title: Uncertainties of target volume delineation in MRI guided adaptive brachytherapy of cervix cancer: a multi-institutional study.
abstract: OBJECTIVE
  We aimed to quantify target volume delineation uncertainties in cervix cancer image guided adaptive brachytherapy (IGABT).
  
  
  METHODS
  Ten radiation oncologists delineated gross tumour volume (GTV), high- and intermediate-risk clinical target volume (HR CTV, IR CTV) in six patients. Their contours were compared with two reference delineations (STAPLE-Simultaneous Truth and Performance Level Estimation and EC- expert consensus) by calculating volumetric and planar conformity index (VCI and PCI) and inter-delineation distances (IDD).
  
  
  RESULTS
  VCISTAPLE and VCIEC were 0.76 and 0.72 for HR CTV, 0.77 and 0.68 for IR CTV and 0.59 and 0.58 for GTV. Variation was most prominent caudally and cranially in all target volumes and posterolaterally in IR CTV. IDDSTAPLE and IDDEC for HR CTV (3.6±3.5 and 3.8±3.4 mm) were significantly lower than for GTV (4.8±4.2 and 4.2±3.5 mm) and IR CTV (4.7±5.2 and 5.2±5.6 mm) (p<0.05).
  
  
  CONCLUSIONS
  Due to lower delineation uncertainties when compared to GTV and IR CTV, HR CTV may be considered most robust volume for dose prescription and optimization in cervix cancer IGABT. Adequate imaging, training and use of contouring recommendations are main strategies to minimize delineation uncertainties.
authors: Radiation Oncology Department, National Center for Cancer Care and Research, Doha, Qatar. ppetric@hmc.org.qa
authors: Primož
authors: P
authors: Petrič
authors: Robert
authors: R
authors: Hudej
authors: Peter
authors: P
authors: Rogelj
authors: Mateja
authors: M
authors: Blas
authors: Kari
authors: K
authors: Tanderup
authors: Elena
authors: E
authors: Fidarova
authors: Christian
authors: C
authors: Kirisits
authors: Daniel
authors: D
authors: Berger
authors: Johannes Carl Athanasios
authors: JC
authors: Dimopoulos
authors: Richard
authors: R
authors: Pötter
authors: Taran Paulsen
authors: TP
authors: Hellebust
mesh_terms: D001918:Brachytherapy / Q000379:methods*; D005260:Female; D006801:Humans; D053783:Magnetic Resonance Imaging, Interventional / Q000379:methods*; D011446:Prospective Studies; D011879:Radiotherapy Dosage; D061089:Radiotherapy, Image-Guided / Q000379:methods*; D047368:Tumor Burden; D035501:Uncertainty; D002583:Uterine Cervical Neoplasms / Q000473:pathology / Q000532:radiotherapy*