Validation of a Method for the Optimization of Scan Parameters for Measuring with Computed Tomogography

Abstract

When measuring with computed tomography, the measurement uncertainty of measured values is strongly influenced by the geometry and material of the measured object as well as by the chosen scan parameters, such as those of the X-ray source and detector. Optimizing the scan parameters to achieve a sufficiently high measurement precision while keeping the measurement time as short as possible, is crucial for the efficient use of a coordinate measuring machine. Few tools are available to aid the user at the moment. Therefore scan parameters are often set based on purely empirical studies or subjective assessments of X-ray images and thus on the basis of personal experience. A new method for the automatic determination of scan parameters for a given measurement time or a given measurement precision of a single measurement point, as well as a given minimum necessary structural resolution has been developed. It is based on a method for simulating the measurement precision of surface points that are relevant for the measurement task. In this work, values for scan parameters to maintain the highest possible single point precision for a given measurement time and minimum necessary structural resolution have been determined for a multi-sphere standard using the newly developed setting algorithm and by evaluating empirical studies. The results of both methods are presented and compared.