title: Multicentre treatment planning study of MRI-guided brachytherapy for cervical cancer: comparison between tandem-ovoid applicator users.
abstract: OBJECTIVE
  To compare MRI-guided treatment planning approaches between four centres that use tandem-ovoid applicators.
  
  
  METHODS
  Four centres generated three treatment plans for four patients: standard, optimised intracavitary, and optimised intracavitary/interstitial. Prescribed D90 High-Risk CTV (HR-CTV) was 85 Gy EQD2 (external-beam radiotherapy and brachytherapy), while the D(2cc) OAR limit was 90 Gy EQD2 for bladder and 75 Gy EQD2 for rectum, sigmoid, and bowel, respectively. DVH-parameters, source loading patterns and spatial dose distributions of the three treatment plans were compared.
  
  
  RESULTS
  The standard plans of the different centres were comparable with respect to the D90 HR-CTV, but differed in OAR doses. MRI-guided intracavitary optimisation resulted in organ sparing and smaller variation in DVH parameters between the centres. Adding interstitial needles led to target dose escalation while respecting the OAR constraints. However, substantial differences in relative weights of the applicator parts resulted in an increased variation in DVH parameters and locations of high dose regions.
  
  
  CONCLUSIONS
  MRI-guided brachytherapy treatment planning optimisation provides the possibility to increase the dose to the HR-CTV and spare the OARs. Depending on the degree of conformity the centres make different choices in relative weighting of applicator parts, leading to different dose distributions.
authors.affiliation: University Medical Centre Utrecht, The Netherlands. c.nomden@umcutrecht.nl
authors.forename: Christel N
authors.initials: CN
authors.lastname: Nomden
authors.forename: Astrid A C
authors.initials: AA
authors.lastname: de Leeuw
authors.forename: Erik
authors.initials: E
authors.lastname: Van Limbergen
authors.forename: Marisol
authors.initials: M
authors.lastname: de Brabandere
authors.forename: An
authors.initials: A
authors.lastname: Nulens
authors.forename: Remi A
authors.initials: RA
authors.lastname: Nout
authors.forename: Mirjam
authors.initials: M
authors.lastname: Laman
authors.forename: Martijn
authors.initials: M
authors.lastname: Ketelaars
authors.forename: Ludovicus
authors.initials: L
authors.lastname: Lutgens
authors.forename: Brigitte
authors.initials: B
authors.lastname: Reniers
authors.forename: Ina Maria
authors.initials: IM
authors.lastname: Jürgenliemk-Schulz
mesh_terms: D001918:Brachytherapy / Q000295:instrumentation* / Q000379:methods; D005260:Female; D006801:Humans; D053783:Magnetic Resonance Imaging, Interventional / Q000379:methods*; D058958:Organs at Risk; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D061089:Radiotherapy, Image-Guided / Q000379:methods*; D002583:Uterine Cervical Neoplasms / Q000473:pathology / Q000532:radiotherapy*