Investigation of the Kinematic System of a 450 kV CT Scanner and its Influence on Dimensional CT Metrology Applications

The accuracy of CT-based dimensional measurements remains yet largely uncertain, due to the high number of influencing factors related to the workpiece as well as the CT equipment, the measurement setup and subsequent data processing steps. [1] gives an overview of these unwanted effects which disturb the dimensional CT measurements. This paper focuses on the kinematic system of the CT scanner and the subsequent errors introduced by the imperfect positioning of this kinematic system. First, a kinematic model for a 450 kV CT scanner is presented. Next the geometrical error components (specified in ISO 230-1) and alignment errors between X-ray source, rotation table and detector have been determined. Finally a calibrated reference object and simulations have been used to show the influence of the geometrical errors and alignment errors on the dimensional measurements conducted using CT.

Publication year:2014