Development of phantom for current modulation quality assurance test on computed tomography.

Automatic tube current modulation (ATCM) in computed tomography (CT) is a powerful tool for reducing the dose delivery to the patient during the scan. A phantom is used to perform the ATCM quality control (QC) test, assessing how the CT system adapts the tube current as a function of object size. Considering quality assurance recommendations (Brazilian and international), we developed a dedicated phantom for the ATCM test. The phantom was built-in high-density polyethylene in a cylindric shape with three different sizes. To verify the applicability of this phantom, we tested it in two different CT scanners (Toshiba and Philips). The results demonstrated concordance between a discrete change in phantom size, and the corresponding change in the tube current, indicating that the CT system could adapt current when a discrete attenuation shift occurred. The developed phantom might be used in ATCM QC tests.