Journal of Imaging

Editorial

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3 pages, 188 KiB

Open AccessEditorial

X-ray Digital Radiography and Computed Tomography

by Maria Pia Morigi and Fauzia Albertin

J. Imaging 2022, 8(5), 119; https://doi.org/10.3390/jimaging8050119 - 21 Apr 2022

Cited by 6 | Viewed by 4156

Abstract

In recent years, X-ray imaging has rapidly grown and spread beyond the medical field; today, it plays a key role in diverse research areas [...] Full article

(This article belongs to the Special Issue X-ray Digital Radiography and Computed Tomography)

Research

Jump to: Editorial, Review

25 pages, 8635 KiB

Open AccessArticle

X-ray Tomography Unveils the Construction Technique of Un-Montu’s Egyptian Coffin (Early 26th Dynasty)

by Fauzia Albertin, Maria Pia Morigi, Matteo Bettuzzi, Rosa Brancaccio, Nicola Macchioni, Roberto Saccuman, Gianluca Quarta, Lucio Calcagnile and Daniela Picchi

J. Imaging 2022, 8(2), 39; https://doi.org/10.3390/jimaging8020039 - 7 Feb 2022

Cited by 6 | Viewed by 5190

Abstract

The Bologna Archaeological Museum, in cooperation with prestigious Italian universities, institutions, and independent scholars, recently began a vast investigation programme on a group of Egyptian coffins of Theban provenance dating to the first millennium BC, primarily the 25th–26th Dynasty (c. 746–525 BC). [...] Read more.

The Bologna Archaeological Museum, in cooperation with prestigious Italian universities, institutions, and independent scholars, recently began a vast investigation programme on a group of Egyptian coffins of Theban provenance dating to the first millennium BC, primarily the 25th–26th Dynasty (c. 746–525 BC). Herein, we present the results of the multidisciplinary investigation carried out on one of these coffins before its restoration intervention: the anthropoid wooden coffin of Un-Montu (Inv. MCABo EG1960). The integration of radiocarbon dating, wood species identification, and CT imaging enabled a deep understanding of the coffin’s wooden structure. In particular, we discuss the results of the tomographic investigation performed in situ. The use of a transportable X-ray facility largely reduced the risks associated with the transfer of the large object (1.80 cm tall) out of the museum without compromising image quality. Thanks to the 3D tomographic imaging, the coffin revealed the secrets of its construction technique, from the rational use of wood to the employment of canvas (incamottatura), from the use of dowels to the assembly procedure. Full article

(This article belongs to the Special Issue X-ray Digital Radiography and Computed Tomography)

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9 pages, 7698 KiB

Open AccessArticle

Robust Image Reconstruction Strategy for Multiscalar Holotomography

by Maximilian Ullherr, Matthias Diez and Simon Zabler

J. Imaging 2022, 8(2), 37; https://doi.org/10.3390/jimaging8020037 - 2 Feb 2022

Cited by 2 | Viewed by 2468

Abstract

Holotomography is an extension of computed tomography where samples with low X-ray absorption can be investigated with higher contrast. In order to achieve this, the imaging system must yield an optical resolution of a few micrometers or less, which reduces the measurement area [...] Read more.

Holotomography is an extension of computed tomography where samples with low X-ray absorption can be investigated with higher contrast. In order to achieve this, the imaging system must yield an optical resolution of a few micrometers or less, which reduces the measurement area (field of view = FOV) to a few mm at most. If the sample size, however, exceeds the field of view (called local tomography or region of interest = ROI CT), filter problems arise during the CT reconstruction and phase retrieval in holotomography. In this paper, we will first investigate the practical impact of these filter problems and discuss approximate solutions. Secondly, we will investigate the effectiveness of a technique we call “multiscalar holotomography”, where, in addition to the ROI CT, a lower resolution non-ROI CT measurement is recorded. This is used to avoid the filter problems while simultaneously reconstructing a larger part of the sample, albeit with a lower resolution in the additional area. Full article

