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Air kerma standard for calibration of well‐type chambers in Brazil using I 192 r HDR sources and its traceability
Author(s) -
Di Prinzio Renato,
deAlmeida Carlos Eduardo
Publication year - 2009
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3056462
Subject(s) - kerma , traceability , calibration , dosimetry , brachytherapy , nuclear engineering , nuclear medicine , medical physics , environmental science , computer science , physics , mathematics , engineering , statistics , medicine , software engineering , radiation therapy
In Brazil there are over 100 high dose rate (HDR) brachytherapy facilities using well‐type chambers for the determination of the air kerma rate ofI192 r 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.