Fig. 4

Graphs of voxel SUV differences between TRs and RR for individual voxels plotted against RR voxel SUV for 3 representative CT acquisition parameter combinations for low (CTDI 0.3 mGy) (a, b), medium (CTDI 1.0 mGy) (c, d) and high (CTDI 3.3 mGy) (e, f) X-ray exposure. CT reconstructed with filtered back projection (a, c, e) and iteratively (b, d, f). Each dot represents one voxel (black dots are voxels below QSD, and red dots are voxels greater than QSD). The green line is the linear regression fit for difference against reference value, and the blue line is the line of zero difference