Volume | Sum of voxels | -
Spatial resolution
-
Inspiration level
| Mass | Volume X CT density |
Total lung | Both lungs or right/left | Tissue volume | Mass/tissue density |
Lobar | Sum of voxels on specific lobes | Air volume | Total volume – tissue volume |
X-ray attenuation (measured in HU) | | -
Image noise
-
Inspiration level
| CT density (g·mL−1) | (HU + 1000)/1000 |
| | Specific lung inflation | (1/CT density) – (1/tissue density) |
Low attenuation area | % voxels < pre-defined threshold (i.e. -950 HU) | -
Image noise
-
Inspiration level
| Low attenuation Cluster analysis | Slope of regression line of cumulative number of low attenuation clusters versus size of low attenuation cluster |
Percentile | HU at pre-defined percentile value of frequency distribution of X-ray attenutation values (i.e. lowest 15th percentile) | -
Image noise
-
Inspiration level
| | |