Stabilizing dual-energy x-ray computed tomography reconstructions using patch-based regularization

Abstract

Recent years have seen growing interest in exploiting dual-and multi-energy measurements in computed tomography (CT) in order to characterize material properties as well as object shape. Materials characterization is performed by decomposing the scene into constitutive basis functions, such as Compton scatter and photoelectric absorption functions. While well motivated physically, the joint recovery of the spatial distribution of photoelectric and Compton properties is severely complicated by the fact that the data are several orders of magnitude more sensitive to Compton scatter coefficients than to photoelectric absorption, so small errors in Compton estimates can create large artifacts in the photoelectric estimate. To address these issues, we propose a model-based iterative approach which uses patch-based regularization terms to stabilize inversion of photoelectric coefficients, and solve the resulting problem though use of computationally attractive Alternating Direction Method of Multipliers (ADMM) solution techniques. Using simulations and experimental data acquired on a commercial scanner, we demonstrate that the proposed processing can lead to more stable material property estimates which should aid materials characterization in future dual-and multi-energy CT systems.

Imaging based on Compton scattering: model-uncertainty and data-driven reconstruction methods

“…Currently the energy is exploited in multi-spectral CT as a supplementary variable split into several channels delivering a precious information on the attenuation coefficient at different energy levels. We refer to [4,34,15,42,28,19,18]. However the recently achieved energy resolution, more precisely the FWHM, of the current scintillation crystals opens the way to consider the energy as a reliable dimension along with viewpoints and detector positions.…”

Reconstruction algorithm for 3D Compton scattering imaging with incomplete data

“…One can mention Single Photon Emission CT, Positron Emission Tomography or Cone-Beam CT for the standard 3D imaging systems based on an ionizing source. In these configurations, the energy discrimination has very limited use but the idea of exploiting it in order to enhance the image quality, optimize the acquisition processor to compensate for some limitations (such as limited angle issues) has led to various works [1][2][3][4][5][6][7][8]. However, the energy has been used to provide additional information in these imaging modalities (e.g.…”

A joint reconstruction and lambda tomography regularization technique for energy-resolved X-ray imaging

“…The literature considers joint image reconstruction and regularization in for example, [1,19,40,46,47,6,50,12,20,11,48,10,45,4]. See also the special issue [3] for a more general review of joint reconstruction techniques.…”