Validation of a novel microradiography device for characterization of bone mineralization

International audienceIn order to simplify bone mineralization measurements, a system using radiographic films has been updated with a digital detector. The objective of this paper was to validate this new device. Technologies and physical phenomena involved in both systems (radiographic films and digital detector) are different. The methodology used to compare the two systems was based on image quality and assessed on two main parameters: contrast to noise ratio and spatial resolution. Results showed that the contrast to noise ratio was similar between the two systems, provided that acquisition parameters were optimized. With regard to spatial resolution, a magnification factor of at least 4 or more was required to achieve the same resolution as films. A final validation was also shown on a real image of a bone sample. The results showed that both systems have similar image quality performances, and the system using digital detector has several advantages (easier to use than films, no consumables and faster acquisition time)

A multi-resolution image reconstruction method in X-ray computed tomography

International audienceWe propose a multiresolution X-ray imaging method designed for non-destructive testing/ evaluation (NDT/NDE) applications which can also be used for small animal imaging studies. Two sets of projections taken at different magnifications are combined and a multiresolution image is reconstructed. A geometrical relation is introduced in order to combine properly the two sets of data and the processing using wavelet transforms is described. The accuracy of the reconstruction procedure is verified through a comparison to the standard filtered backprojection (FBP) algorithm on simulated data

Image Fusion Based on Evidence Theory for Multi-Energy X-Ray Computed Tomography

International audienc

Projet de physique: 2ème année ASINSA

National audienc

Exploration des dimensions d’une expérience scientifique : le projet de physique en ASINSA.: Enjeux d’une approche multi-dimensionnelle du projet de physique en ASINSA

National audienc

X-ray Computed Tomography Reconstruction on Non-Standard Trajectories for Robotized Inspection

International audienceThe inspection of complex industrial parts with X-ray computedtomography (CT) is of great interest to characterize them and detect potential flaws.Classically CT acquisition is based on a circular trajectory and this is by far the mostfrequent case in industrial applications. The use of robotic arms for inspection isrecent and it is mainly done for accessing specific and difficult views in digitalradiographic inspection. A new X-ray inspection platform is being installed at CEALIST, which uses two robotic arms for positioning the X-ray source and thedetector. In parallel to the development of this platform which enables a largevariety of scanning trajectories, work will focus on developing CT reconstructionalgorithms that are adapted to non-standard trajectories. We present here newchallenges brought by these robotized inspections and preliminary results forreconstruction on such trajectories. CIVA software is used to simulate thesecomplex inspections and our developed methods will be integrated as reconstructiontools

A spectral X-ray CT simulation study for quantitative determination of iron

International audienceIron is an essential element in the human body and disorders in iron such as iron deficiency or overload can cause serious diseases. This paper aims to explore the ability of spectral X-ray CT to quantitatively separate iron from calcium and potassium and to investigate the influence of different acquisition parameters on material decomposition performance. We simulated spectral X-ray CT imaging of a PMMA phantom filled with iron, calcium, and potassium solutions at various concentrations (15–200 mg/cc). Different acquisition parameters were considered, such as the number of energy bins (6, 10, 15, 20, 30, 60) and exposure factor per projection (0.025, 0.1, 1, 10, 100 mA s). Based on the simulation data, we investigated the performance of two regularized material decomposition approaches: projection domain method and image domain method. It was found that the former method discriminated iron from calcium, potassium and water in all cases and tended to benefit from lower number of energy bins for lower exposure factor acquisition. The latter method succeeded in iron determination only when the number of energy bins equals 60, and in this case, the contrast-to-noise ratios of the decomposed iron images are higher than those obtained using the projection domain method. The results demonstrate that both methods are able to discriminate and quantify iron from calcium, potassium and water under certain conditions. Their performances vary with the acquisition parameters of spectral CT. One can use one method or the other to benefit better performance according to the data available

Automated segmentation of ultrasonic volumetricdata of composite materials

International audienceManual ultrasonic testing is frequently applied to inspect the quality of carbon fibre-reinforced polymer composites(CFRP), especially in the aerospace industry. There is an immediate requirement to replace manual ultrasonic testing anddata evaluation with an automated system. A part of the solution is provided via automated acquisition of ultrasounddata. The second part to be solved is the analysis of the enormous amount of data generated. The objective of thiscontribution is to propose a method that can provide an automated interpretation of data. The proposed method istested on two CFRP samples with artificial defects of different sizes, depths and shapes

Implementation and Evaluation of Two Helical CTReconstruction Algorithms in CIVA

International audienceThe large majority of industrial CT systems reconstruct the 3D volume by using an acquisition on a circular trajectory.However, when inspecting long objects which are highly anisotropic, this scanning geometry creates severe artifacts in thereconstruction. For this reason, the use of an advanced CT scanning method like helical data acquisition is an ecient way toaddress this aspect known as the long-object problem. Recently, several analytically exact and quasi-exact inversion formulas forhelical cone-beam reconstruction have been proposed. Among them, we identified two algorithms of interest for our case. Thesealgorithms are exact and of filtered back-projection structure. In this work we implemented the filtered-backprojection (FBP) andbackprojection-filtration (BPF) algorithms of Zou and Pan (2004). For performance evaluation, we present a numerical comparisonof the two selected algorithms with the helical FDK algorithm using both complete (noiseless and noisy) and truncated datagenerated by CIVA (the simulation platform for non-destructive testing techniques developed at CEA)