title: Air kerma standard for calibration of well-type chambers in Brazil using 192Ir HDR sources and its traceability.
abstract: In Brazil there are over 100 high dose rate (HDR) brachytherapy facilities using well-type chambers for the determination of the air kerma rate of 192Ir sources. This paper presents the methodology developed and extensively tested by the Laboratorio de Ciencias Radiologicas (LCR) and presently in use to calibrate those types of chambers. The system was initially used to calibrate six well-type chambers of brachytherapy services, and the maximum deviation of only 1.0% was observed between the calibration coefficients obtained and the ones in the calibration certificate provided by the UWADCL. In addition to its traceability to the Brazilian National Standards, the whole system was taken to the University of Wisconsin Accredited Dosimetry Calibration Laboratory (UWADCL) for a direct comparison and the same formalism to calculate the air kerma was used. The comparison results between the two laboratories show an agreement of 0.9% for the calibration coefficients. Three Brazilian well-type chambers were calibrated at the UWADCL, and by LCR, in Brazil, using the developed system and a clinical HDR machine. The results of the calibration of three well chambers have shown an agreement better than 1.0%. Uncertainty analyses involving the measurements made both at the UWADCL and LCR laboratories are discussed.
authors.affiliation: Laboratorio de Ciencias Radiologicas-Universidade do Estado do Rio de Janeiro, R. São Francisco Xavier, 524, Pavilhão Haroldo Lisboa da Cunha, Térreo, Sala 136-Maracanã, CEP 20550-900-Rio de Janeiro/RJ-Rio de Janeiro, RJ, Brazil. rprinzio@cnen.gov.br
authors.forename: Renato
authors.initials: R
authors.lastname: Di Prinzio
authors.forename: Carlos Eduardo
authors.initials: CE
authors.lastname: DeAlmeida
mesh_terms: D000388:Air; D055592:Biophysical Phenomena; D001918:Brachytherapy / Q000592:standards* / Q000706:statistics & numerical data; D001938:Brazil; D006801:Humans; D007496:Iridium Radioisotopes / Q000008:administration & dosage / Q000627:therapeutic use; D011874:Radiometry / Q000295:instrumentation / Q000592:standards* / Q000706:statistics & numerical data; D011880:Radiotherapy Planning, Computer-Assisted / Q000706:statistics & numerical data; D012015:Reference Standards; D012542:Scattering, Radiation
chemical_list: D007496:Iridium Radioisotopes