Figure 2.

Checkerboard comparisons of the DIR results based on the simulation dataset. Columns: transverse, coronal and sagittal images, respectively. (a): CT_original and CBCT_original; (b): ${\text{CT}}_{\text{deformed}}^{\text{demons}}(\to {\text{CBCT}}_{\text{original}})$ and CBCT_original; (c): ${\text{CT}}_{\text{deformed}}^{\text{DISC}}(\to {\text{CBCT}}_{\text{original}})$ and CBCT_original; (d): ${\text{CT}}_{\text{deformed}}^{\text{DISC}}(\to {\text{CBCT}}_{\text{original}})$ and CBCT_corrected. The insets show the zoomed-in views.