Evaluation of A Micro CT Scan System Based on Digital Image Correlation Profile of Multiple Radiographs

Abstract

X-ray computed tomography system is a non-destructive testing tool which can visualize the internal structure of an object. However, the reconstruction image result can be disturbed by artefacts. The center of rotation position is a factor that needs to be controlled to avoid artefact. That is why a method to evaluate the performance of CT system is needed. The method is developed using x-ray micro-CT system and evaluated based on Digital Image Correlation. DIC measurement is based on tracking correlation function of a group of pixel which have a unique grey value from the test images and a reference image. The DIC value of multiple radiographs and the reference radiograph are calculated and then plotted by the angle of rotation to get the DIC profile value. The multiple radiographs are obtained from scanning object by simulation and experiment using CT Simulator software and x-ray Micro-CT system at Fisika Atom dan Inti FMIPA UGM laboratory. The results show that the ideal DIC profile value of radiograph image from simulation is a constant straight line for every size variation of the object. However, from the experiment, the result show deviation toward –y for every size variation of the object that indicate the shift of COR position in micro-CT system. The result also similar using center of mass profile value as comparison.