title: Reduction of half-scan shading artifact based on full-scan correction.
abstract: OBJECTIVE
  Temporal studies (such as blood perfusion) commonly are used to measure function. Radiation dosage is a primary limiting factor for these scans. Half-scan reconstruction can decrease dosage and improve temporal resolution, but is not viable for quantitative studies because of shading artifact. We propose a method for identifying the artifact and minimizing its effect.
  
  
  METHODS
  It is possible to measure the shading artifact by producing both a full-scan and a half-scan reconstruction from the same projection data. A correlation was shown between the subset of data used for reconstruction and per-pixel variation. Furthermore, this variation can be parameterized by only the center angle of the projection data. By performing a single full-scan acquisition, it is possible to generate many half-scan reconstructions and measure the artifact; then future half-scan acquisitions can be corrected.
  
  
  RESULTS
  The artifact is caused by the inhomogeneity in the object being scanned. Before correction, the root mean square error between the half-scan reconstruction and the full-scan is 41.0. After correction, the error is decreased to 10.7, or 26% of the original value.
  
  
  CONCLUSIONS
  We present a method that can measure and correct for object-dependent half-scan shading artifact. This can enable half-scan reconstruction for use in quantitative temporal studies.
authors.affiliation: Department of Radiology, University of Iowa, College of Medicine, 200 Hawkins Drive, Iowa City, IA 52242,USA.
authors.forename: John Arbash
authors.initials: JA
authors.lastname: Meinel
authors.forename: Eric
authors.initials: E
authors.lastname: Hoffman
authors.forename: Anne
authors.initials: A
authors.lastname: Clough
authors.forename: Ge
authors.initials: G
authors.lastname: Wang
mesh_terms: D000465:Algorithms; D016477:Artifacts; D006801:Humans; D007091:Image Processing, Computer-Assisted; D019047:Phantoms, Imaging; D014057:Tomography, X-Ray Computed