X-RAY MICROTOMOGRAPHY SCANNER USING TIME-DELAY INTEGRATION FOR ELIMINATION OF RING ARTIFACTS IN THE RECONSTRUCTED IMAGE

Most X-ray microtomography scanners work on the same principle as thir d-generation medical CT scanners, that is, the same point in each proj ection is measured by the same detector element. This leads to ring ar tefacts in the reconstructed image if the X-ray sensitivities of the i ndividual detector elements, after any analytical correction, are not all identical. We have developed an X-ray microtomography scanner whic h uses the time-delay integration method of imaging with a CCD detecto r to average the characteristics of all the detector elements in each linear projection together. This has the added advantage of allowing s pecimens which are larger than the detector and X-ray field to be scan ned. The device also uses a novel mechanical stage to ''average out'' inhomogeneities in the X-ray field. The results show that ring artefac ts in microtomographic images are eliminated using this technique.