(This article belongs to the Special Issue X-ray Digital Radiography and Computed Tomography)

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11 pages, 3563 KiB

Open AccessArticle

A Priori Information Based Time-Resolved 3D Analysis of the Trajectory and Spatial Orientation of Fast-Moving Objects Using High-Speed Flash X-ray Imaging

by Ralph Langkemper, Stefan Moser, Markus Büttner, Dominik Rakus, Axel Sättler and Siegfried Nau

J. Imaging 2022, 8(2), 28; https://doi.org/10.3390/jimaging8020028 - 28 Jan 2022

Cited by 1 | Viewed by 2650

Abstract

This paper shows that the X-ray analysis method known from the medical field, using a priori information, can provide a lot more information than the common analysis for high-speed experiments. Via spatial registration of known 3D shapes with the help of 2D X-ray [...] Read more.

This paper shows that the X-ray analysis method known from the medical field, using a priori information, can provide a lot more information than the common analysis for high-speed experiments. Via spatial registration of known 3D shapes with the help of 2D X-ray images, it is possible to derive the spatial position and orientation of the examined parts. The method was demonstrated on the example of the sabot discard of a subcaliber projectile. The velocity of the examined object amounts up to 1600 m/s. As a priori information, the geometry of the experimental setup and the shape of the projectile and sabot parts were used. The setup includes four different positions or points in time to examine the behavior over time. It was possible to place the parts within a spatial accuracy of 0.85 mm (standard deviation), respectively 1.7 mm for 95% of the errors within this range. The error is mainly influenced by the accuracy of the experimental setup and the tagging of the feature points on the X-ray images. Full article

(This article belongs to the Special Issue X-ray Digital Radiography and Computed Tomography)

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22 pages, 7321 KiB

Open AccessArticle

Principles for an Implementation of a Complete CT Reconstruction Tool Chain for Arbitrary Sized Data Sets and Its GPU Optimization

by Jürgen Hofmann, Alexander Flisch and Robert Zboray

J. Imaging 2022, 8(1), 12; https://doi.org/10.3390/jimaging8010012 - 15 Jan 2022

Cited by 3 | Viewed by 3143

Abstract

This article describes the implementation of an efficient and fast in-house computed tomography (CT) reconstruction framework. The implementation principles of this cone-beam CT reconstruction tool chain are described here. The article mainly covers the core part of CT reconstruction, the filtered backprojection and [...] Read more.

This article describes the implementation of an efficient and fast in-house computed tomography (CT) reconstruction framework. The implementation principles of this cone-beam CT reconstruction tool chain are described here. The article mainly covers the core part of CT reconstruction, the filtered backprojection and its speed up on GPU hardware. Methods and implementations of tools for artifact reduction such as ring artifacts, beam hardening, algorithms for the center of rotation determination and tilted rotation axis correction are presented. The framework allows the reconstruction of CT images of arbitrary data size. Strategies on data splitting and GPU kernel optimization techniques applied for the backprojection process are illustrated by a few examples. Full article

(This article belongs to the Special Issue X-ray Digital Radiography and Computed Tomography)

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16 pages, 5518 KiB

Open AccessArticle

Micro- and Nano-Scales Three-Dimensional Characterisation of Softwood

by Alessandra Patera, Anne Bonnin and Rajmund Mokso

J. Imaging 2021, 7(12), 263; https://doi.org/10.3390/jimaging7120263 - 3 Dec 2021

Cited by 7 | Viewed by 2623

Abstract

Understanding the mechanical response of cellular biological materials to environmental stimuli is of fundamental importance from an engineering perspective in composites. To provide a deep understanding of their behaviour, an exhaustive analytical and experimental protocol is required. Attention is focused on softwood but [...] Read more.

