Table 2. RMSE Values of Subtracted CT Volumes in Test 1.

Conversion Pairs (Input, Target Image)	Original (HU)	Converted (HU)	Differences (%)
From smooth to sharp kernel
B10f, B30f	16.31 ± 2.04	6.00 ± 0.91	−63.2 ± 2.9
B10f, B50f	58.53 ± 11.02	33.08 ± 8.71	−44.1 ± 5.2
B10f, B70f	119.48 ± 28.10	84.18 ± 25.54	−30.5 ± 5.4
B30f, B50f	44.57 ± 9.64	18.29 ± 4.34	−59.1 ± 1.8
B30f, B70f	107.47 ± 27.29	52.95 ± 15.35	−51.1 ± 2.0
B50f, B70f	66.03 ± 18.32	22.82 ± 6.63	−65.5 ± 1.9
From sharp to smooth kernel
B30f, B10f	16.31 ± 2.04	4.05 ± 0.36	−75.0 ± 1.7
B50f, B10f	58.53 ± 11.02	12.91 ± 2.65	−77.9 ± 1.8
B50f, B30f	44.57 ± 9.64	10.72 ± 2.37	−75.8 ± 2.1
B70f, B10f	119.48 ± 28.10	24.89 ± 6.55	−79.1 ± 2.4
B70f, B30f	107.47 ± 27.29	22.14 ± 5.98	−79.2 ± 2.6
B70f, B50f	66.03 ± 18.32	16.95 ± 5.03	−74.2 ± 2.4

Data are presented as mean ± SD (HU). Original: RMSE by subtracting between input and target images. Converted: RMSE by subtracting converted images from target images. Differences: 100 × (converted RMSE - original RMSE) / original RMSE. HU = Hounsfield unit, RMSE = root mean square error, SD = standard deviation