Table 11.

Average and standard deviation (STD) offset between Vero lasers and central axis of the kV imaging system, evaluated monthly since installation $(\mathrm{n}=22)$, in the three principal directions

		Offset (mm)
Direction	Ave	Min	Max	STD
Lateral	$-0.210$	$-0.7$	0.4	0.279
Longitudinal	$-0.029$	$-0.7$	0.4	0.257
Vertical	0.314	0.0	0.7	0.213