title: Radiation exposure and image quality in staged low-dose protocols for coronary dual-source CT angiography: a randomized comparison.
abstract: OBJECTIVE
  To evaluate staged low-dose approaches for coronary CT angiography (CTA) in which a standard sequence was added if the low-dose sequence did not allow reliable rule-out of coronary stenosis.
  
  
  METHODS
  A total of 176 consecutive patients referred for dual-source CTA were randomized to three protocols: group 1 using prospective ECG-triggering (100 kV, 330 mAs), group 2 a retrospectively gated "MinDose" sequence (100 kV, 330 mAs) and group 3 a standard spiral sequence (120 kV, 400 mAs). If image quality in low-dose groups 1 or 2 was non-diagnostic, an additional standard CT examination (as in group 3) was performed.
  
  
  RESULTS
  Non-diagnostic image quality was found in 11/56, 4/55, and 2/65 patients (46/896, 4/880 and 3/1,040 coronary segments) in groups 1, 2 and 3, respectively. Median (interquartile ranges) volumes of contrast material, CTDI(vol), DLP and effective dose for low-dose groups 1 and 2 and for standard group 3 were 92.5 (11.3), 75.0 (2.5) and 75.0 (9.0) ml; 8.0 (1.4), 16.8 (4.8) and 48.1 (14.2) mGy; 108.0 (27.3), 246.0 (93.0) and 701.0 (207.8) mGy cm; and 1.5 (0.4), 3.4 (1.3) and 9.8 (2.9) mSv, respectively.
  
  
  CONCLUSIONS
  A staged coronary CTA protocol with an initial low-dose approach and addition of a standard sequence--should image quality be too low--can lead to a substantial reduction in radiation exposure.
authors.affiliation: Department of Internal Medicine 2, University of Erlangen, Ulmenweg 18, 91054, Erlangen, Germany. tobias.pflederer@uk-erlangen.de
authors.forename: Tobias
authors.initials: T
authors.lastname: Pflederer
authors.forename: Josy
authors.initials: J
authors.lastname: Jakstat
authors.forename: Mohamed
authors.initials: M
authors.lastname: Marwan
authors.forename: Tiziano
authors.initials: T
authors.lastname: Schepis
authors.forename: Sven
authors.initials: S
authors.lastname: Bachmann
authors.forename: Axel
authors.initials: A
authors.lastname: Kuettner
authors.forename: Katharina
authors.initials: K
authors.lastname: Anders
authors.forename: Michael
authors.initials: M
authors.lastname: Lell
authors.forename: Gerd
authors.initials: G
authors.lastname: Muschiol
authors.forename: Dieter
authors.initials: D
authors.lastname: Ropers
authors.forename: Werner G
authors.initials: WG
authors.lastname: Daniel
authors.forename: Stephan
authors.initials: S
authors.lastname: Achenbach
mesh_terms: D000368:Aged; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D003287:Contrast Media; D017023:Coronary Angiography / Q000379:methods*; D003327:Coronary Disease / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D007472:Iohexol / Q000031:analogs & derivatives; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol; C038192:iopromide