Limited view X-ray tomography for dimensional measurements

Abstract

6The growing use of complex and irregularly shaped components for safetycritical applications has increasingly led to the adoption of X-ray CT as an NDE inspection tool. Standard X-ray CT methods require thousands of projections, each regularly distributed evenly through 360• to produce an accurate image. The time consuming acquisition of thousands of projections can lead to significant bottlenecks. Recent developments in medical imaging driven by both increasing computational power and the desire to reduce patient X-ray exposure have led to the development of a number of limited view CT methodologies.Thus far these limited view algorithms have been applied to basic synthetic data derived from simple medical phantoms. Here, we use experimental data to rigorously test the capability of limited view algorithms to accurately reconstruct and precisely measure the dimensional features of an additive manufactured sample and a turbine blade. Our findings highlight the importance of prior information in producing accurate reconstructions capable of significantly reducing X-ray projections by at least an order of magnitude. In the turbine blade example a dramatic reduction in projections from 5000 to 24 was observed while still demonstrating the same level of accuracy as standard CT methods. The findings of the study also suggest the importance of sample complexity and the presence of sparsity in the X-ray projections in order to maximise the capabilities of these limited algorithms. With the ever increasing computational power limited view CT algorithms offer a method for reducing data acquisition time and alleviating manufacturing throughput bottlenecks without compromising

Complex artefact suppression for sparse reconstruction based on compensation approach in X‐ray computed tomography

“…where B is a blurring operator, D is a down-sampling operator, and 𝜁 serves as a noise term. There may be several matching high-resolution images X that fulfill the degradation model in Equation (5). Because the reconstruction problem is dramatically ill-posed, prior knowledge and sinogram compensation should be integrated into the reconstruction.…”

“…For CT reconstruction in inverse issues, the scanning environment, imaging geometry, and X-ray radiation dose are all crucial variables [3,4]. While it is limited to a few angles [5][6][7] either for faster sampling or for smaller exposure to radiation. Practically, the range of views that can be observed in a few observations is constrained due to physical restrictions on the acquisition method [8,9].…”

Three-dimensional subsurface defect shape reconstruction and visualisation by pulsed thermography

“…In the area of nuclear and aerospace industries, 3D visualisation is reconstructed from the digital X-ray images and has been used to view the location, shape and size of the defects like corrosion, delamination and crack, and evaluate the thickness of walls in the object of titanium aerospace investment casting [22,23]. However, the X-ray technology is comparatively time consuming [24], comes with potential health risks [25] to the user and is typically limited with respect to the maximum size of the parts to be analysed [22,[26][27][28][29].…”

Fast Tomographic Inspection of Cylindrical Objects

“…More recently, CT scanners are being used dedicated to metrology for dimensional quality control. High importance is given in this case to accuracy, traceability to the unit of length and measurement uncertainty [5][6][7]. New developments in CT technology, driven by research at synchrotron facilities and medical imaging, allow the technology to be applied in an automated production environment too [8,9].…”