title: [Elimination of direct derivative of the projection data for image reconstruction based on hybrid filter in helical cone-beam CT].
abstract: OBJECTIVE
  We present an alternative approach for precise reconstruction of the images from helical cone-beam projections combining Hilbert filter and Ramp filter.
  
  
  METHODS
  Based on the Katsevich algorithm framework, the proposed algorithm combined the FDK-type algorithms and Katsevich algorithm for their respective advantages, to completely avoid the direct derivatives with respect to the coordinates on the detector plane.
  
  
  RESULTS
  The experimental results validated the accuracy of the new algorithm, and this approach significantly improved the resolution of the reconstructed images with much reduced artifacts.
  
  
  CONCLUSIONS
  The proposed reconstruction formula based on hybrid Hilbert-Ramp filter is an important development of Katsevich reconstruction formula, and the different forms of the Ramp filters can be designed to realize frequency modulation according to the actual clinical application.
authors.affiliation: School of Biomedical Engineering, Southern Medical University, Guangzhou 510515, China. jhma@fimmu.com
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Ma
authors.forename: Ling-Jian
authors.initials: LJ
authors.lastname: Chen
authors.forename: Gang
authors.initials: G
authors.lastname: Yan
authors.forename: Wu-Fan
authors.initials: WF
authors.lastname: Chen
mesh_terms: D000465:Algorithms; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D054894:Spiral Cone-Beam Computed Tomography / Q000379:methods*