PURPOSE: To reduce beam hardening artifacts in CT in case of an unknown x-ray spectrum and unknown material properties. METHODS: The authors assume that the object can be segmented into a few materials with different attenuation coefficients, and parameterize the spectrum using a small number of energy bins. The corresponding unknown spectrum parameters and material attenuation values are estimated by minimizing the difference between the measured sinogram data and a simulated polychromatic sinogram. Three iterative algorithms are derived from this approach: two reconstruction algorithms IGR and IFR, and one sinogram precorrection method ISP. RESULTS: The methods are applied on real x-ray data of a high and a low-contrast phantom. All three methods successfully reduce the cupping artifacts caused by the beam polychromaticity in such a way that the reconstruction of each homogeneous region is to good accuracy homogeneous, even in case the segmentation of the preliminary reconstruction image is poor. In addition, the results show that the three methods tolerate relatively large variations in uniformity within the segments. CONCLUSIONS: We show that even without prior knowledge about materials or spectrum, effective beam hardening correction can be obtained.
PURPOSE: To reduce beam hardening artifacts in CT in case of an unknown x-ray spectrum and unknown material properties. METHODS: The authors assume that the object can be segmented into a few materials with different attenuation coefficients, and parameterize the spectrum using a small number of energy bins. The corresponding unknown spectrum parameters and material attenuation values are estimated by minimizing the difference between the measured sinogram data and a simulated polychromatic sinogram. Three iterative algorithms are derived from this approach: two reconstruction algorithms IGR and IFR, and one sinogram precorrection method ISP. RESULTS: The methods are applied on real x-ray data of a high and a low-contrast phantom. All three methods successfully reduce the cupping artifacts caused by the beam polychromaticity in such a way that the reconstruction of each homogeneous region is to good accuracy homogeneous, even in case the segmentation of the preliminary reconstruction image is poor. In addition, the results show that the three methods tolerate relatively large variations in uniformity within the segments. CONCLUSIONS: We show that even without prior knowledge about materials or spectrum, effective beam hardening correction can be obtained.
Authors: Ullrich Ebersberger; Francesco Tricarico; U Joseph Schoepf; Philipp Blanke; J Reid Spears; Garrett W Rowe; William T Halligan; Thomas Henzler; Fabian Bamberg; Alexander W Leber; Ellen Hoffmann; Paul Apfaltrer Journal: Eur Radiol Date: 2012-07-10 Impact factor: 5.315
Authors: Andreas M Bucher; Julian L Wichmann; U Joseph Schoepf; Christopher D Wolla; Christian Canstein; Andrew D McQuiston; Aleksander W Krazinski; Carlo N De Cecco; Felix G Meinel; Thomas J Vogl; Lucas L Geyer Journal: Eur Radiol Date: 2015-12-09 Impact factor: 5.315
Authors: Anne L Schafer; Galateia J Kazakia; Eric Vittinghoff; Lygia Stewart; Stanley J Rogers; Tiffany Y Kim; Jonathan T Carter; Andrew M Posselt; Courtney Pasco; Dolores M Shoback; Dennis M Black Journal: J Bone Miner Res Date: 2018-02-05 Impact factor: 6.741
Authors: A M Boers; I A Zijlstra; C S Gathier; R van den Berg; C H Slump; H A Marquering; C B Majoie Journal: AJNR Am J Neuroradiol Date: 2014-08-07 Impact factor: 3.825