A standard graphite calorimeter for dosimetry in brachytherapy with high dose rate 192Ir sources

Within the framework of the JRP06 European project 'Increasing Cancer Treatment Efficacy Using 3D Brachytherapy', a prototype of a graphite standard calorimeter for the measurement of the absorbed dose rate to water, D-w, for Ir-192 sources used in high dose rate (HDR) brachytherapy has been developed at the Italian National Institute of Ionizing Radiation Metrology (ENEA-INMRI). The calorimeter was tested at the Sant' Andrea Hospital in Rome, where D-w measurements were performed in the quasi-adiabatic mode of operation using an Ir-192 MicroSelectron (R) HDR V2 source. The D-w measurements showed a reproducibility of about 1%, while the combined standard uncertainty on the D-w value at the distance of 1 cm from the source was estimated as 1.4%, lower than the uncertainty of D-w determined from the reference air-kerma rate.