Table 2. Calculated systematic and random errors in 3D translation and rotation using three registration methods.

Registration methods	3D translation				3D rotation
	LR (mm)	AP (mm)	SI (mm)		Roll (°)	Pitch (°)	Yaw (°)
Fiducial registration
Group mean error M	−0.08	0.11	0.21		−0.01	0.00	−0.01
Systematic error Σ	0.57	0.22	0.26		0.15	0.00	0.17
Random error σ	2.07	0.54	1.32		0.50	0.02	0.88
Anatomical registration
Group mean error M	−0.03	−0.08	0.03		0.00	0.00	0.13
Systematic error Σ	0.28	0.10	0.52		0.17	0.00	0.33
Random error σ	1.34	0.73	2.04		0.67	0.02	1.10
Gross registration
Group mean error M	−0.10	0.03	0.25		0.00	0.00	0.13
Systematic error Σ	0.53	0.22	0.49		0.10	0.00	0.27
Random error σ	2.24	0.86	2.61		0.44	0.02	0.95