![]() ![]() Using a linear reconstruction method such as the filtered back projection (FBP), which assumes that the object attenuates the X-ray linearly with the path length, results in cupping and streak artifacts which degrade the quality of the reconstructed image. This results in a non-linearity between the attenuation of the beam and the length of the propagation path. Since the attenuation value of the material is energy-dependent, it decreases as the beam is hardened. This shifts the mean of the spectrum to a higher value and results in the hardening of the beam. When photons of different energies penetrate through the object, low-energy photons are more easily absorbed than high-energy photons. One of the major artifacts that influence image quality is the BH artifact, which results from the polychromatic nature of the X-ray source. However, CT usually suffers from undesirable artifacts such as scattering, and beam hardening (BH) due to the physical nature of the X-rays. It is shown that the proposed method results in images with improved contrast-to-noise ratio (CNR) in comparison to the images corrected from only the scatter artifacts and the BH-corrected images using the state-of-the-art empirical BH correction method.Ĭomputed tomography (CT) is an imaging technique that has been widely applied in medical and industrial applications such as for medical diagnosis and non-destructive testing. To evaluate the proposed BH correction method, we have conducted extensive experiments on real-world CT data. The simulated projections in this work are performed using a multi-GPU-accelerated forward projection model which ensures a fast BH correction in near real-time. As a result, an accurate non-linearity correction term is derived that leads to an accurate BH correction result. The estimated polychromatic projection is accurately derived using the least square estimation (LSE) method by minimizing the difference between the experimental projection and the linear combination of simulated polychromatic projections. Then, the non-linearity effect of the BH is corrected by adding the difference between the estimated monochromatic and the polychromatic simulated projections of the segmented image. This is achieved by performing a wide sweep of the material based on an experimentally measured look-up table to obtain the closest estimate of the material. This work aims to propose a fast and accurate BH correction method that requires no prior knowledge of the materials and corrects first and higher-order BH artifacts. This BH artifact arises due to the polychromatic nature of the X-ray source and causes cupping and streak artifacts. Beam hardening (BH) is one of the major artifacts that severely reduces the quality of computed tomography (CT) imaging. ![]()
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