Figure 5.

Mean absolute centroid LE in the LR, AP, and SI directions and in three-dimensional magnitude (3D) after simultaneous “Averaged” registration of both the primary tumor and involved lymph nodes. This registration technique involved separate alignments of each individual target volume, which were then averaged together to obtain the final transform. Nominal centroid alignment was defined as the registration that minimized centroid LE for all targets simultaneously using only translational degrees of freedom, indicating the degree of intertarget variability throughout treatment. Asterisks denote significantly improved target localization relative to the initial bony-anatomy alignment. NMI: normalized mutual information.