Table 2. Filter settings.
| Unfiltered | Isotropic Gaussian filter | Anisotropic bilateral filter | ||||
|---|---|---|---|---|---|---|
| Thickness (mm) | SDin (HU) | σd (mm) | SDout (HU) | σd (mm) | σr (HU2) | SDout (HU) |
| 0.8 | 14.9 (2.95) | 2.5 | 0.76 (0.16) | 3.0 | 50.0 | 0.74 (0.16) |
| 2.4 | 11.1 (1.94) | 2.5 | 0.75 (0.15) | 3.0 | 37.3 | 0.75 (0.17) |
| 4.8 | 8.4 (1.37) | 2.5 | 0.77 (0.15) | 3.0 | 28.1 | 0.76 (0.18) |
| 9.6 | 6.1 (0.99) | 2.5 | 0.70 (0.15) | 3.0 | 20.5 | 0.74 (0.18) |
The standard deviations σ d and σ r of the filter kernels, and the median noise levels of the unfiltered and filtered data, SD in and SD out, at each slice thickness. The number between brackets is the inter-quartile range (IQR).