Studies on implementation of the Katsevich algorithm for spiral cone-beam CT

Recently, Katsevich proposed the first exact helical cone-beam reconstruction algorithm that takes longitudinally truncated data collected from part of a scanning turn. A key theoretical basis is that any point inside the scanning helix belongs to one and only one PI-line. Unfortunately, he only provided a general formulation and did not describe the implementation details. To make this complicated algorithm more transparent, we report here specifically how to program the Katsevich algorithm in the planar detector geometry. As an important component, we also analyze the effects of various implementation parameters on the image quality. Our results are intended to be valuable for those who are interested in evaluating, improving and extending the Katsevich approach.