title: Weighted expectation maximization reconstruction algorithms with application to gated megavoltage tomography.
abstract: We propose and investigate weighted expectation maximization (EM) algorithms for image reconstruction in x-ray tomography. The development of the algorithms is motivated by the respiratory-gated megavoltage tomography problem, in which the acquired asymmetric cone-beam projections are limited in number and unevenly sampled over view angle. In these cases, images reconstructed by use of the conventional EM algorithm can contain ring- and streak-like artefacts that are attributable to a combination of data inconsistencies and truncation of the projection data. By use of computer-simulated and clinical gated fan-beam megavoltage projection data, we demonstrate that the proposed weighted EM algorithms effectively mitigate such image artefacts.
authors.affiliation: Department of Biomedical Engineering, Illinois Institute of Technology, 10 West 32nd Street, E1-116, Chicago, IL 60616, USA.
authors.forename: Jin
authors.initials: J
authors.lastname: Zhang
authors.forename: Daxin
authors.initials: D
authors.lastname: Shi
authors.forename: Mark A
authors.initials: MA
authors.lastname: Anastasio
authors.forename: Jussi
authors.initials: J
authors.lastname: Sillanpaa
authors.forename: Jenghwa
authors.initials: J
authors.lastname: Chang
mesh_terms: D000465:Algorithms; D016477:Artifacts; D003198:Computer Simulation; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D015233:Models, Statistical; D010363:Pattern Recognition, Automated; D019047:Phantoms, Imaging; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D012984:Software; D014056:Tomography, X-Ray / Q000379:methods*