Table 3.

Average of center of mass positions measured over all phasesn=155. The mean position is slightly negative due to the longer duration of inhalation. The standard deviation of the mean position increases as the tumor motion increases and the inhale position has greater variability than the exhale position.

Radius (cm)	Motion (cm)	Mean position (cm)	Exhale		Inhale
			Mean position (cm)	Mean standard deviation (cm)	Mean position (cm)	Mean standard deviation (cm)
2	1	−0.027±0.066	0.28	0.084	−0.47	0.15
	2	−0.049±0.13	0.56	0.17	−0.94	0.3
	3	−0.064±0.19	0.86	0.24	−1.4	0.46
4	1	−0.020±0.059	0.29	0.078	−0.47	0.15
	2	−0.035±0.11	0.58	0.15	−0.93	0.29
	3	−0.047±0.17	0.87	0.23	−1.39	0.43