DIRECTT reconstructions compared to filtered back projections

Based on measurements and on model calculations tomographic reconstructions by DIRECTT (direct iterative reconstruction of computed tomography trajectories) are evaluated in comparison to filtered back projection. This is established by modified circular Modulation Transfer Functions (MTF) and by integral parameters in Radon and real space. The reconstructions of the experimental data refer to measurements of simple shapes under well defined physical conditions such as monochromatic radiation, suppression of refractive edge artifacts and radiometric intensity measurement. The quality of DIRECTT reconstructions does not primarily depend on the type of filters applied nor their abandonment, which differs essentially from the performance of the filtered back projection.