title: Automated Tube Voltage Selection for Radiation Dose Reduction in CT Angiography Using Different Contrast Media Concentrations and a Constant Iodine Delivery Rate.
abstract: OBJECTIVE
  The purpose of this study was to systematically investigate radiation dose reduction using automated tube voltage selection during CT angiography (CTA) and to evaluate the impact of contrast medium (CM) injection protocols on dose reduction.
  
  
  METHODS
  A circulation phantom containing the thoracic and abdominal vasculature was used. Four different concentrations of CM (iopromide 300 and 370 mg I/mL and iomeprol 350 and 400 mg I/mL) were administered while maintaining an identical iodine delivery rate (1.8 g I/s) and total iodine load (20.0 g). Three different scanning protocols for CTA of the thoracoabdominal aorta were used: protocol A, no dose modulation; protocol B, automated tube current modulation (CARE Dose4D); and protocol C, automated tube voltage selection (CARE kV). The dose-length product was recorded to calculate the effective dose. Attenuation values (in Hounsfield units), image noise levels, and signal-to-noise ratios (SNRs) in six predefined intravascular sites (three thoracic and three abdominal) were measured by two readers. All values were analyzed using the Kruskal-Wallis test and two-way ANOVA.
  
  
  RESULTS
  There was a significant reduction in the effective dose (in millisieverts) for protocols B (mean ± SD, 2.03 ± 0.1 mSv) and C (1.00 ± 0.0 mSv) compared with protocol A (4.34 ± 0.0 mSv). The dose was reduced by 53% for protocol B and by 77% for protocol C. No significant differences were found in the effective dose among the different CM injection protocols within the scanning protocols; all p values were > 0.05. The attenuation values and SNRs were comparable among all the different CM injection protocols; all p values were > 0.05.
  
  
  CONCLUSIONS
  A large radiation dose reduction (77%) can be achieved using automated tube voltage selection independent of the CM injection protocol.
authors.affiliation: 1 Department of Radiology, Maastricht University Medical Center, P. Debyelaan 25, PO Box 5800, 6202 AZ Maastricht, The Netherlands.|2 CARIM School for Cardiovascular Diseases, Maastricht University Medical Center, Maastricht, The Netherlands.
authors.forename: Madeleine
authors.initials: M
authors.lastname: Kok
authors.affiliation: 1 Department of Radiology, Maastricht University Medical Center, P. Debyelaan 25, PO Box 5800, 6202 AZ Maastricht, The Netherlands.|2 CARIM School for Cardiovascular Diseases, Maastricht University Medical Center, Maastricht, The Netherlands.
authors.forename: Casper
authors.initials: C
authors.lastname: Mihl
authors.affiliation: 1 Department of Radiology, Maastricht University Medical Center, P. Debyelaan 25, PO Box 5800, 6202 AZ Maastricht, The Netherlands.
authors.forename: Anna
authors.initials: A
authors.lastname: Seehofnerová
authors.affiliation: 1 Department of Radiology, Maastricht University Medical Center, P. Debyelaan 25, PO Box 5800, 6202 AZ Maastricht, The Netherlands.
authors.forename: Jakub
authors.initials: J
authors.lastname: Turek
authors.affiliation: 3 Bayer HealthCare, Contrast Media Research, Berlin, Germany.
authors.forename: Gregor
authors.initials: G
authors.lastname: Jost
authors.affiliation: 3 Bayer HealthCare, Contrast Media Research, Berlin, Germany.
authors.forename: Hubertus
authors.initials: H
authors.lastname: Pietsch
authors.affiliation: 4 Siemens AG, Healthcare Sector, Forchheim, Germany.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Haberland
authors.affiliation: 1 Department of Radiology, Maastricht University Medical Center, P. Debyelaan 25, PO Box 5800, 6202 AZ Maastricht, The Netherlands.|2 CARIM School for Cardiovascular Diseases, Maastricht University Medical Center, Maastricht, The Netherlands.
authors.forename: Joachim E
authors.initials: JE
authors.lastname: Wildberger
authors.affiliation: 2 CARIM School for Cardiovascular Diseases, Maastricht University Medical Center, Maastricht, The Netherlands.
authors.forename: Marco
authors.initials: M
authors.lastname: Das
mesh_terms: D001027:Aortography / Q000295:instrumentation / Q000379:methods*; D003287:Contrast Media / Q000008:administration & dosage*; D006801:Humans; D007472:Iohexol / Q000008:administration & dosage / Q000031:analogs & derivatives*; D007479:Iopamidol / Q000008:administration & dosage / Q000031:analogs & derivatives*; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*
chemical_list: D003287:Contrast Media; C057937:iomeprol; D007472:Iohexol; C038192:iopromide; D007479:Iopamidol
keywords: CT angiography; automated tube potential selection; contrast media; radiation exposure