Figure 7From: Determination of regional lung air volume distribution at mid-tidal breathing from computed tomography: a retrospective study of normal variability and reproducibility This illustrates the results of shell analysis of lung air volume. The graphs show the variation of (a) the percentage of total lung air volume and (b) fractional air volume concentration from the centre of the lung (shell 1) to the periphery (shell 10). Data for the right (♦) and left (■) lungs are shown separately.Back to article page