TABLE 2.

Registration errors (mean ± STD) with different shifts of couch in the x, y, and z axes for reposition accuracy

	Registration error values (mm)
Registration methods		2 mm	3 mm	5 mm	10 mm	Total
x (Lat.)	ICP	0.67 $\pm$ 0.05	1.11 $\pm$ 0.13	1.36 $\pm$ 0.05	3.51 $\pm$ 0.05	1.66 $\pm$ 1.15
	NDT	0.65 $\pm$ 0.06	1.10 $\pm$ 0.09	1.34 $\pm$ 0.13	1.35 $\pm$ 0.62	1.20 $\pm$ 0.97
y (Long.)	ICP	0.28 $\pm$ 0.08	0.32 $\pm$ 0.12	1.85 $\pm$ 0.07	2.35 $\pm$ 0.30	1.39 $\pm$ 0.83
	NDT	0.10 $\pm$ 0.01	0.16 $\pm$ 0.13	0.64 $\pm$ 0.27	2.16 $\pm$ 0.10	1.11 $\pm$ 0.45
z (Vert.)	ICP	0.45 $\pm$ 0.08	0.97 $\pm$ 0.14	1.55 $\pm$ 0.12	$2.58\pm$ 0.08	0.76 $\pm$ 0.88
	NDT	0.30 $\pm$ 0.13	0.96 $\pm$ 0.12	1.24 $\pm$ 0.06	1.04 $\pm$ 0.16	0.88 $\pm$ 0.39

Experiments were repeated three times per algorithm.