title: A post-scan method for correcting artefacts of slow geometry changes during micro-tomographic scans.
abstract: Micro-CT imaging of objects at very high magnification runs into the problem of small geometric movements of the x-ray emission spot relative to the object, thermally induced or otherwise, causing magnified shifts in the projection images during scanning. This produces movement artefacts in the reconstructed images. Here a technique is described to correct such movements by adding a short reference scan at the end of a high magnification scan, with a very large rotation step. Where geometry changes during a scan are slow, such movements can be considered minimal during this very short "post-scan". Registration of the post-scan images with corresponding images in the main scan allow X/Y pixel shifts in the projection images associated with the geometry movement to be calculated, and corrected during reconstruction. This post-scan correction method was applied here to scans of three small objects, all with a voxel size less than one micron, in a desktop micro-CT and a nano-CT scanner. The method substantially reduced movement artefacts from the reconstructed images, improving image quality and resolution. Where the geometry movement results largely from thermal movement of the x-ray micro-focus emission spot, the post-scan method allows the reconstruction of the spatio-temporal trajectory of this spot movement.
authors.affiliation: SkyScan N.V., Kartuizersweg 3B, Kontich, Belgium. phil.salmon@skyscan.be
authors.forename: P L
authors.initials: PL
authors.lastname: Salmon
authors.forename: X
authors.initials: X
authors.lastname: Liu
authors.forename: A
authors.initials: A
authors.lastname: Sasov
mesh_terms: D000538:Aluminum Silicates; D000818:Animals; D016477:Artifacts; D000077215:Clay; D005360:Fibula / Q000000981:diagnostic imaging; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D051379:Mice; D009038:Motion; D012399:Rotation; D014934:Wood; D055114:X-Ray Microtomography / Q000379:methods*
chemical_list: D000538:Aluminum Silicates; D000077215:Clay