Figure 1.

Figure shows the two types of images, an image pair of full lung volumetric phases EE and EI from a 4DCT scan and a Xe-CT scan acquired at the end of expiration over 45 respiratory cycles (EE₀ to EE₄₄), which are analyzed during the processing. Transformation T1 registers EI to EE data and can be used to assess local lung function via calculations of three ventilation measures: SAJ, SACJ, and SAI. The 45 distinctive partial lung volumetric Xe-CT scans EE₀ to EE₄₄ are used to calculate Xe-CT based measure of sV. Transformation T2 maps the sV data into the coordinate system of the EE image (end expiration phase of the 4DCT scan) to allow direct comparison with the 4DCT and registration based measures of ventilation. Both EE and EE₀ are at volumes near end inspiration. (Shaded boxes indicate CT image data; white boxes indicated derived or calculated data; thick arrows indicate image registration transformations being calculated; thin solid lines indicate other operations.)