Table 1.

Landmark-based measurements of matching deviation

		Matching
Error item		3 points-to-3 points	surface-to-surface
Distance (mm)	C1-M1	0.0 ± 0.0	1.4 ± 0.8
	C2-M2	0.3 ± 0.2	1.2 ± 0.6
	C3-M3	0.6 ± 0.3	1.9 ± 1.0
Angle (°)	Maximum interline angle	0.6 ± 0.6	1.3 ± 0.8
	Maximum interplane angle	0.0 ± 0.0	1.1 ± 0.8

Note) M1, M2, M3 and C1, C2, C3 are the centers of the reference ball landmarks registered to MRI-derived and CT-derived models, respectively. Distance between two corresponding landmarks registered to CT- and MRI-derived models averaged with standard deviation. Maximum interline angle is the largest value among the angular deviations between corresponding lines connecting corresponding two landmarks. The interplane angle is the angular deviation between the reference plane composed of three landmarks registered to the CT-derived model and that of the MRI-derived model.