title: Dosimetric impact of contouring and needle reconstruction uncertainties in US-, CT- and MRI-based high-dose-rate prostate brachytherapy treatment planning.
abstract: The purpose was to evaluate the dosimetric impact of target contouring and needle reconstruction uncertainties in an US-, CT- and MRI-based HDR prostate BT treatment planning.
  
  
  
  US, CT, and MR images were acquired post-needle insertion in 22 HDR-BT procedures for 11 consecutive patients. Dose plans were simulated for an US-, CT- and MRI-based HDR-BT treatment planning procedure. Planning uncertainties in US- and CT-based plans were evaluated using MRI-based planning as reference. Target (CTVProstate) was re-contoured on MRI. Dose results were expressed in total equivalent dose given in 2Gy fractionation dose for EBRT (46Gy) plus 2 HDR-BT fractions.
  
  
  
  Uncertainties in US- and CT-based planning caused the planned CTVProstate-D90%to decrease with a mean of 2.9±5.0Gy (p=0.03) and 2.9±2.9Gy (p=0.001), respectively. The intra-observer contouring variation on MRI resulted in a mean variation of 1.6±1.5Gy in CTVProstate-D90%. Reconstruction uncertainties on US resulted in a dose variation of±3Gy to the urethra, whereas data for CT were not available for this.
  
  
  
  Uncertainties related to contouring and reconstruction in US- and CT-based HDR-BT treatment plans resulted in a systematic overestimation of the prescribed target dose. Inter-modality uncertainties (US and CT versus MR) were larger than MR intra-observer uncertainties.
authors.affiliation: Department of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark; Department of Medical Physics, Aarhus University Hospital, Aarhus, Denmark. Electronic address: susaryla@rm.dk.
authors.forename: Susanne
authors.initials: S
authors.lastname: Rylander
authors.affiliation: Department of Oncology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Simon
authors.initials: S
authors.lastname: Buus
authors.affiliation: Department of Radiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Erik M
authors.initials: EM
authors.lastname: Pedersen
authors.affiliation: Department of Oncology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Lise
authors.initials: L
authors.lastname: Bentzen
authors.affiliation: Department of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark; Department of Oncology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Kari
authors.initials: K
authors.lastname: Tanderup
mesh_terms: D001918:Brachytherapy / Q000379:methods*; D019583:Dose Fractionation, Radiation; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods; D014463:Ultrasonography / Q000379:methods; D035501:Uncertainty
keywords: CT-based brachytherapy; High-dose-rate prostate brachytherapy; Intra observer contouring variability; MRI-based brachytherapy; Prostate brachytherapy; US-based brachytherapy