title: Reaching for better image quality and lower radiation dose in head and neck CT: advanced modeled and sinogram-affirmed iterative reconstruction in combination with tube voltage adaptation.
abstract: OBJECTIVE
  The aim of this study was to evaluate image quality and radiation dose in low-dose head and neck CT comparing two different commercially available iterative reconstruction algorithms: sinogram-affirmed iterative reconstruction (SAFIRE) and advanced modeled iterative reconstruction (ADMIRE) with fixed and automated tube voltage adaptation (TVA).
  
  
  METHODS
  CT examinations of 103 patients were analysed. 58 patients were examined on a single-source CT at fixed tube voltage of 120 kV and reconstructed with filtered back projection (FBP) and SAFIRE (Strength Level 3). 45 patients were examined in a single-source mode on a dual-source CT with automated TVA and reconstructed with FBP and ADMIRE (Strength Levels 2 and 3). Image noise was calculated in seven anatomical volumes of interest. Subjective evaluation of the CT images was performed using a four-grade scale.
  
  
  RESULTS
  Mean CT numbers of FBP and the corresponding iterative reconstruction did not differ significantly (p = 0.74-0.99). Image noise was lower with both iterative reconstruction techniques than with FBP (SAFIRE 3: -22.3%; ADMIRE 2: -14.9%; ADMIRE 3: -24.2%; all p < 0.05); hence, the signal-to-noise ratio and the contrast-to-noise values were higher. Subjective image quality revealed a more favourable result for the iterative reconstruction. ADMIRE 3 in combination with automated TVA showed 14.4% (p < 0.05) less image noise with a 7.5% lower radiation dose than SAFIRE 3 with fixed tube voltage.
  
  
  CONCLUSIONS
  Higher image quality at lower radiation dose can be achieved using ADMIRE in combination with automated TVA.
authors.affiliation: 1 Department of Radiology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Germany.
authors.forename: Andrea I
authors.initials: AI
authors.lastname: Schmid
authors.affiliation: 1 Department of Radiology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Germany.|2 Imaging Science Institute (ISI) Erlangen, Department of Radiology, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Uder
authors.affiliation: 1 Department of Radiology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Germany.|3 Department of Radiology and Nuclear Medicine, Klinikum Nürnberg, Germany, Paracelsus Medical University.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Lell
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D003287:Contrast Media; D005260:Female; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D058996:Quality Improvement; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media
keywords: computed tomography; head and neck; image quality enhancement; iterative reconstruction; radiation dose