title: Centralized multiinstitutional postimplant analysis for interstitial prostate brachytherapy.
abstract: OBJECTIVE
  To investigate the feasibility and utility of performing centralized postimplant analysis for transperineal interstitial permanent prostate brachytherapy (TIPPB) by conducting a pilot study that compares the results obtained from 125I implants conducted at five different institutions.
  
  
  METHODS
  Dose-volume histogram (DVH) analysis was performed on 10 postimplant CT scans from each of five institutions. This analysis included the total implanted activity of 125I, ultrasound, and CT volumes of the prostate, target-volume ratios, dose homogeneity quantifiers, prostate dose coverage indices, and rectal doses. As a result of the uncertainty associated with the delineation of the prostatic boundaries on a CT scan, the contours were redrawn by a single, study center physician, and a repeat DVH analysis was performed. This provided the basis for comparison between institutions in terms of implant technique and quality.
  
  
  RESULTS
  By comparing total activity to preimplant ultrasound volume we clearly demonstrated that differences exist in implant technique among these five institutions. The difficulty associated with determining glandular boundaries on CT scans was apparent, based upon the variability in prostate volumes drawn by the various investigators compared to those drawn by the study center physician. This made no difference, of course, in the TVR or homogeneity quantifiers that are independent of target location. Furthermore, this variability made surprisingly little difference in terms of dose coverage of the prostate gland. Rectal doses varied between institutions according to the various implant techniques.
  
  
  CONCLUSIONS
  Centralized, outcome-based evaluation of transperineal interstitial permanent prostate brachytherapy is viable and appropriate. Such an approach could be reasonably used in the conduct of multiinstitutional trials used to study the efficacy of the procedure.
authors.affiliation: Radiation Oncology Service, Wilford Hall Medical Center, Lackland AFB, TX, USA.
authors.forename: W S
authors.initials: WS
authors.lastname: Bice
authors.forename: B R
authors.initials: BR
authors.lastname: Prestidge
authors.forename: P D
authors.initials: PD
authors.lastname: Grimm
authors.forename: J L
authors.initials: JL
authors.lastname: Friedland
authors.forename: V
authors.initials: V
authors.lastname: Feygelman
authors.forename: M
authors.initials: M
authors.lastname: Roach
authors.forename: J J
authors.initials: JJ
authors.lastname: Prete
authors.forename: D F
authors.initials: DF
authors.lastname: Dubois
authors.forename: J C
authors.initials: JC
authors.lastname: Blasko
mesh_terms: D001918:Brachytherapy / Q000379:methods / Q000592:standards*; D005240:Feasibility Studies; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008297:Male; D010865:Pilot Projects; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D014463:Ultrasonography
chemical_list: D007457:Iodine Radioisotopes