An imaging procedure in radiology is computer tomography, short CT.
The test object is placed hereby on a turntable between an X-ray source and a high-resolution area detector. From the step-by-step 360 degree rotating test object, a 2D projection image is taken for each angular position. A powerful software calculates from these images the absorption behavior for each location in the test object.
The absorption behavior is visualized at each volume element (voxel) with gray values. Each gray value represents a different material density. Finally, these single elements are assembled into a 3D solid model.
The process is used in the plastics industry to determine the exact dimensions of a part, making it easier to identify tolerances that differ from the desired geometry.
Furthermore it is possible to cut through the part to identify defects on the inside (e.g. voids).