Understanding the mechanical response of cellular biological materials to environmental stimuli is of fundamental importance from an engineering perspective in composites. To provide a deep understanding of their behaviour, an exhaustive analytical and experimental protocol is required. Attention is focused on softwood but the approach can be applied to a range of cellular materials. This work presents a new non-invasive multi-scale approach for the investigation of the hygro-mechanical behaviour of softwood. At the TOMCAT beamline of the Paul Scherrer Institute, in Switzerland, the swelling behaviour of softwood was probed at the cellular and sub-cellular scales by means of 3D high-resolution phase-contrast X-ray imaging. At the cellular scale, new findings in the anisotropic and reversible swelling behaviour of softwood and in the origin of swelling hysteresis of porous materials are explained from a mechanical perspective. However, the mechanical and moisture properties of wood highly depend on sub-cellular features of the wood cell wall, such as bordered pits, yielding local deformations during a full hygroscopic loading protocol. Full article

(This article belongs to the Special Issue X-ray Digital Radiography and Computed Tomography)

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10 pages, 1766 KiB

Open AccessArticle

Copper and Trace Elements in Gallbladder form Patients with Wilson’s Disease Imaged and Determined by Synchrotron X-ray Fluorescence

by Wolf Osterode, Gerald Falkenberg and Fritz Wrba

J. Imaging 2021, 7(12), 261; https://doi.org/10.3390/jimaging7120261 - 3 Dec 2021

Cited by 4 | Viewed by 2783

Abstract

Investigations about suspected tissue alterations and the role of gallbladder in Wilson’s disease (WD)—an inherited genetic disease with impaired copper metabolism—are rare. Therefore, tissue from patients with genetically characterised WD was investigated by microscopic synchrotron X-ray fluorescence (µSRXRF). For two-dimensional imaging and quantification [...] Read more.

Investigations about suspected tissue alterations and the role of gallbladder in Wilson’s disease (WD)—an inherited genetic disease with impaired copper metabolism—are rare. Therefore, tissue from patients with genetically characterised WD was investigated by microscopic synchrotron X-ray fluorescence (µSRXRF). For two-dimensional imaging and quantification of elements, X-ray spectra were peak-fitted, and the net peak intensities were normalised to the intensity of the incoming monochromatic beam intensity. Concentrations were calculated by fundamental parameter-based program quant and external standardisation. Copper (Cu), zinc (Zn) and iron (Fe) along with sulphur (S) and phosphorus (P) mappings could be demonstrated in a near histological resolution. All these elements were increased compared to gallbladder tissue from controls. Cu and Zn and Fe in WD-GB were mostly found to be enhanced in the epithelium. We documented a significant linear relationship with Cu, Zn and sulphur. Concentrations of Cu/Zn were roughly 1:1 while S/Cu was about 100:1, depending on the selected areas for investigation. The significant linear relationship with Cu, Zn and sulphur let us assume that metallothioneins, which are sulphur-rich proteins, are increased too. Our data let us suggest that the WD gallbladder is the first in the gastrointestinal tract to reabsorb metals to prevent oxidative damage caused by metal toxicity. Full article

(This article belongs to the Special Issue X-ray Digital Radiography and Computed Tomography)

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9 pages, 32789 KiB

Open AccessArticle

High-Resolution Scanning Coded-Mask-Based X-ray Multi-Contrast Imaging and Tomography

by Zhi Qiao, Xianbo Shi, Michael Wojcik and Lahsen Assoufid

J. Imaging 2021, 7(12), 249; https://doi.org/10.3390/jimaging7120249 - 24 Nov 2021

Cited by 6 | Viewed by 2740

Abstract

Near-field X-ray speckle tracking has been used in phase-contrast imaging and tomography as an emerging technique, providing higher contrast images than traditional absorption radiography. Most reported methods use sandpaper or membrane filters as speckle generators and digital image cross-correlation for phase reconstruction, which [...] Read more.

