title: Dosimetric analysis of upper gastrointestinal ulcer after carbon-ion radiotherapy for pancreatic cancer.
abstract: The aim of this study was to clarify the incidence, clinical risk factors, and dose-volume relationship of upper gastrointestinal (GI) ulcer after carbon-ion radiotherapy (C-ion RT) for pancreatic cancer.
  
  
  
  Fifty-eight pancreatic cancer patients were treated with C-ion RT from April 2014 to December 2015. The total dose was 55.2Gy (RBE) in 12 fractions. D2cm3 of GI tracts were restricted under 46Gy (RBE); RBE-weighted absorbed dose. The association between dosimetric parameters (V10-50, Dmax, D1cm3, D2cm3) and GI ulcer was examined using Spearman's correlation. The incidence of GI ulcer was compared between the two groups divided by the cutoff value.
  
  
  
  Twelve patients (21%) experienced gastric ulcer including only one (2%) grade 3 ulcer. There was no grade 4/5 toxicity or duodenal ulcer. V10-30 was significantly associated with gastric ulcer. The 1-year estimated risk of gastric ulcer for the determined cutoff values were 51% vs. 10% (V10, ⩾102cm(3) or less), 42% vs. 9% (V20, ⩾24cm(3) or less), 34% vs. 4% (V30, ⩾6cm(3) or less).
  
  
  
  The incidence of GI ulcer after C-ion RT was very low with the dose constraint of D2cm3 <46Gy (RBE). To further minimize the risk of GI ulcer, V10-30 should also be reduced.
authors.affiliation: Ion Beam Therapy Center, SAGA HIMAT Foundation, Tosu, Japan; Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. Electronic address: shinoto@saga-himat.jp.
authors.forename: Makoto
authors.initials: M
authors.lastname: Shinoto
authors.affiliation: Ion Beam Therapy Center, SAGA HIMAT Foundation, Tosu, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Shioyama
authors.affiliation: Ion Beam Therapy Center, SAGA HIMAT Foundation, Tosu, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Matsunobu
authors.affiliation: Ion Beam Therapy Center, SAGA HIMAT Foundation, Tosu, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Okamoto
authors.affiliation: Ion Beam Therapy Center, SAGA HIMAT Foundation, Tosu, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Suefuji
authors.affiliation: Ion Beam Therapy Center, SAGA HIMAT Foundation, Tosu, Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Toyama
authors.affiliation: Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Honda
authors.affiliation: Ion Beam Therapy Center, SAGA HIMAT Foundation, Tosu, Japan.
authors.forename: Sho
authors.initials: S
authors.lastname: Kudo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004381:Duodenal Ulcer / Q000209:etiology*; D005260:Female; D063193:Heavy Ion Radiotherapy / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000532:radiotherapy*; D012062:Relative Biological Effectiveness; D013276:Stomach Ulcer / Q000209:etiology*
keywords: Carbon-ion radiotherapy; Dose volume histogram; Gastrointestinal ulcer; Pancreatic cancer