The CT (computed tomography) scanner has been used for many years now not only for medical measurements, but also in many industries, mostly for tasks such as defectoscopy, measuring sheet thickness, checking the joining of materials, but also for measuring the geometry of individual components. It is a good complement to coordinate contact and non-contact measurements for intra-structural measurements and inaccessible places. The variety of materials, however, makes it very difficult to select individual CT parameters. In this paper, a curve for selecting the maximum and minimum voltage of the lamp depending on the density of a given material has been determined and an interpolation polynomial (1d third-degree polynomial) has been used, by defining 3rd-degree glued functions (cubic spline) to determine intermediate voltage values to a given material density, so as to determine full data ranges. This approach will facilitate the work of selecting scanning parameters for nondestructive testing, as this is a difficult process and sometimes consumes half of the measurement time. Work is underway at the Accredited Coordinate Metrology Laboratory to develop a multi-criteria matrix for selecting CT measurement parameters for measurement accuracy.