title: Radiation dose estimates from cardiac multislice computed tomography in daily practice: impact of different scanning protocols on effective dose estimates.
abstract: BACKGROUND
  Multislice computed tomography angiography (CTA) is a promising technology for imaging patients with suspected coronary artery disease. Compared with 16-slice CTA, the improved spatial and temporal resolution of 64-slice CTA (0.6- versus 1.0-mm slice thickness and 330- versus 420-ms gantry rotation time) is associated with an increase in radiation dose. The objective of this retrospective investigation was to compare the estimated dose received during 16- and 64-slice CTA in daily practice and to investigate the impact of different scan protocols on dose and image quality.
  
  
  RESULTS
  Radiation dose was estimated for 1035 patients undergoing coronary CTA. Scanning algorithms with and without an ECG-dependent dose modulation and with a reduced tube voltage were investigated on dose estimates and image quality. In the entire patient cohort, radiation dose estimates were 6.4+/-1.9 and 11.0+/-4.1 mSv for 16- and 64-slice CTA, respectively (P<0.01). The reduction in radiation dose estimates ranged between 37% and 40% and between 53% and 64% with the use of ECG-dependent dose modulation and with the combined use of the dose modulation and a reduced tube voltage, respectively. The reduction in dose estimates was not associated with a reduction in diagnostic image quality as assessed by the signal-to-noise ratio and by the frequency of coronary segments with diagnostic image quality.
  
  
  CONCLUSIONS
  The increase in spatial and temporal resolution with 64-slice CTA is associated with an increased radiation dose for coronary CTA. Dose-saving algorithms are very effective in reducing radiation exposure and should be used whenever possible.
authors.affiliation: Klinik für Herz- und Kreislauferkrankungen, Deutsches Herzzentrum München, Klinik an der TU München, Munich, Germany. hausleiter@dhm.mhn.de
authors.forename: Jörg
authors.initials: J
authors.lastname: Hausleiter
authors.forename: Tanja
authors.initials: T
authors.lastname: Meyer
authors.forename: Martin
authors.initials: M
authors.lastname: Hadamitzky
authors.forename: Ester
authors.initials: E
authors.lastname: Huber
authors.forename: Maria
authors.initials: M
authors.lastname: Zankl
authors.forename: Stefan
authors.initials: S
authors.lastname: Martinoff
authors.forename: Adnan
authors.initials: A
authors.lastname: Kastrati
authors.forename: Albert
authors.initials: A
authors.lastname: Schömig
mesh_terms: D000368:Aged; D000465:Algorithms; D002985:Clinical Protocols; D017023:Coronary Angiography / Q000379:methods / Q000592:standards; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods* / Q000592:standards