Table 1.

Mean differences between two image guidance methods: 4DCT and ExacTrac respiratory‐triggered images.

Case#	Site	A/P (mm) a , b	S/I (mm)	L/R (mm)	Composite 3D (mm)
1	liver	$-1.1$	4.1	$-2.4$	5.9
2	liver	$-0.2$	4.0	$-0.4$	4.2
3	liver	$-2.4$	$-1.0$	3.2	4.7
4	liver	$-2.6$	1.9	1.7	3.6
5	liver	$-3.4$	3.2	0.8	4.9
6	lung	1.4	0.7	$-0.7$	2.5
$\text{Mean}\pm \text{Standard Deviation}$		$-1.4\pm 1.7$	$2.2\pm 2.0$	$0.4\pm 2.0$	$4.3\pm 1.2$

^a $\mathrm{A}/\mathrm{P}=\hspace{0.17em}\text{anterior}/\text{posterior}$; $\mathrm{S}/\mathrm{I}=\hspace{0.17em}\text{inferior}/\text{superior}$; $\mathrm{L}/\mathrm{R}=\hspace{0.17em}\text{left}/\text{right}$.

^bThe directions of ExacTrac image guidance shifts relative to 4DCT shifts were: $+\text{posterior}$; $+\text{superior}$; $+\text{right}$.