CAD-BASED SCATTER COMPENSATION FOR POLYCHROMATIC RECONSTRUCTION OF ADDITIVE MANUFACTURED PARTS

Abstract

High density materials, such as metals, strongly scatter Xray photons during X-ray Computed Tomography (CT) scans, which is detrimental to the quality of the reconstructed images. In this study, a scatter compensation method for X-ray CT, based on Monte-Carlo (MC) simulations from the object's CAD model, is presented and employed in conjunction with polychromatic reconstructions. The estimation of the scatter contributions is accelerated by 1) reducing the number of simulated projections accordingly to the Nyquist theorem, 2) noise reduction 3) angular interpolation. The method was applied to enhance CT images of a steel object produced via Additive Manufacturing, whose CAD model is known. Results show that, in conjunction with polychromatic reconstruction, our method can efficiently reduce beam hardening, scattering artifacts and increase the contrast of defects within the object.