Fig. 2

“Bland-Altman plots of primary tumor volumes comparing reference segmentation, ellipsoid approximation and radiotherapy segmentation”. Comparison of volume approximation in diagnostic CT scans with ellipsoid formula with manual slice-by-slice segmentation in diagnostic CT scans as reference (a). Inter rater variability (b) and intra rater variability (c) of the ellipsoid formula and comparison of segmentations in diagnostic CT scans with radiotherapy-planning CT scans (d). In all figures, the x–axis represents the mean of the two methods in milliliters (ml) on a logarithmic scale. The y–axis represents percent difference of the tested method compared to the reference method. The horizontal dotted line shows the zero percentage difference level on the y-axis. The horizontal bald line shows the mean bias indicating the average under- or overestimation of the test-method. The lower and upper horizontal lines represent the limits of agreement (average percent difference ± 1.96 standard deviations)