Some characterization tests for an extrapolation chamber in CT standard beams in a specific chamber depth

Abstract

Among all diagnostic exams, the computed tomography (CT) is responsible for the highest dose values to the patients. So, the radiation doses in this procedure must be accurate for the dosimetry procedure in CT scanner beams making use of pencil ionization chambers with sensitive volume lengths of 10 cm. However, there is no primary standard system for this kind of radiation beam. An extrapolation ionization chamber, built at the Cali-bration Laboratory (LCI) was tested to establish a CT primary standard. The aim of this work was to perform some characterization tests (short- and medium-term stabilities, energy dependence, angular dependence) in the standard X-ray beams established for computed tomography at the LCI in a specific chamber depth (1.25 mm). The results showed to be within the international recommended limits except for the energy dependence.