Near-field X-ray speckle tracking has been used in phase-contrast imaging and tomography as an emerging technique, providing higher contrast images than traditional absorption radiography. Most reported methods use sandpaper or membrane filters as speckle generators and digital image cross-correlation for phase reconstruction, which has either limited resolution or requires a large number of position scanning steps. Recently, we have proposed a novel coded-mask-based multi-contrast imaging (CMMI) technique for single-shot measurement with superior performance in efficiency and resolution compared with other single-shot methods. We present here a scanning CMMI method for the ultimate imaging resolution and phase sensitivity by using a coded mask as a high-contrast speckle generator, the flexible scanning mode, the adaption of advanced maximum-likelihood optimization to scanning data, and the multi-resolution analysis. Scanning CMMI can outperform other speckle-based imaging methods, such as X-ray speckle vector tracking, providing higher quality absorption, phase, and dark-field images with fewer scanning steps. Scanning CMMI is also successfully demonstrated in multi-contrast tomography, showing great potentials in high-resolution full-field imaging applications, such as in vivo biomedical imaging. Full article

(This article belongs to the Special Issue X-ray Digital Radiography and Computed Tomography)

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29 pages, 12358 KiB

Open AccessArticle

A Continuity Flow Based Tomographic Reconstruction Algorithm for 4D Multi-Beam High Temporal—Low Angular Sampling

by Axel Henningsson and Stephen A. Hall

J. Imaging 2021, 7(11), 246; https://doi.org/10.3390/jimaging7110246 - 20 Nov 2021

Cited by 3 | Viewed by 2199

Abstract

A mathematical framework and accompanying numerical algorithm exploiting the continuity equation for 4D reconstruction of spatiotemporal attenuation fields from multi-angle full-field transmission measurements is presented. The algorithm is geared towards rotation-free dynamic multi-beam X-ray tomography measurements, for which angular information is sparse but [...] Read more.

A mathematical framework and accompanying numerical algorithm exploiting the continuity equation for 4D reconstruction of spatiotemporal attenuation fields from multi-angle full-field transmission measurements is presented. The algorithm is geared towards rotation-free dynamic multi-beam X-ray tomography measurements, for which angular information is sparse but the temporal information is rich. 3D attenuation maps are recovered by propagating an initial discretized density volume in time according to the advection equations using the Finite Volumes method with a total variation diminishing monotonic upstream-centered scheme (TVDMUSCL). The benefits and limitations of the algorithm are explored using dynamic granular system phantoms modelled via discrete elements and projected by an analytical ray model independent from the numerical ray model used in the reconstruction scheme. Three phantom scenarios of increasing complexity are presented and it is found that projections from only a few (unknowns:equations > 10) angles can be sufficient for characterisation of the 3D attenuation field evolution in time. It is shown that the artificial velocity field produced by the algorithm sub-iteration, which is used to propagate the attenuation field, can to some extent approximate the true kinematics of the system. Furthermore, it is found that the selection of a temporal interpolation scheme for projection data can have a significant impact on error build up in the reconstructed attenuation field. Full article

(This article belongs to the Special Issue X-ray Digital Radiography and Computed Tomography)

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26 pages, 6633 KiB

Open AccessArticle

Analysis, Design and Realization of a Furnace for In Situ Wettability Experiments at High Temperatures under X-ray Microtomography

by Roberto Fedele, Fareeha Hameed, Nicola Cefis and Gabriele Vergani

J. Imaging 2021, 7(11), 240; https://doi.org/10.3390/jimaging7110240 - 15 Nov 2021

Cited by 2 | Viewed by 3398

Abstract

In this study, we analyzed the problem of a compact furnace, to be used for in situ experiments in a cone-beam X-ray microtomography commercial system. The design process was accomplished and outlined through its main steps, until the realization of a prototype. The [...] Read more.

