title: Inverse automated treatment planning with and without individual optimization in interstitial permanent prostate brachytherapy with high- and low-activity 125I.
abstract: OBJECTIVE
  To determine whether dose distribution achieved with treatment plans using high- and low-activity (125)I implants differs.
  
  
  METHODS
  Based on intraoperative transrectal ultrasound scans of 71 patients, inverse automated treatment plans (IATP) were performed with 15.5-kBq (0.42-mCi) and 25.2-kBq (0.68-mCi) (125)I implants using a commercial 3-D planning system (Variseed). A prescription dose of 145 Gy in 98% of the prostate volume (V100), a maximum dose to the urethra of 250 Gy (D1), and a maximum dose to 10% of the anterior rectal wall of 145 Gy (D10) were required. The plans were manually corrected, if necessary.
  
  
  RESULTS
  In the IATP, a better dose coverage of the prostate was found for high-activity seeds (V100 of 98% vs 84%). The prostate dose values increased with the prostate volume. After manual optimization, the differences were only marginal with a prostate V100 of 99% for both activities, a urethra D1 of 247 Gy and 239 Gy, and a rectum D10 of 135 Gy and 124 Gy for high- and low-activity seeds. Low-activity seeds required more sources (66 vs 47) and needles (24 vs 17; all numbers are median values).
  
  
  CONCLUSIONS
  Concerning the prostate dose coverage, high-activity seeds are superior in the IATP. After manual adjustment, the dose values for the prostate and the organs at risk are similar. Considering a supposedly decreased toxicity and a shorter implantation time for a lower number of seeds, we recommend high-activity seeds for experienced teams.
authors.affiliation: Department of Radiotherapy, University Hospital, RWTH Aachen, Germany. Michael.Pinkawa@post.rwth-aachen.de
authors.forename: Michael
authors.initials: M
authors.lastname: Pinkawa
authors.forename: Uwe
authors.initials: U
authors.lastname: Maurer
authors.forename: Andrew
authors.initials: A
authors.lastname: Mulhern
authors.forename: Bernd
authors.initials: B
authors.lastname: Gagel
authors.forename: Thomas
authors.initials: T
authors.lastname: Block
authors.forename: Holger
authors.initials: H
authors.lastname: Borchers
authors.forename: Johannes
authors.initials: J
authors.lastname: Grieger
authors.forename: Thomas
authors.initials: T
authors.lastname: Henkel
authors.forename: Michael
authors.initials: M
authors.lastname: Eble
mesh_terms: D001918:Brachytherapy / Q000379:methods*; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D011467:Prostate / Q000033:anatomy & histology; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy* / Q000601:surgery; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012044:Regression Analysis; D014463:Ultrasonography; D014521:Urethra / Q000528:radiation effects
chemical_list: D007457:Iodine Radioisotopes