Table 2.

Population geometric uncertainties (in mm) at planning and during 6-fraction SBRT evaluated with deformable image registration.

		Exhale CT to Inhale CT		Exhale CT to Exhale CBCT		Exhale CBCT to Inhale CBCT
		Rigid	Deformation	Rigid	Deformation	Rigid	Deformation
		Mean, SD	SD*, RMS†	Mean, ΣCOM, σCOM	ΣDEF, σDEF	Mean, ΣCOM, σCOM	ΣDEF, σDEF
GTV	LR	−1.3, 2.1	1.0, 1.0	0.7, 1.8, 1.7	1.0, 1.2	−1.2, 1.1, 1.1	0.5, 0.4
	AP	3.7, 3.0	1.7, 0.8	−0.8, 2.2, 1.9	0.9, 1.1	2.9, 1.6, 1.5	0.6, 0.5
	SI	8.8, 5.0	1.9, 1.2	−0.5, 2.6, 2.4	1.0, 1.2	7.0, 3.1, 1.6	0.7, 0.8
Liver	LR	−1.1, 2.0	0.5, 1.5	0.5, 1.7, 1.9	0.4, 1.6	−1.2, 1.0, 1.0	0.2, 0.7
	AP	3.9, 2.3	0.4, 1.8	−0.8, 2.2, 1.9	0.4, 1.6	3.1, 1.7, 1.5	0.2, 1.0
	SI	9.0, 5.2	0.5, 2.0	−0.4, 2.1, 2.4	0.3, 1.8	7.1, 3.2, 1.4	0.2, 1.2

Abbreviations: CT=computed tomography; CBCT=cone-beam CT; COM=centre-of-mass; DEF=deformation; SD=standard deviation; RMS=root mean square; Σ=group systematic error; σ=group random error; GTV=gross tumor volumes;

Notes: Positive M values are displacements in the left, anterior, inferior directions.

^*SD of each patient’s mean elements’ motion (minus liver COM).

^†RMS of the SD of the each patient’s elements’ motion (minus liver COM).