A device (10) for controlling an image acquisition of a multi-slice computed tomography system (1), MSCT, is disclosed. The device comprises an input (11) for receiving projection image data from the MSCT (1), an output (12) for controlling operation of the MSCT (1) and a processor (13). The processor (13) is adapted for controlling the MSCT to acquire a large volume localizer radiograph, and for defining an organ region in the localizer radiograph that delimits an organ of interest. The processor is adapted for acquiring a large volume helical CT scan of the subject, in which an X-ray cone angle is increased when the organ region in the subject is translated into the examination volume and decreased when the organ region is translated out of the examination volume.