Study on reconstructed image of 3D cone-beam CT scanner

We have calculated the intensity distribution of scatter radiation as well as primary radiation on a two-dimensional detector plane in a cone-beam x-ray three-dimensional CT scanner, using Monte Carlo method. From the two-dimensional projections including the scatter radiation arising in cylindrical water phantoms for various conditions, we have reconstructed 3D images by cone-beam reconstruction techniques and have evaluated the effects of scatter on reconstructed images. The effects of wedge filter, which make the primary x-ray intensity uniform on a detector plane, on the scatter intensity distribution have been examined. With the filter, the scatter to primary ratio at the center of the projection reduce by half compared to that without the filter and cupping artifacts in reconstructed image are eliminated. Furthermore, the usage of the filter decreases in absorbed dose of about 60% to without filter.