RC% across reconstruction algorithm (FBP, AIDR, FIRST) and CTDIvol (0.3 to 4.1 mGy) for the 10 mm in diameter nodules of −800 (A), −630 (B) and −10 HU (C) density. Values were calculated from pooled volume estimates of all objects in the main subset, replicates, and kVp settings. FBP, filtered back projection; AIDR, adaptive iterative dose reduction; FIRST, Forward projected model-based Iterative Reconstruction SoluTion; HU, Hounsfield units; CTDI, computed tomography scan dose index; RC, repeatability coefficient.