title: Dosimetric evaluation of clinical target volume in the postimplant analysis of low-dose-rate brachytherapy for prostate cancer.
abstract: OBJECTIVE
  Brachytherapy is an effective single treatment modality for low- and intermediate-risk prostate cancer. In this study, we defined a clinical target volume (CTV) and evaluated its dosimetry 1 month after the low-dose-rate brachytherapy procedure.
  
  
  METHODS
  One hundred ninety-eight consecutive patients treated for prostate cancer by iodine-125 seed brachytherapy were assessed. Prostate dosimetry was stratified according to British Columbia Cancer Agency criteria, with good implants having both V100 (percentage of target volume that receives 100% of the prescribed dose) > 85% and D90 (percentage of the prescribed dose received by 90% of the target volume) > 90%, suboptimal implants with V100 of 75-85%, or D90 80-90%, whereas poor implants were defined as those with V100 < 75 or D90 < 80%. CTV dosimetry stratification was performed according to the same dose coverage criteria, albeit to the CTV.
  
  
  RESULTS
  One hundred ninety-two patients (97%) had good prostate radiation coverage, whereas only 165 patients (83%) had good postimplant CTV dosimetry. Patients with suboptimal vs. good CTV dosimetry had prostate edema of 7.8 ± 0.2% vs. 0.2 ± 0.1%, respectively (p = 0.001).
  
  
  CONCLUSIONS
  Prostate seed implants with optimal dosimetry to prostate may still have suboptimal D90 and V100 for the CTV, especially in the presence of postimplant edema. A consensus is needed for definition and evaluation of CTV in postimplant setting for low-dose-rate prostate brachytherapy.
authors.affiliation: Department of Radiation Oncology, Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario, Canada; Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Nicola J
authors.initials: NJ
authors.lastname: Nasser
authors.affiliation: Department of Radiation Oncology, Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario, Canada.
authors.forename: Joshua
authors.initials: J
authors.lastname: Sappiatzer
authors.affiliation: Department of Radiation Physics, Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario, Canada.
authors.forename: Yinkun
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Radiation Physics, Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario, Canada.
authors.forename: Jette
authors.initials: J
authors.lastname: Borg
authors.affiliation: Department of Radiation Oncology, Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario, Canada; Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada. Electronic address: saibish.elantholi@rmp.uhn.on.ca.
authors.forename: Elantholi P
authors.initials: EP
authors.lastname: Saibishkumar
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy / Q000379:methods*; D001955:British Columbia; D005500:Follow-Up Studies; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D012189:Retrospective Studies
chemical_list: D007457:Iodine Radioisotopes
keywords: Cancer; Clinical target volume; Dosimetry; Prostate