The largest and smallest X-ray computed tomography systems

As far as we know, we have applied X-ray computed tomography (CT) to the largest and the smallest objects inspected to date. The largest object is a section of a Trident C-4 rocket motor, about 2 m in diameter, which was inspected with gamma rays from a 15 MeV linear electron accelerator. Resolution of the reconstructed image is about 2 mm. Cracks 0.08 mm wide are clearly visible in the 1024 by 1024 pixel image, and contrast sensitivity is about two percent. The smallest object is a 2.5 cm diameter chest cavity of a laboratory mouse, inspected with 90 kV X-rays from a rotating anode. Spatial resolution of this image is about 0.05 mm. The heart, esophagus and lung tissue are displayed with exceptional clarity in a 512 by 512 pixel image. These results illustrate the wide range of applicability of CT techniques, and the designs of the two instruments which produced the images illustrate some of the problems which can arise when using CT for non-destructive testing. (orig.)