title: Use of gEUD for predicting ear and pituitary gland damage following proton and photon radiation therapy.
abstract: OBJECTIVE
  To determine the relationship between the dose to the inner ear or pituitary gland and radiation-induced late effects of skull base radiation therapy.
  
  
  METHODS
  140 patients treated between 2000 and 2008 were considered for this study. Hearing loss and endocrine dysfunction were retrospectively reviewed on pre- and post-radiation therapy audiometry or endocrine assessments. Two normal tissue complication probability (NTCP) models were considered (Lyman-Kutcher-Burman and log-logistic) whose parameters were fitted to patient data using receiver operating characteristics and maximum likelihood analysis. The method provided an estimation of the parameters of a generalized equivalent uniform dose (gEUD)-based NTCP after conversion of dose-volume histograms to equivalent doses.
  
  
  RESULTS
  All 140 patients had a minimum follow up of 26 months. 26% and 44% of patients experienced mild hearing loss and endocrine dysfunction, respectively. The fitted values for TD50 and γ50 ranged from 53.6 to 60.7 Gy and from 1.9 to 2.9 for the inner ear and were equal to 60.6 Gy and 4.9 for the pituitary gland, respectively. All models were ranked equal according to Akaike's information criterion.
  
  
  CONCLUSIONS
  Mean dose and gEUD may be used as predictive factors for late ear and pituitary gland late complications after skull base proton and photon radiation therapy.
  
  
  CONCLUSIONS
  In this study, we have reported mean dose effects and dose-response relationship of small organs at risk (partial volumes of the inner ear and pituitary gland), which could be useful to define optimal dose constraints resulting in an improved therapeutic ratio.
authors: 1 Department of Radiotherapy, Institut Curie, Orsay Proton Therapy Centre, Paris, France.
authors: L
authors: L
authors: De Marzi
authors: L
authors: L
authors: Feuvret
authors: T
authors: T
authors: Boulé
authors: J-L
authors: JL
authors: Habrand
authors: F
authors: F
authors: Martin
authors: V
authors: V
authors: Calugaru
authors: N
authors: N
authors: Fournier-Bidoz
authors: R
authors: R
authors: Ferrand
authors: A
authors: A
authors: Mazal
mesh_terms: D000328:Adult; D001299:Audiometry; D002648:Child; D004307:Dose-Response Relationship, Radiation; D005260:Female; D034381:Hearing Loss / Q000175:diagnosis*; D006801:Humans; D007031:Hypothalamus / Q000528:radiation effects; D008297:Male; D058958:Organs at Risk; D017785:Photons; D010902:Pituitary Gland / Q000528:radiation effects*; D011237:Predictive Value of Tests; D011522:Protons; D011829:Radiation Dosage; D011832:Radiation Injuries / Q000175:diagnosis*; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal; D012189:Retrospective Studies; D019292:Skull Base Neoplasms / Q000532:radiotherapy*
chemical_list: D011522:Protons