Table 3.

Errors of bony structures and metal markers at patient positioning

	Setup error of bony structure			Marker error
	L(+) R(−)	S(+) I(−)	A(+) P(−)	L(+) R(−)	S(+) I(−)	A(+) P(−)
Number of points	309	546	319	82	151	69
Average	0.0	0.0	0.0	−0.1	−0.8	0.0
SD (σ) (mm)	0.5	0.5	0.5	2.4	3.5	2.6
Minimum (mm)	−1.9	−1.8	−1.9	−12.2	−11.2	−13.0
Maximum (mm)	1.9	2.1	2.1	3.9	8.1	5.8
SD fitted by L.S. (mm)				1.4	1.7	1.8

Data of superior–inferior (SI) direction are estimated using frontal and lateral images. The absolute values of the minimums indicate the maximum values of negative directions. The error values are those corresponding to the iso-center plane. The values in the bottom row indicate SDs of least-square (LS) fit of the marker error distribution (Fig. 6b) to a normal distribution (see text)