03 Protection Doses Standardization for metrological applications

This work accurately determined the radiation dose in radiation protection range using a PTW primary standard chamber model TN 32008. The characterization of the ion chamber used was performed at different radiation beam qualities. The performance of the chamber as a primary standard was studied in 137 Cs gamma source where the unit of absorbed dose in Gray was determined from its definition. Factors affecting the dose calculation such as operating voltage, saturation, and ion recombination were studied at the optimum conditions of the chamber usage. Moreover, the performance of the chamber as a primary standard dosemeter was extensively studied using the 60 Co gamma source and different X-ray beam qualities where the relation between its dose-to-collected charge (Gy/C) using the photon energy (keV) was determined. The detailed uncertainty budget was calculated for the used beam qualities. It was found that the chamber can be used in direct radiation dose determination as a primary standard chamber for wide photon energies from 42 keV (effective energy of 100 kV X-ray) to 1250 keV (60 Co) considering the relative stopping power of graphite to air correction and the relative attenuation of the precise beam quality to that of Cs-137 source. The uncertainty of the chamber Nk is 0.7% which shows an energy dependency.