Figure 4.

Frequency of target border LE greater than 2 mm in the LR, AP, and SI directions and in all three dimensions (3D) after individual registration of (a) the primary tumor and (b) involved lymph nodes. Nominal border alignment was defined as the transformation that minimized localization errors for opposing target borders in each cardinal direction. In several cases, this provided localization of all borders in a given direction to within 2 mm, corresponding to a frequency of zero. NMI: normalized mutual information.