RESUMO
In this work a dosimetry study is presented in which the results of absorbed dose data determined under reference condition according to the IAEA TRS-398 protocol and the NCS report-2 are compared. The IAEA TRS-398 protocol for absorbed dose calibration is based on ionization chamber having an absorbed dose to water calibration factor N(D,W), while the NCS-2 report for absorbed dose calibration is based on an ionization chamber having an air- kerma calibration factor N(K). This study shows that the absorbed dose calculated with the IAEA TRS-398 formalisms is higher than that calculated with the NCS Report-2 formalism within a range of 0.4 to 0.9% in a cobalt-60 beam, and from 0.2 to 1.1% for photon beams of 6, 8 and 18 MV. The chambers used are PTW 30001, 30004, and NE-2571, which have calibration factors N(K) and N(D,W) traceable to the BIPM (Bureau International des Poids et Mesures).