A CT scan is a method of obtaining a CT image. There are two methods: one is to rotate the object and perform a CT projection, and the other is to turn the radiation source and detector around the object and perform a CT projection. In industrial CT scan systems, the object is often placed on a turntable and rotated. In medical CT scan systems, a radiation source and an x-ray detector rotate around the human body to produce a CT projection. In both cases, a set of CT projection data taken at different angles is reconstructed by a computer and converted into a CT image.