title: [18F]fluoromisonidazole and a new PET system with semiconductor detectors and a depth of interaction system for intensity modulated radiation therapy for nasopharyngeal cancer.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  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.
authors.affiliation: Department of Radiology, Hokkaido University Graduate School of Medicine, Hokkaido, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Yasuda
authors.forename: Rikiya
authors.initials: R
authors.lastname: Onimaru
authors.forename: Shozo
authors.initials: S
authors.lastname: Okamoto
authors.forename: Tohru
authors.initials: T
authors.lastname: Shiga
authors.forename: Norio
authors.initials: N
authors.lastname: Katoh
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Tsuchiya
authors.forename: Ryusuke
authors.initials: R
authors.lastname: Suzuki
authors.forename: Wataru
authors.initials: W
authors.lastname: Takeuchi
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kuge
authors.forename: Nagara
authors.initials: N
authors.lastname: Tamaki
authors.forename: Hiroki
authors.initials: H
authors.lastname: Shirato
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism; D016022:Case-Control Studies; D015687:Cell Hypoxia; D005260:Female; D006801:Humans; D007822:Laryngeal Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism; D008187:Lutetium; D008297:Male; D008875:Middle Aged; D008920:Misonidazole / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D009062:Mouth Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism; D064847:Multimodal Imaging / Q000379:methods; D009303:Nasopharyngeal Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000532:radiotherapy*; D009305:Nasopharynx / Q000000981:diagnostic imaging / Q000378:metabolism; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D061089:Radiotherapy, Image-Guided / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012666:Semiconductors / Q000295:instrumentation; D017640:Silicates; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D017640:Silicates; C477682:lutetium orthosilicate; C031843:fluoromisonidazole; D008187:Lutetium; D008920:Misonidazole