Fig. 4.

Standard dose contrast enhanced-chest CT in 77-year-old man (BMI, 22 kg/m²) with esophageal cancer.

Transverse CT image at 5 mm thickness with full radiation dose reconstructed with (A) FBP and (B) IRIS, and (C) with half radiation dose reconstructed with IRIS. When two readers compared F-FBP (A) and F-IRIS (B) images, as reconstruction effect, readers' preference scores were 2 and 2 each for mediastinum, 4 and 3 for lung 5 mm images, 4 and 3 for lung 1 mm images and 4 and 3 for overall (not shown). When they compared F-FBP (A) and H-IRIS (C) as reconstruction effect and radiation dose effect, readers had preference scores of 2 and 2 each for mediastinum, 4 and 4 for lung 5 mm/1 mm images, and 3 overall (not shown). BMI = body mass index, F-FBP = full dose image with filtered back projection, F-IRIS = full dose image with iterative reconstruction in image space, H-IRIS = half dose image with iterative reconstruction in image space