X-ray-based computed tomography (CT) systems are increasingly used in industries such as aerospace, and medical devices, for non-destructive testing and for the evaluation of defects and inner structure. These industries require inspection resolutions at the nanometre scale and the overall aim of this project is to develop traceable measurement methods for determining the focal spot size, shape, and position of nanometre resolution X-ray tubes. The project will use these methods in the preparation of prenormative documents for submission to CEN TC 138 (Non-destructive testing) WG 1 (Radiographic testing) and to revise standards in the EN 12543 series for focal spot measurements as well as to harmonise standards and measurement methods between CEN, ISO, and ASTM.