Abstract Computed tomography (CT) has a high level of sensitivity and specificity for the diagnosis and follow-up of pathologies of the abdomen–pelvis region. Some features, such as automatic tube current modulation (ATCM), permits the acquisition of quality images with low radiation doses. This study evaluated the image quality and radiation dose of abdomen–pelvis CT protocols with ATCM technique. Were performed five CT protocols using 16-slice and 64-slice scanners, an anthropomorphic phantom for dosimetric measurements, an analytical phantom and retrospective examinations for image quality analysis. Were found significant reduction in effective dose. The highest absorbed doses were found in the stomach and spleen (56.1 and 47.2 mGy, respectively). Objective parameters as noise, low contrast and spatial resolution did not significantly differ between the protocols (p > 0.05). All protocols received the range of ‘Optimum/Acceptable’ in patient’s image quality analysis. This methodology can be reproduced in any clinical routine to optimize CT protocols.