title: Radiation dose threshold for coronary artery calcium score with MDCT: how low can you go?
abstract: OBJECTIVE
  To evaluate the lowest radiation exposure threshold at which coronary calcium scoring (CCS) remains accurate.
  
  
  METHODS
  A prospective study of 43 consecutive eligible patients referred for CCS underwent imaging in accordance with the manufacturer's recommended protocol. Dedicated software was used to generate 8 series of images simulating tube currents ranging from 20 to 300 mA. These images were randomised and read in blinded fashion to determine the lowest tube current at which the CCS remained accurate. The minimum mA was correlated with 6 different patients' biometric parameters: bodyweight, body mass index, AP and lateral thoracic diameters, average thoracic diameter and the scout attenuation coefficient (SAC). The 95% confidence interval for each parameter was used to calculate tube current threshold levels and hence stratified CCS protocols were derived.
  
  
  RESULTS
  Spearman's correlation coefficients of the minimum tube current for the 6 parameters were: 0.66, 0.63, 0.65, 0.74, 0.77 and 0.86 respectively (p < 0.001). SAC offered the largest potential reduction in mean effective dose from 1.86 mSv to 0.88 mSv.
  
  
  CONCLUSIONS
  CCS with at least 50% reduction in radiation exposure and below 1 mSv is feasible if CT scout projections are utilised effectively.
authors.affiliation: Radiology Department, East Lancashire Hospitals NHS Trust, Blackburn, UK. tomnewton30@gmail.com
authors.forename: Tom D
authors.initials: TD
authors.lastname: Newton
authors.forename: Hatem
authors.initials: H
authors.lastname: Mehrez
authors.forename: Kelly
authors.initials: K
authors.lastname: Wong
authors.forename: Ravi
authors.initials: R
authors.lastname: Menezes
authors.forename: Bernd J
authors.initials: BJ
authors.lastname: Wintersperger
authors.forename: Andrew
authors.initials: A
authors.lastname: Crean
authors.forename: Elsie
authors.initials: E
authors.lastname: Nguyen
authors.forename: Narinder
authors.initials: N
authors.lastname: Paul
mesh_terms: D000328:Adult; D000368:Aged; D000886:Anthropometry / Q000379:methods; D002114:Calcinosis / Q000473:pathology*; D002118:Calcium / Q000032:analysis*; D003331:Coronary Vessels / Q000473:pathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010641:Phenotype; D011446:Prospective Studies; D011829:Radiation Dosage; D011835:Radiation Protection; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D002118:Calcium