title: Dosimetric characterization of radioactive sources employed in prostate cancer therapy.
abstract: OBJECTIVE
  Three types of radiation sources are employed currently in the radiation treatment of prostate cancer, namely, external, implant, and high-dose-rate (HDR) sources using an afterloader method. The present article provides a detailed dosimetric characterization of several commercially available implant sources and an HDR source employing the same stochastic code and dataset.
  
  
  METHODS
  The radioactive implants considered are (125)I seeds: models 6701, 6702 and 6711, (103)Pd seed: model 200, and a high-dose-rate (192)Ir source: microSelectron-HDR model V7.0x. Detailed modeling of the sources and their associated X-rays and gamma rays has been carried out using the stochastic code MCNP4C. A sensitivity study has been conducted to quantify effects of varying the composition and density of the tissue equivalent material, and a dosimetric comparison is made for different media (tissue equivalent, solid-water, water, and air). Furthermore, a set of measurements using thermoluminescent dosimeters has been done to provide experimental validation of some of the calculational results obtained.
  
  
  RESULTS
  Effectively, high-precision dosimetric values (Monte-Carlo statistical 1-sigma error <1%) are provided in tabulated form over a wide range to enable therapy planning as well as to check numerical values calculated by other methods. A subset of calculated dosimetric values has been experimentally validated by using thermoluminescent dosimeters.
  
  
  CONCLUSIONS
  A detailed comparison of results obtained for the radial dose distribution function, anisotropy factor, and dose rate constant as defined in the TG-43 protocol has indicated reasonable agreement with the values reported in the literature.
authors.affiliation: Polytechnic Federal School of Lausanne, Institute of the Energy of Physics & Particles, Reactor Physics and Systems Laboratory, CH-1015 Lausanne, Switzerland.
authors.forename: Valery Olivier
authors.initials: VO
authors.lastname: Zilio
authors.forename: Om Parkash
authors.initials: OP
authors.lastname: Joneja
authors.forename: Youri
authors.initials: Y
authors.lastname: Popowski
authors.forename: Rakesh
authors.initials: R
authors.lastname: Chawla
mesh_terms: D001918:Brachytherapy / Q000295:instrumentation*; D003198:Computer Simulation; D006801:Humans; D007457:Iodine Radioisotopes / Q000592:standards / Q000627:therapeutic use; D007496:Iridium Radioisotopes / Q000592:standards / Q000627:therapeutic use; D008297:Male; D010165:Palladium / Q000592:standards / Q000627:therapeutic use; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011868:Radioisotopes / Q000592:standards* / Q000627:therapeutic use; D011874:Radiometry; D011881:Radiotherapy, Computer-Assisted
chemical_list: D007457:Iodine Radioisotopes; D007496:Iridium Radioisotopes; D011868:Radioisotopes; D010165:Palladium