3D CT scanning during spinal surgery. Surgeon analysing a patient's spine using a Siemens ARCADIS Orbic 3D unit. This equipment is used to produce a three dimensional computed tomography (CT) scan of the problematic bones and joints of the patient. The scans are shown as a real-time video that is observed by the surgeon as he operates. In this case, the surgeon may be scanning the patient to check that their spinal supports (seen as dark lines on the left screen) are aligned correctly.