A calculating unit for calculating a recording trajectory of a CT system has a receive interface, an optimizer and a control unit. The receive interface serves for receiving measurement and simulation data relative to the object to be recorded. The optimizer is configured to determine the recording trajectory based on known degrees of freedom of the CT system, based on the measurement and simulation data and based on a test task from a group having a plurality of test tasks. The control unit is configured to output data in correspondence with the recording trajectory for controlling the CT system.