Figure 3.

Difference of the deformation vector fields (display window: −20~20 voxels): (a): between ${\text{CT}}_{\text{deformed}}^{\text{demons}}(\to {\text{CBCT}}_{\text{original}})$ and ${\text{CT}}_{\text{deformed}}^{\text{demons}}(\to {\text{CBCT}}_{\text{no}\text{artifacts}})$; (b): between ${\text{CT}}_{\text{deformed}}^{\text{DISC}}(\to {\text{CBCT}}_{\text{original}})$ and ${\text{CT}}_{\text{deformed}}^{\text{demons}}(\to {\text{CBCT}}_{\text{no}\text{artifacts}})$.