title: Estimation of radiation exposure of different dose saving techniques in 128-slice computed tomography coronary angiography.
abstract: OBJECTIVE
  To estimate the effective dose of cardiac CT with different dose saving strategies dependent on varying heart rates.
  
  
  METHODS
  For dose measurements, an Alderson-Rando-phantom equipped with thermoluminescent dosimeters was used. The effective dose was calculated according to ICRP 103. Exposure was performed on a 128-slice single source scanner providing a rotation time of 0.30s and standard protocols with 120 kV and 160 mAs/rot. Protocols were evaluated without ECG-pulsing, with two different ECG-pulsing techniques, and automated exposure control with a simulated heart rate of 60 and 100 beats per minute.
  
  
  RESULTS
  Depending on different dose saving techniques and heart rate, the effective whole-body dose of a cardiac scan ranged from 2.8 to 9.5 mSv and from 4.3 to 16.0 mSv for males and females, respectively. The radiation-sensitive breast tissue in the primary scan range results in an increased female dose of 66.7 ± 6.0%. Prospective triggering has the greatest potential to reduce the effective dose to 27.8%, compared to a comparable scan protocol with retrospective ECG-triggering with no ECG-pulsing. Furthermore, the heart rate influences the radiation exposure by increasing significantly at lower heart rates.
  
  
  CONCLUSIONS
  Due to this broad variability in radiation exposure of a cardiac CT, the radiologist and the CT technician should be aware of the different dose reduction strategies.
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Tuebingen, Hoppe-Seyler-Strasse 3, 72076 Tuebingen, Germany. dominik.ketelsen@med.uni-tuebingen.de
authors.forename: Dominik
authors.initials: D
authors.lastname: Ketelsen
authors.forename: Michael
authors.initials: M
authors.lastname: Fenchel
authors.forename: Markus
authors.initials: M
authors.lastname: Buchgeister
authors.forename: Christoph
authors.initials: C
authors.lastname: Thomas
authors.forename: Nadine
authors.initials: N
authors.lastname: Boehringer
authors.forename: Ilias
authors.initials: I
authors.lastname: Tsiflikas
authors.forename: Michael
authors.initials: M
authors.lastname: Kaempf
authors.forename: Roland
authors.initials: R
authors.lastname: Syha
authors.forename: Claus D
authors.initials: CD
authors.lastname: Claussen
authors.forename: Martin
authors.initials: M
authors.lastname: Heuschmid
mesh_terms: D000328:Adult; D000465:Algorithms; D001822:Body Burden; D017023:Coronary Angiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods*; D011874:Radiometry / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*