Using Calibrated Samples for Uncertainty Analysis of X-Ray Computed Tomography

X-Ray computed tomography is the process of using a series of projections of an object at different rotations to create a fully digital 3D representation of its internal and external features. These projections are gained through the use of a radiation emitting source and a specialised crystal detector on either side of the subject. Used in both the medical and industrial sectors, this process has been proven extensively valuable in discovering defects without any damage to the scanned sample.However, due to the non-uniform nature of the X-Rays and the variance of the equipment used to collect these projections, the spatial dimensions of the final data cannot be guaranteed to match the true sizes. When using this method to analyse features less than 30 μm, it becomes increasingly important to gain confidence that the results are correct. By using a tungsten carbide sphere and bespoke designed phantoms measured with a modern coordinate measuring machine, an uncertainty budget has been produced in reference to ISO guides of measurement and system optimisation. Through referencing this data to further gained results on new samples, the methodology has been proven to be successful.