X-ray CT system

An X-ray CT system is provided to achieve simplification and time-saving in the work of setting the subject in scanning position. An X-ray CT system as an embodiment comprises a patient table, a gantry apparatus, a formation unit, a drive unit, a storage unit, and a drive controller. The patient table has a top plate, on which the subject is placed. The gantry apparatus executes scanning on the subject by rotating a detector unit, which includes an X-ray tube and an X-ray detector set facing each other. The formation unit forms image data of the subject based on the data acquired by the scanning. The drive unit changes the relative position between the top plate and the detector unit. The storage unit stores relative position information that indicates the relative position applied for the scanning. When a new scanning session is to be performed, the drive controller controls the drive unit to set the top plate and the detector unit at the relative position indicated by the stored relative position information.