title: ESTRO-ACROP guideline "target delineation of glioblastomas".
abstract: OBJECTIVE
  Target delineation in glioblastoma (GBM) varies substantially between different institutions and several consensus statements are available. This guideline aims to develop a joint European consensus on the delineation of the clinical target volume in patients with a glioblastoma (GBM).
  
  
  METHODS
  A literature search was conducted in PubMed that evaluated adults with GBM. Both MeSH terms and text words were used and the following search strategy was applied: ("Glioblastoma/radiotherapy" [MeSH] OR "glioblastoma" OR "malignant glioma" OR high-grade glioma) AND ((delineation) OR (target volume) OR (CTV) OR (PTV) OR (margin) OR (recurrence pattern) OR (contouring) OR (organs at risk)). In parallel, abstracts from ESTRO and ASTRO 2010-2015 were analysed and separately reviewed. The ACROP committee identified 14 European experts in close interaction with the ESTRO clinical committee who discussed and analysed the body of evidence concerning GBM target delineation.
  
  
  RESULTS
  Several key issues were identified and are discussed including (i) pre-treatment steps and immobilization, (ii) target delineation and the use of standard and novel imaging techniques, and (iii) technical aspects of treatment including planning techniques, and fractionation. Based on the EORTC recommendation focusing on the resection cavity and residual enhancing regions on T1-sequences with the addition of a 20mm margin, special situations are presented with corresponding potential adaptations depending on the specific clinical situation.
  
  
  CONCLUSIONS
  Currently, based on the EORTC consensus, a single clinical target volume definition based on postoperative T1/T2 FLAIR abnormalities is recommended, using isotropic margins without the need to cone down. A PTV margin based on the individual mask system and IGRT procedures available is advised, usually of the order of 3-5mm.
authors.affiliation: Department of Radiation Oncology, University of Munich, München, Germany.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Niyazi
authors.affiliation: Department of Molecular and Clinical Cancer Medicine, Liverpool, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Brada
authors.affiliation: Institute of Cancer Sciences, University of Glasgow, UK.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Chalmers
authors.affiliation: Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, Institut für Innovative Radiotherapy (iRT), Germany.
authors.forename: Stephanie E
authors.initials: SE
authors.lastname: Combs
authors.affiliation: Edinburgh Centre for Neuro-Oncology, University of Edinburgh, Western General Hospital, UK.
authors.forename: Sara C
authors.initials: SC
authors.lastname: Erridge
authors.affiliation: Department of Radiation Oncology, Sacro Cuore Hospital, Negrar-Verona, Italy.
authors.forename: Alba
authors.initials: A
authors.lastname: Fiorentino
authors.affiliation: Department of Radiation Oncology, University Medical Center Freiburg, Germany.
authors.forename: Anca L
authors.initials: AL
authors.lastname: Grosu
authors.affiliation: Department of Radiation Oncology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Lagerwaard
authors.affiliation: Unit of Radiation Oncology, Sant'Andrea Hospital, University of Rome Sapienza, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Minniti
authors.affiliation: Radiation Oncology, Faculty of Biology and Medicine, University of Lausanne, Switzerland.
authors.forename: René-Olivier
authors.initials: RO
authors.lastname: Mirimanoff
authors.affiliation: Department of Oncology, University of Turin, Italy.
authors.forename: Umberto
authors.initials: U
authors.lastname: Ricardi
authors.affiliation: Leeds Institute of Cancer and Pathology, St James's University Hospital, UK.
authors.forename: Susan C
authors.initials: SC
authors.lastname: Short
authors.affiliation: Center for Proton Therapy, Paul Scherrer Institute, Switzerland; University of Zürich, Switzerland.
authors.forename: Damien C
authors.initials: DC
authors.lastname: Weber
authors.affiliation: Department of Radiation Oncology, University of Munich, München, Germany.
authors.forename: Claus
authors.initials: C
authors.lastname: Belka
mesh_terms: D000328:Adult; D026683:Advisory Committees; D001932:Brain Neoplasms / Q000532:radiotherapy*; D005060:Europe; D005909:Glioblastoma / Q000532:radiotherapy*; D006801:Humans; D009364:Neoplasm Recurrence, Local; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*
keywords: ACROP; Delineation; ESTRO; Glioblastoma; Radiotherapy; Target volume