lutetium-orthosilicate and Mouth-Neoplasms

The impact of a new type of positron emission tomography (New PET) with semiconductor detectors using 18F-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.. 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 (NewPETGTVh and PET/CTGTVh, respectively). Dose escalation IMRT plans prescribing 84 Gy to each GTVh were carried out.. 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.. New PET was found to be useful for accurate dose escalation in FMISO-guided IMRT for patients with NPC.

Topics: Adult; Aged; Aged, 80 and over; Brain Neoplasms; Case-Control Studies; Cell Hypoxia; Female; Humans; Laryngeal Neoplasms; Lutetium; Male; Middle Aged; Misonidazole; Mouth Neoplasms; Multimodal Imaging; Nasopharyngeal Neoplasms; Nasopharynx; Positron-Emission Tomography; Radiopharmaceuticals; Radiotherapy Planning, Computer-Assisted; Radiotherapy, Image-Guided; Radiotherapy, Intensity-Modulated; Semiconductors; Silicates; Thyroid Neoplasms; Tomography, X-Ray Computed