title: Analysis of equivalent uniform dose (EUD) and conventional radiation treatment parameters after primary and re-irradiation of malignant glioma.
abstract: BACKGROUND
  Re-irradiation is a reasonable second treatment option for patients with recurrent malignant glioma (MG) after previous radio(chemo)therapy. However, only limited data is available allowing for a precise selection of patients suitable for re-treatment in regard to safety and efficacy.
  
  
  METHODS
  Using the department database, 58 patients with two courses of percutaneous radiation were identified. Besides classical dose-volume histogram (DVH) parameters equivalent uniform dose (EUD) values were calculated for the tumor and organs at risk (OARs), retrospectively analyzed and correlated to survival outcome parameters. Cumulative EUD values were also calculated in all cases where previous OAR DVHs were available.
  
  
  RESULTS
  Median follow-up was 265 days and no relevant toxicity was observed after re-irradiation in our patient cohort during follow-up. Time interval between first and second irradiation was regularly above 6 months. As a conservative estimation of the cumulative EUD to the OARs, the EUDs of first and second irradiation were added. Median cumulative EUD to the optic chiasm was 48.8 Gy (range, 2.5-76.5 Gy), 57.4 Gy (range, 2.7-75.3 Gy) to the brainstem, 20.9/22.1 Gy (range, 0.0-68.3 Gy) to the right/left optic nerve and 73.8 Gy (range, 64.9-77.3 Gy) to the brain. No correlation between treated volume and survival was seen.
  
  
  CONCLUSIONS
  This study provides retrospective estimates on cumulative doses at the OARs. EUD values are derived and may serve as reference for further studies, including planning studies where specific constraints are needed.
authors: Department of Radiation Oncology, University of Munich, Marchioninistr, 15, Munich 81377, Germany. maximilian.niyazi@med.uni-muenchen.de.
authors: Maximilian
authors: M
authors: Niyazi
authors: Ivan
authors: I
authors: Karin
authors: Matthias
authors: M
authors: Söhn
authors: Silke B
authors: SB
authors: Nachbichler
authors: Peter
authors: P
authors: Lang
authors: Claus
authors: C
authors: Belka
authors: Ute
authors: U
authors: Ganswindt
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000465:Algorithms; D001932:Brain Neoplasms / Q000532:radiotherapy*; D059248:Chemoradiotherapy / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D005910:Glioma / Q000532:radiotherapy*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D058958:Organs at Risk; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D012189:Retrospective Studies; D016896:Treatment Outcome; D055815:Young Adult