Table 4.

Mean and standard deviation (σ) of the position offset for the gantry, collimator, couch rotations for the MV machine, and kV gantry rotation using Winston‐Lutz test.

Isocenter Measurements $(\text{Mean}\pm \sigma )$
	Lat (mm)	Long (mm)	Vert (mm)
Gantry Radiation Isocenter	$0.27\pm 0.27$	$0.24\pm 0.24$	$0.34\pm 0.34$
Collimator Radiation Isocenter	$0.32\pm 0.21$	$0.24\pm 0.14$	n/a
Couch Radiation Isocenter	$0.32\pm 0.21$	$0.22\pm 0.13$	n/a
X‐ray	$0.15\pm 0.80$	$-0.40\pm 0.16$	$0.21\pm 0.09$
Infrared Isocenter	$0.02\pm 0.01$	$0.02\pm 0.01$	$0.02\pm 0.01$