Study Number of patients CT/MRI/PET/PET-CT radiotherapy target volumes
Ciernik et al. [21] 39 (12 patients with head and neck cancer) > 25% GTV increase with PET-CT vs CT
> 25% GTV decrease with PET-CT vs CT
Heron et al. [23] 21 Mean GTV 42.7 cm3 with PET vs 65 cm3 with CT
Scarfone et al. [24] 6 Mean GTV primary tumor 22.2 cm3 with CT vs 19.9 cm3 with PET
Paulino et al. [27] 40 Median GTV 20.3 cm3 with PET vs 37.2 cm3 with CT
Newbold et al. [32] 18 (9 unknown primary tumors) Median  6.1 cm3 increase in GTV (combined primary and nodal) with PET-CT vs CT for known primary tumors
Median 10.1 cm3 increase in CTV with PET-CT for known primary site
Median 6.3 cm3 increase in GTV with PET-CT vs CT for unknown primary tumors
Median 155.4 cm3 increase in CTV with PET-CT vs CT for unknown primary tumors
Guido et al. [33] 38 Mean GTV for CT 34.54 cm3 vs 29.38 cm3 for PET-CT
Breen et al. [34] 10 Mean GTV primary tumor 26.9 cm3 with CT vs 27.7 cm3 with CE-CT vs 26.5 cm3 with PET/CT
Wang et al. [35] 28 Mean GTV 68.8 cm3 with CT vs 61.8 cm3 with PET-CT
Deantonio et al. [34] 22 Mean GTV with PET/CT 26.0 cm3 (composite volume between PET and CT)
Mean GTV 5.5 cm3 with PET
Mean GTV 8.1 cm3 with CT
Mean GTV 11.2 cm3 with CT&PET (the common volume of the two imaging modalities)
El-Bassiouni et al. [38] 25 Median GTV for CT 29.6 cm3, mean GTV for CT 41.6 cm3
Median GTV for PET 23.0 cm3, mean GTV for PET 34.2 cm3
Median PTV for CT 171.5 cm3, mean PTV for CT 204.1 cm3
Median PTV for PET 127.7 cm3, mean PTV for PET 165.9 cm3
Daisne et al. [39] 29 (9 with total laryngectomy) Oropharyngeal tumors:
Mean GTV 32.0 cm3 with CT
Mean GTV 27.9 cm3 with MRI
Mean GTV 20.3 cm3 with PET
Laryngeal and hypopharyngeal tumors:
Mean GTV 21.4 cm3 with CT
Mean GTV 21.4 cm3 with MRI
Mean GTV 16.4 cm3 with PET
Mean surgical GTV 12.6 cm3
FDG-PET, [18F]Fluoro-Deoxy-Glucose-Positron Emission Tomography, CT, Computed Tomography, MRI, Magnetic Resonance Imaging, PET-CT, Positron Emission Tomography-Computed Tomography, CE-CT, Contrast Enhanced Computed Tomography, GTV, gross tumor volume, CTV, Clinical Target Volume, PTV, Planning Target Volume
Table 1: FDG-PET for radiotherapy target volumes delineation for head and neck cancer.