摘要
Purpose: The impact of a new type of positron emission tomography (New PET) with semiconductor detectors using F-18-labeled fluoromisonidazole (FMISO)-guided intensity modulated radiation therapy (IMRT) was compared with a state-of-the-art PET/computed tomography (PET/CT) system in nasopharyngeal cancer (NPC) patients.
Methods and Materials: Twenty-four patients with non-NPC malignant tumors (control group) and 16 patients with NPC were subjected to FMISO-PET. The threshold of the tumor-to-muscle (T/M) ratio in each PET scan was calculated. The hypoxic volume within the gross tumor volume (GTVh) was determined using each PET ((NewPET)GTVh and (PET/CT)GTVh, respectively). Dose escalation IMRT plans prescribing 84 Gy to each GTVh were carried out.
Results: The threshold of the T/M ratio was 1.35 for New PET and 1.23 for PET/CT. The mean volume of NewPETGTVh was significantly smaller than that of PET/CTGTVh (1.5 +/- 1.6 cc vs 4.7 +/- 4.6 cc, respectively; P = .0020). The dose escalation IMRT plans using New PET were superior in dose distribution to those using PET/CT. Dose escalation was possible in all 10 New PET-guided plans but not in 1 PET/CT-guided plan, because the threshold dose to the brainstem was exceeded.
Conclusions: New PET was found to be useful for accurate dose escalation in FMISO-guided IMRT for patients with NPC. (c) 2013 Elsevier Inc.