The aim of this work was to obtain detection limits of computed tomography by mean of test geometries i.e. test phantoms and different filter materials. Depending on the material type, geometry and tomography parameters, detection limits were determined for computed tomography. The results of this work are aimed at the in the literature and CT practice only qualitatively known relation between parameter setting and image quality. Thereby a quantitative description to improve further investigation of computed tomography is obtained. Several test runs with test phantoms made of aluminium and iron define the maximum transmissive thickness and limits of the resolution contrast. In addition the influence of different filter materials and filter thicknesses were investigated.