Fig. 4

The mega-voltage fan-beam CT images of Catphan phantom before and after applying the in-house artifact correction. The corresponding projection data was acquired with 60 MU. The image thickness was 1 mm, 3 mm, and 3 mm for high-resolution, sensitometry, and uniformity modules, respectively. For high-resolution module, the display window was fixed at W/L: 800/100 HU. For the other two modules, the display window was at W/L: 400/40 HU. The solid arrows indicate the resolution test gauge at 6 line pairs per cm. The dashed arrows indicate the ring artifact. The dashed line indicates the location where the line profiles were extracted