Fig. 3.
Effect of gradient scaling in regularized OS-SQS algorithm with GE performance phantom (GEPP) in helical CT: Each image is reconstructed after running 20 iterations of OS algorithm with 328 subsets, using ordinary and proposed scaling approaches. Standard deviation σ of a uniform region (in white box) is computed for comparison. We compute full-width half maximum (FWHM) of a tungsten wire (red arrow) to measure the resolution. (The result of a convergent algorithm is shown for reference. Images are cropped for better visualization.)