title: Proton therapy radiation pneumonitis local dose-response in esophagus cancer patients.
abstract: OBJECTIVE
  This study quantifies pulmonary radiation toxicity in patients who received proton therapy for esophagus cancer.
  
  
  METHODS
  We retrospectively studied 100 esophagus cancer patients treated with proton therapy. The linearity of the enhanced FDG uptake vs. proton dose was evaluated using the Akaike Information Criterion (AIC). Pneumonitis symptoms (RP) were assessed using the Common Toxicity Criteria for Adverse Events version 4.0 (CTCAEv4). The interaction of the imaging response with dosimetric parameters and symptoms was evaluated.
  
  
  RESULTS
  The RP scores were: 0 grade 4/5, 7 grade 3, 20 grade 2, 37 grade 1, and 36 grade 0. Each dosimetric parameter was significantly higher for the symptomatic group. The AIC winning models were 30 linear, 52 linear quadratic, and 18 linear logarithmic. There was no significant difference in the linear coefficient between models. The slope of the FDG vs. proton dose response was 0.022 for the symptomatic and 0.012 for the asymptomatic (p=0.014). Combining dosimetric parameters with the slope did not improve the sensitivity or accuracy in identifying symptomatic cases.
  
  
  CONCLUSIONS
  The proton radiation dose response on FDG PET/CT imaging exhibited a predominantly linear dose response on modeling. Symptomatic patients had a higher dose response slope.
authors.affiliation: The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Alfredo E
authors.initials: AE
authors.lastname: Echeverria
authors.forename: Matthew
authors.initials: M
authors.lastname: McCurdy
authors.forename: Richard
authors.initials: R
authors.lastname: Castillo
authors.forename: Vincent
authors.initials: V
authors.lastname: Bernard
authors.forename: Natalia Velez
authors.initials: NV
authors.lastname: Ramos
authors.forename: William
authors.initials: W
authors.lastname: Buckley
authors.forename: Edward
authors.initials: E
authors.lastname: Castillo
authors.forename: Ping
authors.initials: P
authors.lastname: Liu
authors.forename: Josue
authors.initials: J
authors.lastname: Martinez
authors.forename: Thomas
authors.initials: T
authors.lastname: Guerrero
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004307:Dose-Response Relationship, Radiation; D004938:Esophageal Neoplasms / Q000532:radiotherapy*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D061766:Proton Therapy; D011522:Protons / Q000009:adverse effects*; D017564:Radiation Pneumonitis / Q000209:etiology*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
chemical_list: D011522:Protons; D019788:Fluorodeoxyglucose F18