Fig. 8.

First row: simulated CT images reconstructed with FBP (left) and iterative (right) algorithms. Second row: voxel-based noise magnitude maps in FBP and iterative images measured by 50 repetitive image acquisitions. Results suggest that the noise is locally stationary in FBP images but not stationary in the iterative images. Third row: noise reduction maps on the left and NPS curves, measured in the lungs, on the right, demonstrating that iterative images have less noise in uniform regions but higher noise in the edge voxels. The peak frequency of the NPS corresponding to lower noise (uniform regions) were lower in comparison with FBP images.