Test specimens for a 3D X-ray system and method for determining the spatial resolution of a 3D X-ray system using the test specimen

A test piece 10 for determining the spatial resolution of a 3D X-ray system includes three orthogonally disposed and interconnected pulley structures 12, 14, 16 with a common center point 18, each disc structure an even number N of pyramid or truncated pyramid-shaped disk structure sectors 12- N, 14-N, 16-N having the taper to the common central point and wherein each adjacent disc structure sectors of a disc structure have different X-ray absorption properties.