An imaging apparatus for use with an imaging device in order to image a subject. The imaging device includes an annular gantry having an opening and a table to accommodate the subject or a portion thereof for imaging. The imaging apparatus includes a platform and a positioning device. The imaging device is mounted to the platform. The annular gantry is in a fixed position relative to the platform. The table is horizontally displaceable relative to the annular gantry. The positioning device supports the platform and is configured to horizontally displace the platform relative to a supporting surface for the subject. The positioning device is configured to position the platform with the imaging device in at least one operational state in such a way that, during a relative movement of the table with respect to the annular gantry, the table remains stationary relative to the supporting surface.