عنوان مقاله [English]
نویسندگان [English]چکیده [English]
The increasing application of brachytherapy techniques in radiotherapy centers necessitates setting up a calibration system for the relevant radioactive sources. Accordingly, the strength of a low dose rate (LDR) 137Cs source, with specifications common to similar radioactive gamma ray sources used in afterloading brachytherapy equipment, is measured free in air in terms of air kerma by a standard spherical ionization chamber. Two different kinds of well type ionization chambers are then calibrated by the aid of the calibrated 137Cs source. The overall uncertainty of the air kerma determination of similar 137Cs sources by the calibrated well type chambers is estimated not to exceed 4%.