title: Dosimetry of permanent interstitial prostate brachytherapy for an interoperative procedure, using O-arm based CT and TRUS.
abstract: OBJECTIVE
  The aim of this report is dosimetric evaluation for an intraoperative fusion computed tomography (CT) as a superior predictor of 1-month CT based dosimetry in comparison to transrectal ultrasound (TRUS) in permanent interstitial prostate brachytherapy.
  
  
  METHODS
  Data of 65 patients treated with seed implantation were analyzed. All procedures has been performed with patients in the lithotomy position inside the O-arm system. An end-fine probe is used as a landmark to fuse TRUS and O-arm-based CT images. There was no difference in the patient's position, probe position, and timing of image acquisition between the two imaging modalities. Dose-volume histogram (DVH) parameters such as the dose to 90% of prostate volume (D90) has been analyzed.
  
  
  RESULTS
  The area under the curve of the receiver operating characteristic tended to be larger on fusion CT than on TRUS for most DVH parameters (71.85% vs. 59.59% for D90; p = 0.07). Significant relationships between fusion CT and 1-month CT were confirmed using Pearson's correlation coefficients for most DVH parameters (R = 0.48, p < 0.01 for D90), although the relationship between TRUS and 1-month CT was poor. Large dose reduction (35 Gy for D90) was seen from TRUS to fusion CT, especially in patients with high body weight and small prostate volume.
  
  
  CONCLUSIONS
  Intraoperative fusion CT appears to have higher predictive power for 1-month CT-based dosimetry than TRUS. A prospective trial using fusion CT-based planning is warranted.
authors.affiliation: Department of Radiology and Radiation Oncology.
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Ishiyama
authors.affiliation: Department of Radiology and Radiation Oncology.
authors.forename: Akane
authors.initials: A
authors.lastname: Sekiguchi
authors.affiliation: Department of Urology, Kitasato University School of Medicine, Kitasato, Sagamihara, Japan.
authors.forename: Takefumi
authors.initials: T
authors.lastname: Satoh
authors.affiliation: Department of Urology, Kitasato University School of Medicine, Kitasato, Sagamihara, Japan.
authors.forename: Hideyasu
authors.initials: H
authors.lastname: Tsumura
authors.affiliation: Department of Radiology and Radiation Oncology.
authors.forename: Kouji
authors.initials: K
authors.lastname: Takenaka
authors.affiliation: Department of Radiology and Radiation Oncology.
authors.forename: Shogo
authors.initials: S
authors.lastname: Kawakami
authors.affiliation: Department of Urology, Kitasato University School of Medicine, Kitasato, Sagamihara, Japan.
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Tabata
authors.affiliation: Department of Urology, Kitasato University School of Medicine, Kitasato, Sagamihara, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Kobayashi
authors.affiliation: Department of Urology, Kitasato University School of Medicine, Kitasato, Sagamihara, Japan.
authors.forename: Masatsugu
authors.initials: M
authors.lastname: Iwamura
authors.affiliation: Department of Radiology and Radiation Oncology.
authors.forename: Kazushige
authors.initials: K
authors.lastname: Hayakawa
keywords: O-arm system; brachytherapy; intraoperative CT; low dose rate; prostate cancer