The λ-MLEM Algorithm: An Iterative Reconstruction Technique for Metal Artifact Reduction in CT Images
Filtered backprojection (FBP) is an inadequate method to cope with inconsistencies in Radon space and, consequently, leads to artifacts in reconstructed CT images. A solution to this problem is given by statistical reconstruction methods like the Maximum-Likelihood Expectation-Maximization (MLEM) algorithm. The advantage of MLEM is that it allows to weight raw projection data during reconstruction. The method presented here consists of two steps. In a first step, inconsistent data in the Radon space were bridged using a directional interpolation scheme. Since these surrogate data are contaminated with residual inconsistencies, in a second step, the image is reconstructed using a weighted MLEM algorithm. In this work, the modified MLEM algorithm for metal artifact reduction in CT is presented for clinical hip prosthesis data. On the basis of image entropy the reconstruction success is evaluated.
KeywordsSurrogate Data Metal Artifact Metal Object Metal Artifact Reduction Iterative Reconstruction Technique
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- 2.W. A. Kalender, R. Hebel, and J. Ebersberger, Reduction of CT artifacts caused by metallic implants, Radiology 164, 576, 1987.Google Scholar
- 4.M. Bertalmio, G. Sapira, Image Inpainting, Computer Graphics SIGGRAPH2000, 417, 2000.Google Scholar
- 6.M. Oehler and T. M. Buzug, CT Artifact Reduction with an Iterative Maximum Likelihood Approach, in: S. Weber et al. (Eds.), Computer Aided Surgery around the Head, VDI Fortschritt-Bericht 17: Biotechnik/Medizintechnik 258(17), (VDI-Verlag, Düsseldorf, 2005) 44.Google Scholar
- 7.M. Oehler, L. Pfaffmann and T. M. Buzug, Artefact Suppression in Computed Tomography using Iterative Reconstruction Methods, Biomedizinische Technik 50, 1130, 2005.Google Scholar
- 8.M. Oehler and T. M. Buzug, Gewichtete MLEM-Rekonstruktion zur Artefaktreduktion in der Transmissions-Computertomographie, Proceedings of 37th Annual Meeting DGMP, Regensburg (2006) 345.Google Scholar
- 9.M. Oehler and T. M. Buzug, Maximum-Likelihood-Ansatz zur Metallartefaktreduktion bei der Computertomographie, BVM 2006 (Springer, Berlin, 2006) 36.Google Scholar