Figure 6.

Checkerboard comparisons of Case 2. Columns: transverse, coronal and sagittal images, respectively. (a): CT_original and CBCT_original; (b): ${\text{CT}}_{\text{deformed}}^{\text{demons}}$ and CBCT_original; (c): ${\text{CT}}_{\text{deformed}}^{\text{DISC}}$ and CBCT_original; (d): ${\text{CT}}_{\text{deformed}}^{\text{DISC}}$ and CBCT_corrected. The insets show the zoomed-in views, and the arrows indicate the regions contaminated by artifact or with geometrical distortion.