title: MRI-based sector analysis enhances prostate palladium-103 brachytherapy quality assurance in a phase II prospective trial of men with intermediate-risk localized prostate cancer.
abstract: OBJECTIVE
  Palladium-103 ((103)Pd) may be superior to other isotopes in brachytherapy for localized intermediate-risk prostate cancer because of its relatively short half-life, higher initial dose rate, and greater dose heterogeneity within the target volume; these properties also underscore the need for accurate target delineation and postimplant quality assurance. We assessed the use of prostate sector analysis based on MRI for quality assurance after (103)Pd monotherapy.
  
  
  METHODS
  Fifty men with intermediate-risk prostate cancer underwent (103)Pd monotherapy in a prospective phase II trial at MD Anderson Cancer Center. Dosimetric analyses on day 30 after the implant were done using both CT and fused CT/MRI scans. Dosimetric variables were assessed for the entire prostate and for each of three or six sectors. Volumes and dosimetric variables were compared with paired t tests.
  
  
  RESULTS
  Postimplant dosimetric variables for the entire prostate were significantly different on CT vs. CT/MRI (p = 0.019 for V100 and p < 0.01 for D90). Prostate volumes were smaller on the CT/MRI scans (p < 0.00001). The base sector contributed the greatest difference, with doses based on CT/MRI lower than those based on CT (p < 0.01 for V100 and D90). To date, these lower base doses have not affected biochemical outcomes for patients with disease in prostate base biopsy samples.
  
  
  CONCLUSIONS
  CT/MRI is more precise than CT for prostate volume delineation and dosimetric quality assessment and thus provides superior heterogeneity control assessment after (103)Pd monotherapy implants.
authors.affiliation: Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Vinita
authors.initials: V
authors.lastname: Takiar
authors.affiliation: Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Pugh
authors.affiliation: Department of Urology, The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: David
authors.initials: D
authors.lastname: Swanson
authors.affiliation: Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Rajat J
authors.initials: RJ
authors.lastname: Kudchadker
authors.affiliation: Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Teresa L
authors.initials: TL
authors.lastname: Bruno
authors.affiliation: Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Sarah
authors.initials: S
authors.lastname: McAvoy
authors.affiliation: Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Usama
authors.initials: U
authors.lastname: Mahmood
authors.affiliation: Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX. Electronic address: sjfrank@mdanderson.org.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Frank
mesh_terms: D000328:Adult; D000368:Aged; D006801:Humans; D008297:Male; D008875:Middle Aged; D001918:Brachytherapy / Q000592:standards; D008279:Magnetic Resonance Imaging / Q000379:methods; D009367:Neoplasm Staging; D010165:Palladium / Q000627:therapeutic use; D011467:Prostate / Q000473:pathology / Q000528:radiation effects; D011471:Prostatic Neoplasms / Q000175:diagnosis / Q000532:radiotherapy; D011785:Quality Assurance, Health Care / Q000379:methods; D011868:Radioisotopes / Q000627:therapeutic use
chemical_list: D010165:Palladium; D011868:Radioisotopes
keywords: Brachytherapy; Palladium; Prostate cancer; Sector analysis