Figure 2

Left panel: Coronal reconstruction of the end-expiration phase bin of patient 13, showing both PTV_4DCT1(violet contour) and PTV_4DCT2 (pink contour). Colorwash displays of the 80%, 60% and 20% isodoses show the most caudal area of PTV_4DCT1 to lie in the 20% isodose area. Right panel: A corresponding color intensity projection in the same patient with the color bar providing time-related positional information (white = 100% presence; blue = 90%; green = 50%; orange = 10%). This indicates that the most caudal PTV region represents a site occupied by the tumor for 10–20% of the respiratory cycle.