Glossary term
X-Ray Computed Tomography
A volumetric imaging method that reconstructs internal structure from many X-ray projection measurements.
Definition
methodX-ray computed tomography is a non-destructive imaging method that reconstructs a three-dimensional volume from X-ray projections taken around a specimen.
Industrial X-ray CT converts attenuation measurements into a voxel-based representation of internal and external geometry. Engineers use it to inspect porosity, cracks, inclusions, wall thickness, assemblies, additive-manufactured parts, composite layups, welds, and metrology features without sectioning the part.
X-ray computed tomography builds a three-dimensional image from many two-dimensional X-ray projections. As the specimen rotates, the detector records how much radiation is attenuated along different paths. Reconstruction algorithms convert those projections into a voxel volume that estimates local X-ray attenuation.
The resulting CT data can reveal hidden geometry, pores, cracks, inclusions, fiber orientation, lack of fusion, wall-thickness variation, assembled interfaces, and internal defects. Engineers may also segment the volume to measure dimensions, calculate void fraction, generate finite-element meshes, or compare an as-manufactured part with its CAD model.
Engineering use
Industrial CT is valuable when destructive sectioning would damage the part or miss three-dimensional defect networks. It is common in additive manufacturing, castings, composites, electronics packaging, weld qualification, medical-device development, archaeology, and failure analysis.
Resolution is governed by source spot size, detector pixel size, magnification, specimen size, material attenuation, exposure time, reconstruction settings, and mechanical stability. A small specimen can often be imaged at finer voxel size than a large dense component. Voxel size is not automatically equal to true spatial resolution, because contrast, noise, edge response, reconstruction blur, and segmentation method also matter.
Common mistakes
A common mistake is treating a CT image as an exact solid model. Beam hardening, scatter, ring artefacts, motion, partial-volume effects, metal streaks, and threshold choice can distort dimensions and defect size. Another mistake is comparing CT measurements without stating calibration, voxel size, reconstruction parameters, segmentation rules, and uncertainty. A strong CT inspection plan states the material, inspected feature size, required detectability, scan geometry, artefact controls, reference standards, and validation evidence.