Fig. 2
Representative images of the layers and volume of interest (VOIs). a Original mixed-energy images. b Layer-by-layer analysis for two peritumoral layers (outer layer 1 [yellow], outer layer 2 [green]) and two intratumoral layers (inner layer 1 [orange], inner layer 2 [blue]) with a 2-mm layer thickness. c VOI of the tumor. d VOIO1, tumor plus outer layer 1. e VOIO2, tumor plus outer layers 1 and 2. f VOII1, tumor minus inner layer 1. g VOII2, tumor minus inner layers 1 and 2. h The aforementioned analysis performed in the same manner with a 4-mm layer thickness