title: Chest CT using spectral filtration: radiation dose, image quality, and spectrum of clinical utility.
abstract: OBJECTIVE
  To determine the radiation dose, image quality, and clinical utility of non-enhanced chest CT with spectral filtration.
  
  
  METHODS
  We retrospectively analysed 25 non-contrast chest CT examinations acquired with spectral filtration (tin-filtered Sn100 kVp spectrum) compared to 25 examinations acquired without spectral filtration (120 kV). Radiation metrics were compared. Image noise was measured. Contrast-to-noise-ratio (CNR) and figure-of-merit (FOM) were calculated. Diagnostic confidence for the assessment of various thoracic pathologies was rated by two independent readers.
  
  
  RESULTS
  Effective chest diameters were comparable between groups (P = 0.613). In spectral filtration CT, median CTDIvol, DLP, and size-specific dose estimate (SSDE) were reduced (0.46 vs. 4.3 mGy, 16 vs. 141 mGy*cm, and 0.65 vs. 5.9 mGy, all P < 0.001). Spectral filtration CT had higher image noise (21.3 vs. 13.2 HU, P < 0.001) and lower CNR (47.2 vs. 75.3, P < 0.001), but was more dose-efficient (FOM 10,659 vs. 2,231/mSv, P < 0.001). Diagnostic confidence for parenchymal lung disease and osseous pathologies was lower with spectral filtration CT, but no significant difference was found for pleural pathologies, pulmonary nodules, or pneumonia.
  
  
  CONCLUSIONS
  Non-contrast chest CT using spectral filtration appears to be sufficient for the assessment of a considerable spectrum of thoracic pathologies, while providing superior dose efficiency, allowing for substantial radiation dose reduction.
  
  
  CONCLUSIONS
  • Spectral filtration enables non-contrast chest CT with very high dose efficiency. • This approach reduces CTDI vol , DLP, and SSDE (effective chest diameter 28 cm). • Lung nodules, pneumonia, and pleural pathologies can be assessed with uncompromised confidence.
authors.affiliation: Institute for Clinical Radiology, University Hospital Munich, Marchioninistraße 15, 81377, Munich, Germany, franziska.braun@med.uni-muenchen.de.
authors.forename: Franziska M
authors.initials: FM
authors.lastname: Braun
authors.forename: Thorsten R C
authors.initials: TR
authors.lastname: Johnson
authors.forename: Wieland H
authors.initials: WH
authors.lastname: Sommer
authors.forename: Kolja M
authors.initials: KM
authors.lastname: Thierfelder
authors.forename: Felix G
authors.initials: FG
authors.lastname: Meinel
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008168:Lung / Q000000981:diagnostic imaging; D008171:Lung Diseases / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement / Q000379:methods*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*