How does it work?
In comparison to a conventional x-ray, which uses a fixed x-ray tube, a CT scanner uses a motorised x-ray source that shoots x-rays as it rotates around the body. Special detectors are located directly opposite the x-ray source and each time the x-ray source completes one full rotation, a computer then produces a 2D image or a ‘slice’ of the patient. In a 16-slice scanner there are 16 detectors and thus each revolution actually acquires 16 slices simultaneously.
When a full slice is completed, the image is stored, the motorised bed moved forward incrementally, and the process is repeated to produce another image slice. This process continues until the desired number of slices is collected. A full body CT can be acquired in less than one minute in most patients.