Evaluation and Simulation of a New Ionization Chamber Design for use in Computed Tomography Beams

A newly-designed pencil ionization chamber with a sensitive volume of 3.4 cm³ was evaluated at the Calibration Laboratory of IPEN (São Paulo, Brazil) for use in the dosimetry of computed tomography (CT) medical equipment. The main differences between this CT ionization chamber and the commercial ones are related to the respective design and constituent materials. In the ionization chamber characterized in this work an alternative wall material was tested and a different BNC connector position was evaluated. This novel dosimeter was also designed to have an assembling process as simple and cheap as possible. To estimate the chamber performance, several pre-operational tests were undertaken. The energy dependence test was also evaluated using Monte Carlo simulation with the PENELOPE code system. In addition, Monte Carlo simulations were done to study the influence of various components on the energy deposition in its sensitive volume. The results obtained in the tests showed that the analyzed configuration of the CT ionization chamber is a good alternative for use in CT dosimetry, because it is easy to construct, and it presents a relatively low cost.