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. Author manuscript; available in PMC: 2015 Apr 7.
Published in final edited form as: Phys Med Biol. 2014 Mar 14;59(7):1801–1814. doi: 10.1088/0031-9155/59/7/1801

FIG. 2.

FIG. 2

Reconstructed images and plots of the objective function and stopping metric values for GPBB and UPN on the digital Shepp-Logan phantom. A total of 66 projections are used in the study. Row (1): using a simulated noise level of I0=5×105 photons per ray; (2): using I0=5×104. Column (a) reconstructed CT image using ABOCS with the UPN implementation, display window: [−500 500] HU; (b) difference image compared with the ground truth, display window: [−100 100] HU; (c) 1d plot of the objective function values versus the iteration number; (d) 1d plot of the stopping metric versus the iteration number.