Development and tests of a 30 cm pencil-type ionization chamber for dosimetry in standard and clinical CT beams

The use of computed tomography (CT) for imaging procedures is growing due to advances in the CT equipment technology. To perform the dosimetry in CT beams, the most widely used instrument is the pencil type ionization chamber with a sensitive volume length of 100 mm; however, some studies have shown that this dosimeter has underestimated the dose values. Therefore, in this study an ionization chamber with sensitive volume length of 300 mm was developed at IPEN. The characterization of this chamber was performed, and the results were obtained within the international recommended limits. As an application, the developed ionization chamber was tested in clinical beams of two different hospitals.