Beam-hardening corrections through a polychromatic projection model integrated to an iterative reconstruction algorithm

Trotta, Leonardo Di Schiavi; Matenine, Dmitri; Martini, Margherita; Stierstorfer, Karl; Lemaréchal, Yannick; Francus, Pierre; Després, Philippe

doi:10.1016/j.ndteint.2021.102594

Cited by 5 publications

(13 citation statements)

References 24 publications

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“…Second, the Itrax is used to measure the geochemistry at the surface of the sediment, whereas CT scanning is a 3D technique, so there will always be a mismatch between the analysed spots, entailing a difficult comparison. Moreover CT scan images can be affected by beam hardening, an artefact which affects the attenuation profile, creating high‐attenuation and low‐attenuation artefacts on the sample; it is caused by preferential attenuation of low energy photons biasing the reconstructed image quality mainly at the phase interfaces (Di Schiavi Trotta et al., 2022). In this case, beam hardening was relatively mild.…”

Section: Discussionmentioning

confidence: 99%

Exploring the application of dual‐energy CT to discriminate sediment facies in a varved sequence

Martini,

Francus,

Di Schiavi Trotta

et al. 2024

The Depositional Record

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Dual‐energy X‐ray computed tomography consists of imaging objects using two incident X‐ray beams of different energy to distinguish the different compounds within a sample based on their density (electron density, ρe) and elemental composition (effective atomic number, Zeff). The stoichiometric calibration for dual‐energy X‐ray computed tomography was already successfully implemented to identify single and homogeneous minerals easily and non‐destructively. It is here applied for the first time to a more complex and heterogeneous sample, a varved sediment core with three distinct facies. The output of dual‐energy X‐ray computed tomography was compared against elemental geochemistry obtained at the same resolution using a micro‐XRF core scanner. The three individual facies can be successfully differentiated using dual‐energy X‐ray computed tomography because their range of ρe and Zeff values allow their discrimination. Correlations with elemental geochemistry are also discussed but are less conclusive, probably because of variations in grain size and porosity, and because these high resolution analyses were not performed at the exact same location. The paper not only eventually discusses the limitations when using dual‐energy X‐ray computed tomography on sediments but also demonstrates its potential to quantitatively study sediment cores in a non‐destructive way.

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Section: Discussionmentioning

confidence: 99%

Exploring the application of dual‐energy CT to discriminate sediment facies in a varved sequence

Martini,

Francus,

Di Schiavi Trotta

et al. 2024

The Depositional Record

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“…where n is the reconstruction iteration number, ȳi is the estimated photon count, s is the index of the subset and S(s) is a well defined function that generates for each selected group of projections the subsets of rays Matenine (2011); Di Schiavi Trotta et al (2022). A high number of subsets is used to accelerate the reconstruction, whereas this value should be reduced at every iteration in order to decrease bias Beekman and Kamphuis (2001); Sidky et al (2006Sidky et al ( ).…”

Section: Osc-tvmentioning

confidence: 99%

“…The X-ray tube can be operated in the range of 70-140 kVp. This platform is used for several non-medical applications, including material characterization with dual-energy techniques Fortin et al (2013); Larmagnat et al (2019); Martini et al (2021); Di Schiavi Trotta et al (2022).…”

Section: Working With Proprietary Formatmentioning

confidence: 99%

Tomographic reconstruction strategies for nondestructive testing with a commercial CT scanner

Di Schiavi Trotta,

Matenine,

Lemaréchal

et al. 2023

Front. Earth Sci.

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In this work, a framework was developed to access and process raw data from a commercial X-ray Computed Tomography (CT) scanner for research purposes. Our method requires vendor-provided binaries to convert the data to a readable format and also to remove the effect of proprietary beam hardening preprocessing. As a result, custom reconstruction techniques, including beam-hardening corrections algorithms, can be applied. Small region-of-interest CT imaging techniques and different backprojection algorithms were investigated to improve image quality (spatial resolution, noise) with an in-house iterative reconstruction algorithm. For a reconstruction matrix of 512 pixels × 512 pixels, processing times of approximately 2.5 s per slice were obtained using a set of 8 x GPUs. With this framework, high-quality images of high density samples (e.g., minerals) can be obtained with reduced truncation-induced blurring, free of artifacts stemming from the reconstruction process and reduced beam-hardening artifacts.

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“…This platform is used for several nonmedical applications, including material characterization and custom beam hardening corrections with dualenergy techniques. 6,7 The process of using raw data from this medical CT scanner is illustrated in Fig. 1.…”

Section: Working With Proprietary Formatmentioning

confidence: 99%

“…These genuinely raw data (except for detector calibration), can thereafter be used in custom reconstruction algorithms designed to handle corrections from first principles, notably through dual-energy approaches. 7…”

Section: Working With Proprietary Formatmentioning

confidence: 99%

On the use of voxel-driven backprojection and iterative reconstruction for small ROI CT imaging

Trotta

Matenine²,

Martini³

et al. 2022

7th International Conference on Image Formation in X-Ray Computed Tomography

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In this work related to the use of a commercial medical CT scanner for the non-destructive analysis of highly attenuating materials (mineral samples), the effect of backprojection techniques and truncation artifacts corrections were explored. For small ROIs, the CT couch interferes significantly in images of small samples (few centimeters). An iterative reconstruction algorithm (OSC-TV) was used to perform reconstructions from uncorrected raw projection data made available through a collaboration with the CT vendor, who provided binaries and methods to remove low-level, proprietary data corrections (for beam hardening). The OSC-TV algorithm is customizable, allowing for the use of different forward-projection and backprojection techniques. Reconstruction parameters were tuned by performing simulations in a virtual phantom involving highly attenuating materials. Strategies to reconstruct small ROIs were also explored, with the objective of reducing truncation artifacts. Three samples were scanned to compare a ray-driven backprojection and a voxel-driven backprojection technique based on bilinear interpolation. The voxel-driven approach led to better results in terms of noise and reconstruction artifacts. An iterative ROI reconstruction technique was used to reconstruct small ROIs. This technique allows obtaining a sinogram with the projections of the ROI only. With that, truncation artifacts were reduced, which led to images with less blurring.

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Beam-hardening corrections through a polychromatic projection model integrated to an iterative reconstruction algorithm

Cited by 5 publications

References 24 publications

Exploring the application of dual‐energy CT to discriminate sediment facies in a varved sequence

Exploring the application of dual‐energy CT to discriminate sediment facies in a varved sequence

Tomographic reconstruction strategies for nondestructive testing with a commercial CT scanner

On the use of voxel-driven backprojection and iterative reconstruction for small ROI CT imaging

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