Table 2.

Comparisons of patient positioning accuracy determined with respect to two different references (the SBL and the BB‐based) in terms of average displacements and the distribution of systematic errors in the three major directions

	Average displacement (mm) (n = 116)		1 SD for systematic error (mm) (n = 10)		Maximum displacements (mm)
Directions	Relative to BL	Relative to BB	Relative to BL	Relative to BB	Relative to BL	Relative to BB
left‐right	0.92	–1.41	1.95	3.47	6.8	15.0
anterior‐posterior	–0.27	–0.42	1.20	5.11	7.3	13.55
superior‐inferior	0.90	–0.83	2.12	3.15	9.9	11.3