title: Acceleration of MAP-EM algorithm via over-relaxation.
abstract: To improve the convergence rate of the effective maximum a posteriori expectation-maximization (MAP-EM) algorithm in tomographic reconstructions, this study proposes a modified MAP-EM which uses an over-relaxation factor to accelerate image reconstruction. The proposed method, called MAP-AEM, is evaluated and compared with the results for MAP-EM and for an ordered-subset algorithm, in terms of the convergence rate and noise properties. The results show that the proposed method converges numerically much faster than MAP-EM and with a speed that is comparable to that for an ordered-subset type method. The proposed method is effective in accelerating MAP-EM tomographic reconstruction.
authors.affiliation: Department of Medical Imaging and Radiological Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan. Electronic address: yj9611001@gmail.com.
authors.forename: Yu-Jung
authors.initials: YJ
authors.lastname: Tsai
authors.affiliation: Medical Physics Research Center, Institute of Radiological Research, Chang Gung University and Chang Gung Memorial Hospital, Taoyuan, Taiwan. Electronic address: b9003205@gmail.com.
authors.forename: Hsuan-Ming
authors.initials: HM
authors.lastname: Huang
authors.affiliation: Department of Electrical Engineering, Chang Gung University, Taoyuan, Taiwan. Electronic address: fang.phd@gmail.com.
authors.forename: Yu-Hua Dean
authors.initials: YH
authors.lastname: Fang
authors.affiliation: Department of Medical Imaging and Radiological Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan. Electronic address: billybilly319@gmail.com.
authors.forename: Shi-Ing
authors.initials: SI
authors.lastname: Chang
authors.affiliation: Department of Medical Imaging and Radiological Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan; Medical Physics Research Center, Institute of Radiological Research, Chang Gung University and Chang Gung Memorial Hospital, Taoyuan, Taiwan; Molecular Imaging Center and Department of Nuclear Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan. Electronic address: ihsiao@mail.cgu.edu.tw.
authors.forename: Ing-Tsung
authors.initials: IT
authors.lastname: Hsiao
mesh_terms: D000465:Algorithms; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D016247:Information Storage and Retrieval / Q000379:methods*; D016013:Likelihood Functions; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D014055:Tomography, Emission-Computed / Q000379:methods*
keywords: Faster tomographic reconstruction; MAP-EM algorithm; PET reconstruction; SPECT reconstruction