title: Prevention of needle displacement in multifraction high-dose-rate prostate brachytherapy: A prospective volumetric analysis and technical considerations.
abstract: OBJECTIVE
  We conducted a prospective study to evaluate needle displacements between prostate high-dose-rate (HDR) brachytherapy fractions and offer technical recommendations to help prevent displacements from the outset.
  
  
  METHODS
  Planning computed tomography and verification computed tomography scans were obtained at 1-mm slice thickness and prospectively assessed for interfraction needle movement for each fraction of a 2-fraction HDR prostate boost. For both the planning and verification CTs, distances from each needle tip to the centroid of 3 implanted prostate gold seeds were measured. We determined the mean and range of the displacement distances.
  
  
  RESULTS
  Thirty-three consecutive patients (66 fractions, 540 needle-pair positions for a total of 1080 needles) were evaluated for changes in the length between the needle tip and centroid displacement. Overall, only 0.2% of the needles had any change greater than 3.5 mm between the needle tip and centroid. The mean amount of displacement was 0.97 mm, with a standard deviation of 0.76 mm. Among the patients, no fraction had more than 1 needle with a variation greater than 3.0 mm.
  
  
  CONCLUSIONS
  Needle displacements in HDR prostate brachytherapy have been reported by numerous institutions using various techniques. We report the first study to demonstrate needle displacement of less than 1 mm on average, and we describe our process of care surrounding the implantation.
authors.affiliation: Penrose Cancer Center, Radiation Oncology, Colorado Springs, Colorado. Electronic address: AnujPeddada@Centura.Org.
authors.forename: Anuj V
authors.initials: AV
authors.lastname: Peddada
authors.affiliation: Penrose Cancer Center, Colorado Associates in Medical Physics, Colorado Springs, Colorado.
authors.forename: Olivier C
authors.initials: OC
authors.lastname: Blasi
authors.affiliation: Penrose Cancer Center, Colorado Associates in Medical Physics, Colorado Springs, Colorado.
authors.forename: Gerald A
authors.initials: GA
authors.lastname: White
authors.affiliation: Penrose Cancer Center, Radiation Oncology, Colorado Springs, Colorado.
authors.forename: Alan T
authors.initials: AT
authors.lastname: Monroe
authors.affiliation: Colorado Springs Health Partners, Urology, Colorado Springs, Colorado.
authors.forename: Scott B
authors.initials: SB
authors.lastname: Jennings
authors.affiliation: Penrose Cancer Center, Colorado Associates in Medical Physics, Colorado Springs, Colorado.
authors.forename: Greg L
authors.initials: GL
authors.lastname: Gibbs
mesh_terms: D001918:Brachytherapy / Q000379:methods*; D006801:Humans; D008297:Male; D009339:Needles; D011446:Prospective Studies; D011467:Prostate / Q000000981:diagnostic imaging; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed