title: Low-dose CT imaging of a total hip arthroplasty phantom using model-based iterative reconstruction and orthopedic metal artifact reduction.
abstract: OBJECTIVE
  To compare quantitative measures of image quality, in terms of CT number accuracy, noise, signal-to-noise-ratios (SNRs), and contrast-to-noise ratios (CNRs), at different dose levels with filtered-back-projection (FBP), iterative reconstruction (IR), and model-based iterative reconstruction (MBIR) alone and in combination with orthopedic metal artifact reduction (O-MAR) in a total hip arthroplasty (THA) phantom.
  
  
  METHODS
  Scans were acquired from high- to low-dose (CTDIvol: 40.0, 32.0, 24.0, 16.0, 8.0, and 4.0 mGy) at 120- and 140- kVp. Images were reconstructed using FBP, IR (iDose4level 2, 4, and 6) and MBIR (IMR, level 1, 2, and 3) with and without O-MAR. CT number accuracy in Hounsfield Units (HU), noise or standard deviation, SNRs, and CNRs were analyzed.
  
  
  RESULTS
  The IMR technique showed lower noise levels (p < 0.01), higher SNRs (p < 0.001) and CNRs (p < 0.001) compared with FBP and iDose4in all acquisitions from high- to low-dose with constant CT numbers. O-MAR reduced noise (p < 0.01) and improved SNRs (p < 0.01) and CNRs (p < 0.001) while improving CT number accuracy only at a low dose. At the low dose of 4.0 mGy, IMR level 1, 2, and 3 showed 83%, 89%, and 95% lower noise values, a factor 6.0, 9.2, and 17.9 higher SNRs, and 5.7, 8.8, and 18.2 higher CNRs compared with FBP respectively.
  
  
  CONCLUSIONS
  Based on quantitative analysis of CT number accuracy, noise values, SNRs, and CNRs, we conclude that the combined use of IMR and O-MAR enables a reduction in radiation dose of 83% compared with FBP and iDose4in the CT imaging of a THA phantom.
authors.affiliation: Department of Radiology, Academic Medical Center, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands. r.h.wellenberg@amc.uva.nl.
authors.forename: R H H
authors.initials: RH
authors.lastname: Wellenberg
authors.affiliation: Department of Radiology, Isala, Zwolle, The Netherlands.
authors.forename: M F
authors.initials: MF
authors.lastname: Boomsma
authors.affiliation: Department of Radiology, Isala, Zwolle, The Netherlands.
authors.forename: J A C
authors.initials: JA
authors.lastname: van Osch
authors.affiliation: Philips Medical Systems, Brussels, Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Vlassenbroek
authors.affiliation: Philips Medical Systems, Eindhoven, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Milles
authors.affiliation: Department of Innovation and Science, Isala, Zwolle, The Netherlands.
authors.forename: M A
authors.initials: MA
authors.lastname: Edens
authors.affiliation: Department of Radiology, Academic Medical Center, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
authors.forename: G J
authors.initials: GJ
authors.lastname: Streekstra
authors.affiliation: MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands.
authors.forename: C H
authors.initials: CH
authors.lastname: Slump
authors.affiliation: Department of Radiology, Academic Medical Center, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Maas
mesh_terms: D019644:Arthroplasty, Replacement, Hip; D016477:Artifacts; D006621:Hip Joint / Q000000981:diagnostic imaging; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008670:Metals; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D008670:Metals
keywords: Computed tomography; IMR; Metal artifacts; Model-based iterative reconstruction; O-MAR; Quantitative analysis; Radiation dose reduction; Total hip arthroplasty phantom