Table 1. Summary of patients information.

	Patient	1	2	3	4	5	6	7	8
Tumor location	Geometric	I-A-L	S-A-R	S-P-R	S-P-L	I-P-R	S-A-L	S-P-L	I-P-L
Breathing cycle [s]	Mean	2.8	3.5	3.0	4.1	5.8	4.0	5.3	3.3
Tumor displacement [mm]	LR	1.2	0.9	3.6	2.5	2.5	1.3	0.4	0.8
	AP	1.3	0.6	3.4	0.5	3.3	1.8	2.3	2.9
	SI	5.1	7.8	10.2	6.3	12.6	3.7	8.2	7.9
	3D	5.4	7.9	11.2	6.7	13.3	4.0	8.5	8.3
Distance GTV COM to [mm]	Marker 1	20.6	19.0	30.8	43.5	33.8	49.0	25.0	30.8
	Marker 2	29.5	24.0	41.1	41.5	28.3	33.1	21.1	25.7
	Marker 3	17.9	41.6	18.0	44.6	54.9	31.5	36.9	40.8
	Marker COM	22.3	40.3	26.6	32.2	26.1	18.1	38.7	29.9
Distance between markers [mm]	Marker 1—2	12.0	15.9	14.1	30.4	25.3	19.6	23.3	21.3
	Marker 2—3	16.6	29.5	21.6	35.7	20.1	15.2	17.3	31.7
	Marker 3—1	29.2	58.9	31.8	14.2	41.9	40.8	19	43.7
GTV [cm3]	Mid-ventilation	7.6	29.0	29.3	11.6	2.4	4.0	4.5	64.8
	Mean	7.4	29.7	28.8	11.4	2.5	4.2	4.4	65.4
	CV [%]	0.5	1.2	1.7	2.4	0.1	0.4	0.9	1.0
Liver volume [cm3]	Mid-ventilation	1904	2324	1343	1458	912	2156	1744	1596
	Mean	1908	2321	1343	1458	903	2172	1722	1594
	CV [%]	7.6	1.4	3.7	5.1	12.5	10.1	10.7	3.5

Table notes: Tumor location is the geometric octant of where the tumor is with regards to the liver COM. The abbreviations used correspond to Superior-Inferior, Anterior-Posterior and Left-Right. Breathing cycle time was determined from the external respiratory signal, acquired during the 4DCT scan. Tumor displacements are computed using the markers COM as surrogate of the tumor. Distance of GTV COM to fiducial markers and between markers are measured in the mid-ventilation phase. GTV and liver volumes are estimated for every phase based on DIR. COM = center of mass, CV = coefficient of variation.