title: Cone-beam CT-based adaptive planning improves permanent prostate brachytherapy dosimetry: An analysis of 1266 patients.
abstract: OBJECTIVE
  To evaluate adaptive planning for permanent prostate brachytherapy and to identify the prostate regions that needed adaptation.
  
  
  METHODS
  After the implantation of stranded seeds, using real-time intraoperative planning, a transrectal ultrasound (TRUS)-scan was obtained and contoured. The positions of seeds were determined on a C-arm cone-beam computed tomography (CBCT)-scan. The CBCT-scan was registered to the TRUS-scan using fiducial gold markers. If dose coverage on the combined image-dataset was inadequate, an intraoperative adaptation was performed by placing remedial seeds. CBCT-based intraoperative dosimetry was analyzed for the prostate (D90, V100, and V150) and the urethra (D30). The effects of the adaptive dosimetry procedure for Day 30 were separately assessed.
  
  
  RESULTS
  We analyzed 1266 patients. In 17.4% of the procedures, an adaptation was performed. Without the dose contribution of the adaptation Day 30 V100 would be < 95% for half of this group. On Day 0, the increase due to the adaptation was 11.8 ± 7.2% (1SD) for D90 and 9.0 ± 6.4% for V100. On Day 30, we observed an increase in D90 of 12.3 ± 6.0% and in V100 of 4.2 ± 4.3%. For the total group, a D90 of 119.6 ± 9.1% and V100 of 97.7 ± 2.5% was achieved. Most remedial seeds were placed anteriorly near the base of the prostate.
  
  
  CONCLUSIONS
  CBCT-based adaptive planning enables identification of implants needing adaptation and improves prostate dose coverage. Adaptations were predominantly performed near the anterior base of the prostate.
authors.affiliation: Department of Medical Physics, Department of Radiation Oncology, Radiotherapiegroep behandellocatie Deventer, Nico Bolkesteinlaan 85, 7416 SE, Deventer, The Netherlands.
authors.forename: Hendrik
authors.initials: H
authors.lastname: Westendorp
authors.affiliation: Department of Radiation Oncology, Radiotherapiegroep behandellocatie Deventer, Nico Bolkesteinlaan 85, 7416 SE, Deventer, The Netherlands.
authors.forename: Carel J
authors.initials: CJ
authors.lastname: Hoekstra
authors.affiliation: Department of Radiation Oncology, Radiotherapiegroep behandellocatie Deventer, Nico Bolkesteinlaan 85, 7416 SE, Deventer, The Netherlands.
authors.forename: Jos J
authors.initials: JJ
authors.lastname: Immerzeel
authors.affiliation: Department of Radiation Oncology, Radiotherapiegroep behandellocatie Deventer, Nico Bolkesteinlaan 85, 7416 SE, Deventer, The Netherlands.
authors.forename: Sandrine M G
authors.initials: SM
authors.lastname: van de Pol
authors.affiliation: Department of Radiation Oncology, Radiotherapiegroep behandellocatie Deventer, Nico Bolkesteinlaan 85, 7416 SE, Deventer, The Netherlands.
authors.forename: Charles G H J
authors.initials: CG
authors.lastname: Niël
authors.affiliation: Department of Radiation Oncology, Radiotherapiegroep behandellocatie Deventer, Nico Bolkesteinlaan 85, 7416 SE, Deventer, The Netherlands.
authors.forename: Robert A J
authors.initials: RA
authors.lastname: Kattevilder
authors.affiliation: Department of Medical Physics, Department of Radiation Oncology, Radiotherapiegroep behandellocatie Deventer, Nico Bolkesteinlaan 85, 7416 SE, Deventer, The Netherlands.
authors.forename: Tonnis T
authors.initials: TT
authors.lastname: Nuver
authors.affiliation: Department of Medical Physics, Department of Radiation Oncology, Radiotherapiegroep behandellocatie Deventer, Nico Bolkesteinlaan 85, 7416 SE, Deventer, The Netherlands.
authors.forename: André W
authors.initials: AW
authors.lastname: Minken
authors.affiliation: Department of Medical Physics, Department of Radiation Oncology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands.
authors.forename: Marinus A
authors.initials: MA
authors.lastname: Moerland
mesh_terms: D001918:Brachytherapy; D054893:Cone-Beam Computed Tomography; D006801:Humans; D007432:Intraoperative Period; D008297:Male; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D011874:Radiometry; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*
keywords: I-125; adaptive dosimetry; adaptive radiotherapy; brachytherapy; prostate