Geometry Calibration of a Modular Stereo Cone-Beam X-ray CT System

Nguyen, Van; Sanctorum, Joaquim G.; Wassenbergh, Sam Van; Dirckx, Joris J.J.; Sijbers, Jan; Beenhouwer, Jan De

doi:10.3390/jimaging7030054

Cited by 10 publications

(13 citation statements)

References 25 publications

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“…The distances from the X-ray source (SRD) and the detector (DRD) to the axis of rotation were 1025 mm and 278 mm, respectively. As the set-up is highly modular, the geometry of the set-up was calibrated using a phantom-based method 8,9 . Prior to geometry calibration and reconstruction, the geometric distortion in the projections induced by the Xray image intensifier was corrected using a method based on digital image correlation 10,11 .…”

Section: Image Acquisitionmentioning

confidence: 99%

Assessment of perceptual quality measures for multi-exposure radiography and tomography

Sanctorum

Jeught²,

Wassenbergh³

et al. 2022

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

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Fusion of X-ray projection images obtained with different exposure levels is a promising technique for studying objects with features beyond the dynamic range of the X-ray detector. Various multi-exposure fusion techniques are described in the literature, yet a direct comparison between these methods is not available. This was mainly due to the absence of objective quality measures dedicated to multi-exposure X-ray images and tomographic reconstructions, a problem remaining unsolved to this day. Therefore, in this work, we compare several fusion algorithms in terms of perceptual quality using recently reported quality measures based on structural similarity. Moreover, we investigate whether these quality measures apply to tomographic slices as well. Our results indicate that the reliability of the quality measures is more convincing for fused projection images as opposed to reconstructed slices. Additionally, it is shown that fusion algorithms developed for optical photography are also suitable for multi-exposure X-ray image fusion to increase perceptual quality.

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Section: Image Acquisitionmentioning

confidence: 99%

Assessment of perceptual quality measures for multi-exposure radiography and tomography

Sanctorum

Jeught²,

Wassenbergh³

et al. 2022

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

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“…To rotate the samples, a custom-made rotation stage was used. A frequency-controlled asynchronous motor, equipped with a factor 40 gearbox, allows the top platform to make a complete revolution in ~2 s, during which the projection data is continuously recorded with a shutter time of 0.5 ms. As the 3D²YMOX system is highly modular (all components can be translated and rotated independently), there is a continuous range of possible detector offset, but every modification of the set-up requires a calibration of the system's geometry, for which a method developed by Nguyen et al was applied (Nguyen et al 2021). Since the images are recorded using XRIIs, geometric distortion is present in every frame, deteriorating the accuracy of the geometry calibration and the quality of the tomographic reconstruction.…”

Section: Image Acquisitionmentioning

confidence: 99%

Extended imaging volume in cone-beam x-ray tomography using the weighted simultaneous iterative reconstruction technique

Sanctorum¹,

Wassenbergh²,

Nguyen³

et al. 2021

Phys. Med. Biol.

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An issue in computerized X-ray tomography is the limited size of available detectors relative to objects of interest. A solution was provided in the past two decades by positioning the detector in a lateral offset position, increasing the effective field of view (FOV) and thus the diameter of the reconstructed volume. However, this introduced artifacts in the obtained reconstructions, caused by projection truncation and data redundancy. These issues can be addressed by incorporating an additional data weighting step in the reconstruction algorithms, known as redundancy weighting. In this work, we present an implementation of redundancy weighting in the widely-used Simultaneous Iterative Reconstruction Technique (SIRT), yielding the W-SIRT method. The new technique is validated using geometric phantoms and a rabbit specimen, by performing both simulation studies as well as physical experiments. The experiments are carried out in a highly flexible stereoscopic X-ray system equipped with X-ray image intensifiers (XRIIs). The simulations showed that higher values of CNR could be obtained using the W-SIRT approach as compared to a weighted implementation of SART. The convergence rate of the W-SIRT was accelerated by including a relaxation parameter in the W-SIRT algorithm, creating the aW-SIRT algorithm. This allowed to obtain the same results as the W-SIRT algorithm, but at half the number of iterations, yielding a much shorter computation time. The aW-SIRT algorithm has proven to perform well for both large as well as small regions of overlap, outperforming the pre-convolutional Feldkamp-David-Kress (FDK) algorithm for small overlap regions (or large detector offsets). The experiments confirmed the results of the simulations. Using the aW-SIRT algorithm, the effective FOV was increased by >75%, only limited by experimental constraints. Although an XRII is used in this work, the method readily applies to flat-panel detectors as well.

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“…During a full rotation, the device generates thousands of images in high grayscale (e.g., the GE Phoenix v|tomex|m uses 14 bit). The most common is the implementation of complex algorithms at the reconstruction stage, resulting in correction of images such as beam hardening correction, automatic geometry calibration, and geometry optimization [ 23 , 24 ]. The reconstructed object can be visually inspected by analyzing 2D cross-sectional images, 3D images, and further volumetric analysis.…”

Section: Introductionmentioning

confidence: 99%

Application of X-ray Computed Tomography to Verify Bond Failures Mechanism of Fiber-Reinforced Fine-Grain Concrete

et al. 2022

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This paper proposes the use of X-ray computed tomography (µCT, xCT) measurements together with finite element method (FEM) numerical modelling to assess bond failures mechanism of fiber-reinforced fine-grain concrete. Fiber-reinforced concrete is becoming popular for application in civil engineering structures. A dynamically developing topic related to concretes is the determination of bond characteristics. Nowadays, modern technologies allow inspecting the inside of the element without the need to damage its structure. This paper discusses the application of computed tomography in order to identify damage occurring in the structure of fiber-reinforced fine-grain concrete during bond failure tests. The publication is part of a larger study to determine the bonding properties of Ukrainian steel fibers in fine-grain concrete. The authors focused on the visual evaluation of sections obtained from tomographic data. Separately, the results of volumetric analysis were presented to quantitatively assess the changes occurring in the matrix structure. Finite element analysis is an addition to the substantive part and allows us to compare real damage areas with theoretical stress concentration areas. The result of the work is the identification of a path that allows verification of the locations where matrix destruction occurs.

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Geometry Calibration of a Modular Stereo Cone-Beam X-ray CT System

Cited by 10 publications

References 25 publications

Assessment of perceptual quality measures for multi-exposure radiography and tomography

Assessment of perceptual quality measures for multi-exposure radiography and tomography

Extended imaging volume in cone-beam x-ray tomography using the weighted simultaneous iterative reconstruction technique

Application of X-ray Computed Tomography to Verify Bond Failures Mechanism of Fiber-Reinforced Fine-Grain Concrete

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