In this study, we analyzed the problem of a compact furnace, to be used for in situ experiments in a cone-beam X-ray microtomography commercial system. The design process was accomplished and outlined through its main steps, until the realization of a prototype. The furnace was conceived to carry out wettability experiments at temperatures up to 700 °C and under inert atmosphere on sessile droplets of a molten metal alloy, with a few millimeters diameter, posed on a thin ceramic substrate. X-ray imaging of the molten droplet is expected to permit an accurate three-dimensional reconstruction of the droplet profile and a robust estimation of the related quantities (such as the contact angle and the surface tension) utilized for the assessment of metal-ceramic joints by brazing. The challenges faced during this project, mostly related to the constraints of the setup, and the novel solutions implemented were discussed also with the support of analytical and numerical tools, in terms of interaction of X-rays with matter, geometry and working principle, heat transfer and insulation, material selection. Full article

(This article belongs to the Special Issue X-ray Digital Radiography and Computed Tomography)

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13 pages, 1549 KiB

Open AccessArticle

Impacts of Phantom Off-Center Positioning on CT Numbers and Dose Index CTDIv: An Evaluation of Two CT Scanners from GE

by Xiaoming Zheng, Lachlan Gutsche, Yazan Al-Hayek, Johanna Stanton, Wiam Elshami and Kelsey Jensen

J. Imaging 2021, 7(11), 235; https://doi.org/10.3390/jimaging7110235 - 10 Nov 2021

Cited by 9 | Viewed by 2388

Abstract

The purpose of this work is to evaluate the impacts of body off-center positioning on CT numbers and dose index CTDIv of two scanners from GE. HD750 and APEX scanners were used to acquire a PBU60 phantom of Kagaku and a 062M phantom [...] Read more.

The purpose of this work is to evaluate the impacts of body off-center positioning on CT numbers and dose index CTDIv of two scanners from GE. HD750 and APEX scanners were used to acquire a PBU60 phantom of Kagaku and a 062M phantom of CIRS respectively. CT images were acquired at various off-center positions under automatic tube current modulation using various peak voltages. CTDIv were recorded for each of the acquisitions. An abdomen section of the PBU60 phantom was used for CT number analysis and tissue inserts of the 062M phantom were filled with water balloons to mimic the human abdomen. CT numbers of central regions of interests were averaged using the Fiji software. As phantoms were lifted above the iso-center, both CTDIv and CT numbers were increased for the HD750 scanner whilst they were approximately constant for the APEX scanner. The measured sizes of anterior-posterior projection images were also increased for both scanners whilst the sizes of lateral projection images were increased for the HD750 scanner but decreased for the APEX scanner. Off-center correction algorithms were implemented in the APEX scanner. Matching the X-ray projection center with the system’s iso-center could improve the accuracy of CT imaging. Full article

(This article belongs to the Special Issue X-ray Digital Radiography and Computed Tomography)

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11 pages, 4958 KiB

Open AccessArticle

Illuminating the Imperceptible, Researching Mina’i Ceramics with Digital Imaging Techniques

by Dana Norris and Oliver Watson

J. Imaging 2021, 7(11), 233; https://doi.org/10.3390/jimaging7110233 - 8 Nov 2021

Cited by 2 | Viewed by 2451

Abstract

Mina’i ceramics dating to the late 12th and early 13th century made in the Kashan region of Iran represent a novel period of overglaze enamelling technology in ceramic history. New colours were used to produce stylistically attractive and dynamic polychrome motifs. Due to [...] Read more.

Mina’i ceramics dating to the late 12th and early 13th century made in the Kashan region of Iran represent a novel period of overglaze enamelling technology in ceramic history. New colours were used to produce stylistically attractive and dynamic polychrome motifs. Due to their archaeological context, and popularity in the art market since the mid-20th century, these objects often have complex conditions involving reconstruction and overpainting. The aesthetic and technological significance of these pieces warrants further study, but in practice, removing restorations can lead to structural destabilisation, requiring time-consuming and potentially unplanned for conservation treatment. To determine if it is possible to gain useful information from the study of these artworks without disturbing existing restorations, a group of objects were drawn from the Sarikhani and Ashmolean Museum of Art and Archaeology collections. The objective of this project was twofold, first to assess the merits of the imaging techniques for understanding condition, and second to propose a protocol for imaging with the aim of encouraging collaborative projects with international partners. The techniques used in this study include digital photography under visible and ultraviolet light, infrared reflectography, and radiography. The results show that important information invisible to the naked eye can be obtained about the decorative surfaces, using ultraviolet light and infrared reflectography. Digital radiography proved to be equally effective when studying the condition of the ceramic body. The results of this project were used to produce guidance on these techniques as a collaborative documentation package for the study of Mina’i ceramics. Full article

