title: Computed tomography to diagnose coronary artery disease: a reduction in radiation dose increases applicability.
abstract: OBJECTIVE
  To assess the effects of dose-saving algorithms on the radiation dose in an established computed tomography coronary angiography (CTCA) clinical service.
  
  
  METHODS
  A 3 year retrospective analysis of all patients attending for a clinically indicated CTCA was performed. The effective dose was calculated using a cardiac-specific conversion factor [0.028 mSv(mGy·cm)(-1)]. Patients were stratified by the advent of new scanning technology and dose-saving protocols.
  
  
  RESULTS
  Between September 2007 and August 2010, 1736 examinations were performed. In the first 6 months, 150 examinations were performed with a mean effective dose of 29.6 mSv (99% CI 26.6-33 mSv). In March 2008 prospective electrocardiogram (ECG) gating was installed; reducing the effective dose to 13.6 mSv (99% CI 12.5-14.9 mSv). In March 2009, the scanner parameters were set to a minimal exposure time and 100 kV in patients with a body mass index (BMI) of <30. This reduced the mean dose to 7.4 mSv (99% CI 6.8-8 mSv). For the final six months the mean radiation dose for a cardiac scan was 5.9 mSv (99% CI 5.4-6.5 mSv) this figure incorporates all examinations performed irrespective of the protocol used.
  
  
  CONCLUSIONS
  With the implementation of evidence-based protocols, the effective dose from cardiac CT has significantly reduced. As CTCA services develop dose-saving algorithms should be adopted to keep the radiation dose as low as reasonably practical.
authors: Institute of Biomedical & Clinical Science, Peninsula College of Medicine & Dentistry, NIHR Clinical Research Facility, University of Exeter, Exeter, UK. Oliver.gosling@pms.ac.uk
authors: O
authors: O
authors: Gosling
authors: G
authors: G
authors: Morgan-Hughes
authors: S
authors: S
authors: Iyengar
authors: W
authors: W
authors: Strain
authors: R
authors: R
authors: Loader
authors: A
authors: A
authors: Shore
authors: C
authors: C
authors: Roobottom
mesh_terms: D000465:Algorithms; D015992:Body Mass Index; D017023:Coronary Angiography / Q000379:methods; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D004562:Electrocardiography / Q000379:methods; D006801:Humans; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D012189:Retrospective Studies; D036542:Tomography, Spiral Computed / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods*