title: Estimation of radiation exposure of retrospective gated and prospective triggered 128-slice triple-rule-out CT angiography.
abstract: BACKGROUND
  CT has become an important role in the differential diagnosis of acute chest pain to exclude an aortic dissection, pulmonary embolism and acute coronary artery syndrome. However, the additional radiation exposure is a cause of concern and dose saving strategies should be applied, if possible.
  
  
  OBJECTIVE
  To estimate effective dose of retrospective gated and prospective ECG-triggered triple-rule-out computed tomography angiography (TRO-CTA).
  
  
  METHODS
  An Alderson-Rando-phantom equipped with thermoluminescent dosimeters was used for dose measurements. Exposure was performed on a 128-slice single source scanner. The following scan parameters were used (retrospective ECG-gated): 120 kV, 190 mAs/rot., collimation 128x0.6 mm, rotation time 0.3 s. Protocols with a simulated heart rate (HR) of 60 and 100 bpm were performed using the standard ECG-pulsing as well as MinDose. Additionally, a prospective triggered TRO-CTA was acquired (HR 60 bpm).
  
  
  RESULTS
  The estimated effective dose of retrospective ECG-gated TRO-CTA ranged from 7.4-13.4 mSv and from 10.1-17.5 mSv for men and women, respectively. Due to radiosensitive breast tissue, women received a significant increased effective dose of up to 64.7% ± 0.03% (p = 0.028) compared to men. MinDose reduces radiation exposure of up to 33.0% ± 6.5% in comparison to standard ECG-pulsing (p < 0.001). The effective dose increased significantly with lower heart rates (p < 0.001). Prospective ECG-triggered TRO-CTA showed an effective dose of 5.9 mSv and 8.2 mSv for men and women, respectively. Compared to retrospective ECG-gated TRO-CTA a significant dose reduction was observed (p < 0.001).
  
  
  CONCLUSIONS
  Due to the significant different dose exposure, scan protocols should be specifically adapted in a patient- and problem-oriented manner.
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: Christoph
authors.initials: C
authors.lastname: Thomas
authors.forename: Markus
authors.initials: M
authors.lastname: Buchgeister
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: Claus D
authors.initials: CD
authors.lastname: Claussen
authors.forename: Martin
authors.initials: M
authors.lastname: Heuschmid
mesh_terms: D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D017023:Coronary Angiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D018709:Statistics, Nonparametric; D013819:Thermoluminescent Dosimetry; D014057:Tomography, X-Ray Computed / Q000379:methods*