[en] In this work, a multiphase phantom capable to be setting with solid, liquid and gas was testing using the third-generation industrial computed tomography developed at CTR/IPEN. The phantom is cylindrical piece of 170 mm diameter and 240 mm height built in polymethylmethacrylate, iron, aluminum with a empty hole. Gamma ray tomography experiments were carried with the empty hole phantom and with the water filled hole phantom to measure the capability to distinguish the phases, especially the air and the water. In this work the scanner was setting for 90 views and 19 projections for each detector totalizing 11970 projections. The results were reconstructed using the Alternative Minimization algorithm in 60x60 pixels images. Experiments to determine the linear attenuation coefficients of the phantom were carried applying the Lambert-Beer principle. Results shown that was possible to distinguish between the phases even the polymethylmethacrylate and the water have very similar density and linear attenuation coefficients. It was established that the newly developed third generation fan-beam arrangement gamma scanner unit has a good spatial resolution acceptable given the size of the phantom used in this study.(author)