CT scanning down to 0.1 micron resolution is a vital tool in validating a part or assembly.  Not only goes CT scanning eliminate GR&R variability and create a high resolution point cloud of the part that can be compared to the original CAD model to see all dimensions, not just toleranced dimensions on a drawing, it creates a life long part retain.  Time, temperature, packaging of a physical part will never change the high resolution point cloud.  So parts from year 1 and year 10 can be compared.  Also, since the part can be x-rayed we can get internal dimensions without destructive sectioning that can warp dimensions.