Implementing an exact algorithm for Helical CT:Removing the cone-beam artefacts

<p>3-dimensional computerised tomography is usually reconstructed using the naïve Feldkamp-Davis-Kress algorithm or FDK, which is not an exact reconstruction algorithm. This caus-<br> es image errors, or artefacts that appear out of the central slice, and are especially visible near edges between horizontal layers - this is demonstrated in Figure 1.<br> To overcome these artefacts; one can perform multiple scans at different heights and combine the reconstructed volumes. However, exact reconstruction methods are necessary to<br> remove them altogether. These algorithms will also reduce the scanning time which makes them very attractive. Such methods exist, and Alexander Katsevich provided an algo-<br> rithm already in 2002[1]. His algorithm uses a helical scan-geometry, rotating the X-Ray source while moving it in parallel with the rotation axis - or, equivalently, scanning the ob-<br> ject while rotating it and moving it parallel to its rotation axis. In this poster, we demonstrate that it is possible to perform and reconstruct such scans, with a Nikon XTEK scanner<br> designed for circular scans.