKGROUND
  Aim of this study was to compare DNA double-strand breaks (DSBs) in blood lymphocytes of patients undergoing high-pitch helical, low-pitch helical and sequential coronary CT angiography.
  
  
  RESULTS
  66 patients were examined with various scan protocols and modes (low-pitch helical scan: 100-120 kV, 320-438 mAs/rot, pitch 0.18-0.39, with or without ECG-pulsing, n=35; prospectively ECG-triggered high-pitch helical scan: 100-120 kV, 320-456 mAs/rotation, pitch 3.2-3.4, n=19; prospectively ECG-triggered sequential scan: 100-120 kV, 150-300 mAs or 320-370 mAs/rotation, n=12) either using a 64-slice or 128-slice dual-source CT or a 128-slice single source CT scanner. Blood samples were obtained before and 30 min after CT and DSBs were analyzed in isolated lymphocytes using γ-H2AX immunofluorescence microscopy. A significant increase of DSBs was measurable 30 min after CTA (range 0.01-0.71/cell). CT induced DSBs showed a significant correlation with the estimated effective dose (ρ=0.90, p<0.00001). Both prospectively ECG-triggered sequential (0.10 DSBs/cell, 176 mGy cm, p<0.00001) and high-pitch helical scan protocols (0.03 DSBs/cell, 109 mGy cm, p<0.00001) led to a significant reduction of median DLP and DSB levels compared to low-pitch helical scans (0.34 DSBs/cell, 828 mGy cm). A reduction of the tube voltage resulted in significantly lower whereas additional calcium scoring resulted in elevated DLP and DNA damages (p<0.05 each).
  
  
  CONCLUSIONS
  In coronary CTA, data acquisition protocols have a significant influence on the X-ray induced DSB levels. Using γ-H2AX immunofluorescence microscopy different scan modes in different CT generations can be compared concerning their biological impact.
authors.affiliation: Department of Radiology, University of Erlangen-Nürnberg, Maximiliansplatz 1, D-91054 Erlangen, Germany. michael.brand@uk-erlangen.de
authors.forename: Michael
authors.initials: M
authors.lastname: Brand
authors.forename: Matthias
authors.initials: M
authors.lastname: Sommer
authors.forename: Stephan
authors.initials: S
authors.lastname: Achenbach
authors.forename: Katharina
authors.initials: K
authors.lastname: Anders
authors.forename: Michael
authors.initials: M
authors.lastname: Lell
authors.forename: Markus
authors.initials: M
authors.lastname: Löbrich
authors.forename: Michael
authors.initials: M
authors.lastname: Uder
authors.forename: Michael A
authors.initials: MA
authors.lastname: Kuefner
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D055424:Cardiac-Gated Imaging Techniques / Q000009:adverse effects / Q000379:methods*; D003287:Contrast Media; D017023:Coronary Angiography / Q000009:adverse effects / Q000379:methods*; D003327:Coronary Disease / Q000000981:diagnostic imaging*; D053903:DNA Breaks, Double-Stranded / Q000528:radiation effects*; D005260:Female; D006801:Humans; D008214:Lymphocytes / Q000528:radiation effects*; D008297:Male; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D011829:Radiation Dosage; D018709:Statistics, Nonparametric; D036542:Tomography, Spiral Computed / Q000009:adverse effects / Q000379:methods*
chemical_list: D003287:Contrast Media