title: Dose distribution resulting from changes in aeration of nasal cavity or paranasal sinus cancer in the proton therapy.
abstract: OBJECTIVE
  Aeration in the nasal cavity and paranasal sinus (NCPS) was investigated during the course of proton therapy (PT), and the influence of aeration on the dose distribution was determined.
  
  
  METHODS
  Twenty patients with NCPS cancer (10 nasal cavity, 10 paranasal sinus) were analyzed. All the patients received a total proton beam irradiation dose of 38-78.4 Gray equivalents (GyE). Two to five CT examinations were performed during the course of treatment. The aeration ratio inside the cavity/sinus was calculated for each CT observation. Moreover, a simulation study supposing that the first treatment plan had been continued until the end of treatment was performed using the subsequent CT findings.
  
  
  RESULTS
  The aeration ratio was increased in 18 patients. The largest increase was from 15% to 82%. Three patients had a simulated maximum cumulative dose in the brainstem of beyond 60 GyE, while 10 patients had a simulated maximum cumulative dose in the optic chiasm of beyond 50 GyE. The shortest simulated time period to reach the dose limitation was 21 days.
  
  
  CONCLUSIONS
  Aeration in the NCPS is altered during the course of PT treatment and can greatly alter the dose distribution in the brainstem and optic chiasm.
authors.affiliation: Proton Medical Research Center, University of Tsukuba, Japan. Electronic address: fukumitsun@yahoo.co.jp.
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Fukumitsu
authors.affiliation: Proton Medical Research Center, University of Tsukuba, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Ishikawa
authors.affiliation: Proton Medical Research Center, University of Tsukuba, Japan.
authors.forename: Kayoko
authors.initials: K
authors.lastname: Ohnishi
authors.affiliation: Proton Medical Research Center, University of Tsukuba, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Terunuma
authors.affiliation: Proton Medical Research Center, University of Tsukuba, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Mizumoto
authors.affiliation: Proton Medical Research Center, University of Tsukuba, Japan.
authors.forename: Haruko
authors.initials: H
authors.lastname: Numajiri
authors.affiliation: Proton Medical Research Center, University of Tsukuba, Japan.
authors.forename: Teruhito
authors.initials: T
authors.lastname: Aihara
authors.affiliation: Proton Medical Research Center, University of Tsukuba, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Okumura
authors.affiliation: Proton Medical Research Center, University of Tsukuba, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Tsuboi
authors.affiliation: Proton Medical Research Center, University of Tsukuba, Japan.
authors.forename: Takeji
authors.initials: T
authors.lastname: Sakae
authors.affiliation: Proton Medical Research Center, University of Tsukuba, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Sakurai
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000388:Air; D001933:Brain Stem / Q000528:radiation effects; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009296:Nasal Cavity; D009669:Nose Neoplasms / Q000532:radiotherapy*; D009897:Optic Chiasm / Q000528:radiation effects; D010255:Paranasal Sinus Neoplasms / Q000532:radiotherapy; D061766:Proton Therapy / Q000379:methods*; D011879:Radiotherapy Dosage; D012160:Retina / Q000528:radiation effects; D012189:Retrospective Studies
keywords: Aeration; Cancer; Nasal cavity; Paranasal sinus; Proton beam therapy