Table 1. Comparison of GTV volumes defined by each observer with dual-modality image fusion (MRI/CT) and tri-modality (MRI/CT/PET) image fusion.

Patient	GTVMRI/CT (cm3)					GTVMRI/CT/PET (cm3)
	Obs. 1	Obs. 2	Obs. 3	Mean	COV	Obs. 1	Obs. 2	Obs. 3	Mean	COV
1	19.91	22.72	20.47	21.03	0.07	17.91	19.82	17.69	18.47	0.06
2	14.39	17.01	13.94	15.11	0.11	12.61	14.09	13.27	13.32	0.06
3	2.96	2.92	1.82	2.57	0.25	1.89	1.92	1.64	1.82	0.08

GTV = gross tumor volume; Obs. 1 = observer 1; COV = coefficient of variation.