Utilization of a small volume ionization chamber in computed tomography

Abstract

The dosimetric protocol currently used has become inadequate since the advancement of multislice computed tomography. Considering this fact and recent studies that show that, the contribution of computed tomography for the collective effective dose is larger than other radiological procedures, it is necessary to define new measuring procedures and to use new detectors and phantoms. This study aimed to test the viability of using an unusual dosimeter since the pencil ion chamber, which has been used since few decades, is considered inappropriate to the new characteristics of the computed tomography beams. Therefore, tests were performed on a PMMA phantom using a small volume ion chamber with active length of 23 mm and a 100-mm-long pencil chamber. The phantom was constructed locally and it was based on the computed tomography phantom proposed by international recommendations. The comparison of tests results from both types of dosimeters (small volume ion chamber and pencil ion chamber) indicates the viability of using unusual dosimeters to perform measures computed tomography beams.