title: Aortic Valve and Thoracic Aortic Calcification Measurements: How Low Can We Go in Radiation Dose?
abstract: OBJECTIVE
  This study aimed to determine the lowest radiation dose and iterative reconstruction level(s) at which computed tomography (CT)-based quantification of aortic valve calcification (AVC) and thoracic aortic calcification (TAC) is still feasible.
  
  
  METHODS
  Twenty-eight patients underwent a cardiac CT and 20 patients a chest CT at 4 different dose levels (routine dose and approximately 40%, 60%, and 80% reduced dose). Data were reconstructed with filtered back projection, 3 iDose levels, and 3 iterative model-based reconstruction levels. Two observers scored subjective image quality. The AVC and TAC were quantified using mass and compared to the reference scan (routine dose reconstructed with filtered back projection).
  
  
  RESULTS
  In cardiac CT at 0.35 mSv (60% reduced), all scans reconstructed with iDose (all levels) were diagnostic, calcification detection errors occurred in only 1 patient, and there were no significant differences in mass scores compared to the reference scan. Similar results were found for chest CT at 0.48 mSv (75% reduced) with iDose levels 4 and 6 and iterative model reconstruction levels 1 and 2.
  
  
  CONCLUSIONS
  Iterative reconstruction enables AVC and TAC quantification on CT at submillisievert dose.
authors: From the Departments of *Radiology, †Pulmonary Diseases, and ‡Cardiology, University Medical Center Utrecht, Utrecht; and §Department of Radiology, Erasmus Medical Center, Rotterdam, the Netherlands.
authors: Robbert Willem
authors: RW
authors: van Hamersvelt
authors: Annemarie M
authors: AM
authors: den Harder
authors: Martin J
authors: MJ
authors: Willemink
authors: Arnold M R
authors: AM
authors: Schilham
authors: Jan-Willem J
authors: JJ
authors: Lammers
authors: Hendrik M
authors: HM
authors: Nathoe
authors: Ricardo P J
authors: RP
authors: Budde
authors: Tim
authors: T
authors: Leiner
authors: Pim A
authors: PA
authors: de Jong
mesh_terms: D000368:Aged; D001013:Aorta, Thoracic / Q000000981:diagnostic imaging*; D001021:Aortic Valve / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D000069079:Radiation Exposure / Q000032:analysis / Q000517:prevention & control*; D011835:Radiation Protection / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D061205:Vascular Calcification / Q000000981:diagnostic imaging*