Figure 7.

The comparison of calculated NPS using four background estimation methods, for the 128‐pixel ((a), (b)) and the 32‐pixel ((c), (d)) ROIs, using FBP ((a), (c)) and iDose⁴ reconstruction with noise reduction level 3 ((b), (d)) algorithms. The ROI radius for the 128‐pixel and 32‐pixel ROIs are 0 and 30 mm, respectively. The ROIs were selected from the image acquired with the following parameters: 120 kVp, 250 effective mAs, and a sharp (C) reconstruction filter. The other scanning parameters are the same as that explained in the Materials & Methods section C.3.