A filter model to analyze reconstruction artifacts in perfusion C-arm CT

Interventional perfusion imaging with a C-arm angiography system capable of 3-D imaging (C-arm CT) could optimize the clinical workflow during stroke treatment. Acquisition times are currently of the order of several seconds per short-scan and filtered backprojection reconstruction artifacts can arise due to the time-dependence of the attenuation values. In this paper, we present a novel formalism to model reconstruction artifacts by a spatio-temporal filter in the object domain. The filter consists of terms that depend on the temporal derivatives of the attenuation values. Using this model, artifacts due to time-dependent attenuation values can be well explained and studied. We apply the filter model to analyze redundancy weighting schemes in order to reduce these artifacts. Furthermore, this model could be the basis to develop new dynamic reconstruction algorithms.