The use of phantom views to reduce CT streaks due to insufficient angular sampling.

An artefact that can occur in CT scans with too few views is the appearance of streaks at some distance from the sharp edge that causes them. We investigate, for parallel beam scanners, the effectiveness of the method of phantom views, as well as other methods of angular interpolation, in diminishing the view-limited streak artefact. The phantom view method consists of inserting data points obtained by interpolation in angle, along with the real data points. We show by a theoretical analysis, as well as by using simulated scans, that the phantom view method does tend to diminish the distant streaks more than other methods tested. Furthermore, we show that there is a point of diminishing returns in increasing the number of phantom views.