Aims: To evaluate the value of PET/CT in diagnostic and staging of NPC. To study the value of PET/CT simualation in radiotherapy planning for NPC. Subjects: 110 pts newly diagnosed with NPC (histophathology confirm) have been performed PET/CT for staging and simulation and then being treated with linear accelerator. At the Nuclear Medidne and Oncology Centre, Bach Mai hospital, Hanoi, from 10/2009-10/2013. Methods: description, prospective. Result: 1. Among 110 pts: male/female is 2,9: 1, average age 52,1 + or - 14,9. Group 40-60 years old accounted for highest (41 percent). SUV of tumor is 10,88 + or - 4,70 (2,51-24,96)
lymph node is 7,48 + or - 4,79 (2,56-26,22). Changing stage in 30,8 percent pts. 2. Changing GTV-PET (threshold is changing 25 percent volume) in 74/96 pts (77,1 percent): increase in 21,8 percent pts and decrease in 55,2 percent pts. Average GTV-PET volume is smaller than GTV-CT: 94,3 + or -13,2 cm3 vs 125,2 + or - 17,9 cm3. Conclusions: PET/CT scan helps diagnostic stage of diseases accurately, then giving the most appropriate treatment. PET/CT simulation for radiation therapy planning has some significant advantages: define accurate radiation volume, high dose focus in tumor while separate the normal surrounding tissue, limit the side effects of treatment and improve outcomes.