A method for performing at least two pre-scans while rotating a rotating gantry of an imaging system about an examination region during the same scan, said imaging system comprising a radiation source emitting radiation through the examination region and comprising a radiation source controller configured to control the radiation source, including activating and deactivating emission of radiation and the imaging system further comprising an annular ring of radiation attenuating material and material free regions or holes at desired angular positions, the annular ring being temporarily and stationary affixed to the imaging system, wherein emitted radiation only traverses the examination region when a path of the emitted radiation from the radiation source aligns with a hole in the annular ring, the method comprising: determining start and end pre-scan positions of a subject support carrying a subject to be imaged; identifying at least a first angle of rotation of the rotating gantry at which a first pre-scan is acquired and a second angle of rotation of the rotating gantry at which a second pre-scan is acquired, wherein the first and the second angles of rotation are different angles, and the first and second angles are separated from each other by a non-zero angular range during which radiation does not traverse the examination region by means of the radiation source controller; acquiring data, via the imaging system while rotating the rotating gantry, only during a predetermined angular range about the first angle of rotation for a first plurality of rotations from the start to the end pre-scan positions and during the predetermined angular range about the second angle of rotation for a second plurality of rotations from the start to the end pre-scan positions; and reconstructing the first pre-scan based only on the data acquired during the predetermined angular range about the first angle of rotation and the second pre-scan based only on the data acquired during the predetermined angular range about the second angle of rotation. determining start and end pre-scan positions of a subject support carrying a subject to be imaged; identifying at least a first angle of rotation of the rotating gantry at which a first pre-scan is acquired and a second angle of rotation of the rotating gantry at which a second pre-scan is acquired, wherein the first and the second angles of rotation are different angles, and the first and second angles are separated from each other by a non-zero angular range during which radiation does not traverse the examination region by means of the radiation source controller; acquiring data, via the imaging system while rotating the rotating gantry, only during a predetermined angular range about the first angle of rotation for a first plurality of rotations from the start to the end pre-scan positions and during the predetermined angular range about the second angle of rotation for a second plurality of rotations from the start to the end pre-scan positions; and reconstructing the first pre-scan based only on the data acquired during the predetermined angular range about the first angle of rotation and the second pre-scan based only on the data acquired during the predetermined angular range about the second angle of rotation.