The influence of scattered radiation on the CT numbers of bone on a scanner with a fixed detector array

A dependence of the CT number upon radial position of a bone plug in a unit density phantom is observed with a scanner employing a fixed detector array. The effect of the signal produced by scattered radiation from the phantom is analysed. A scatter correction consisting of a fixed fraction of the incident x-ray intensity is considered. The resultant error from such a correction is found to depend upon the ratio of the scatter to the primary detected intensities and is shown to be consistent with the observed results.