title: Scan length adjustment of CT coronary angiography using the calcium scoring scan: effect on radiation dose.
abstract: OBJECTIVE
  The objective of our study was to prospectively investigate the effect of adjusting the scan length of CT coronary angiography using the calcium scoring images instead of the scout view with regard to radiation dose.
  
  
  METHODS
  One hundred twenty-five consecutive patients (mean age +/- SD, 62 +/- 10 years) undergoing both calcium scoring and CT coronary angiography were included in our study. The scan length of calcium scoring was planned on the scout view; the scan length of CT coronary angiography was planned on the axial images of the calcium scoring by identifying the origin of the left main artery and cardiac apex and adding 1 cm cranially and caudally. Effective radiation doses were calculated for CT coronary angiography using both scout view-derived and calcium scoring-derived scan lengths.
  
  
  RESULTS
  The scout view-derived scan length (mean +/- SD, 139 +/- 13 mm) was significantly greater than the calcium scoring-derived scan length (117 +/- 9 mm; p < 0.01). The average radiation dose was 0.8 +/- 0.3 mSv (range, 0.6-1.5 mSv) for calcium scoring and 9.0 +/- 0.6 mSv (range, 6.5-10.2 mSv) for CT coronary angiography. Using the scout view-derived scan length would have been associated with an effective radiation dose of 10.7 +/- 1.2 mSv (mean +/- SD) for CT coronary angiography, which is significantly higher than that using the calcium scoring-derived scan length (p < 0.05). The average difference between CT coronary angiography using a calcium scoring-derived scan length and that using a scout view-derived scan length was 1.7 +/- 0.9 mSv, corresponding to a radiation dose reduction of 16%. The average dose reduction when using a calcium scoring-derived instead of a scout view-derived scan length for CT coronary angiography-including the radiation dose of the calcium scoring scan-was 1.2 +/- 0.8 mSv (range, 0.1-2.7 mSv) (p < 0.05).
  
  
  CONCLUSIONS
  Adjustment of the scan length of CT coronary angiography using the images from calcium scoring instead of the scout view is feasible and is associated with a 16% reduction in radiation dose of dual-source CT coronary angiography.
authors.affiliation: Institute of Diagnostic Radiology, University Hospital Zurich, Raemistrasse 100, 8091 Zurich, Switzerland. sebastian.leschka@usz.ch
authors.forename: Sebastian
authors.initials: S
authors.lastname: Leschka
authors.forename: Chan-Hi
authors.initials: CH
authors.lastname: Kim
authors.forename: Stephan
authors.initials: S
authors.lastname: Baumueller
authors.forename: Paul
authors.initials: P
authors.lastname: Stolzmann
authors.forename: Hans
authors.initials: H
authors.lastname: Scheffel
authors.forename: Borut
authors.initials: B
authors.lastname: Marincek
authors.forename: Hatem
authors.initials: H
authors.lastname: Alkadhi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002114:Calcinosis / Q000000981:diagnostic imaging*; D003287:Contrast Media; D017023:Coronary Angiography / Q000379:methods*; D003327:Coronary Disease / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007472:Iohexol / Q000031:analogs & derivatives; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011829:Radiation Dosage; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media; D007472:Iohexol; C038192:iopromide