Application of computed tomography and magnetic resonance imaging fusion images for delineating gross tumor volume in three-dimensional conformal radiotherapy of nasopharyngeal carcinoma

To evaluate computed tomography (CT) and magnec resonance imaging (MRI) fusion images for delineang gross tumor volume (GTV) in three-dimensional conformal radiotherapy (3D-CRT) of nasophanrygeal carcinoma (NPC), and compare treatment outcomes between CT- and CTㄒbased targets.
A total of 120 NPC paents treated with 3D-CRT were included, in which, 60 each were treated with CT-based and 60 with CTㄒ fusion targets. We explored the clinical applicaon of CTㄒ fusion targets and compared the 1-, 3-, and 5-year survival and relapse rates between both targets.
The clinical characteriscs and treatment factors were well balanced. The differences in public volume using CT alone in the CTㄒ (Group A) and the CT arm (Group B) were not significant (33.6±2.18 vs. 34.3±2.98, P > 0.05). The public volumes of GTV in the two arms were 49.48±2.46 cm3 and 33.6±2.18 cm3 respecvely (P The variability in GTV delineaon in NPC was ascribed to intermodality and not interobserver variability. CT fusion images likely reduced the 3-year out-of-field relapse rate.