(This article belongs to the Special Issue X-ray Digital Radiography and Computed Tomography)

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13 pages, 6268 KiB

Open AccessArticle

X-ray Imaging Investigation on the Gilding Technique of an Ancient Egyptian Taweret Wooden Statuette

by Luisa Vigorelli, Alessandro Re, Laura Guidorzi, Tiziana Cavaleri, Paola Buscaglia, Marco Nervo, Federica Facchetti, Matilde Borla, Sabrina Grassini and Alessandro Lo Giudice

J. Imaging 2021, 7(11), 229; https://doi.org/10.3390/jimaging7110229 - 29 Oct 2021

Cited by 13 | Viewed by 3144

Abstract

Diagnostic physical methods are increasingly applied to Cultural Heritage both for scientific investigations and conservation purposes. In particular, the X-ray imaging techniques of computed tomography (CT) and digital radiography (DR) are non-destructive investigation methods to study an object, being able to give information [...] Read more.

Diagnostic physical methods are increasingly applied to Cultural Heritage both for scientific investigations and conservation purposes. In particular, the X-ray imaging techniques of computed tomography (CT) and digital radiography (DR) are non-destructive investigation methods to study an object, being able to give information on its inner structure. In this paper, we present the results of the X-ray imaging study on an ancient Egyptian statuette (Late Period 722–30 BCE) belonging to the collection of Museo Egizio in Torino and representing an Egyptian goddess called Taweret, carved on wood and gilded with some colored details. Since few specific studies have been focused on materials and techniques used in Ancient Egypt for gilding, a detailed investigation was started in order to verify the technical features of the decoration in this sculpture. Specifically, DR and CT analyses have been performed at the Centro Conservazione e Restauro “La Venaria Reale” (CCR), with a new high resolution flat-panel detector, that allowed us to perform tomographic analysis reaching a final resolution better than the one achievable with the previous apparatus operating in the CCR. Full article

(This article belongs to the Special Issue X-ray Digital Radiography and Computed Tomography)

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9 pages, 3408 KiB

Open AccessArticle

Neutron and Synchrotron Imaging Studies of Preservation State of Metal of Cultural Heritage Objects

by Ekaterina Kovalenko, Mikhail Murashev, Konstantin Podurets, Elena Tereschenko and Ekaterina Yatsishina

J. Imaging 2021, 7(11), 224; https://doi.org/10.3390/jimaging7110224 - 26 Oct 2021

Cited by 2 | Viewed by 2319

Abstract

This paper analyzes the results of studies carried out at the National Research Center “Kurchatov Institute”, Moscow, using the methods of neutron and X-ray synchrotron tomography from the point of view of the preservation state of metal objects. Objects damaged by corrosion and [...] Read more.

This paper analyzes the results of studies carried out at the National Research Center “Kurchatov Institute”, Moscow, using the methods of neutron and X-ray synchrotron tomography from the point of view of the preservation state of metal objects. Objects damaged by corrosion and exposure to fire were the focus of this study. To identify regions of metal preservation, the diffraction contrast on grains of metal, observed in tomographic projections, was used. The simultaneous use of neutron and synchrotron imaging is shown to be a powerful tool for identification of the constituents of an object. Full article

(This article belongs to the Special Issue X-ray Digital Radiography and Computed Tomography)

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10 pages, 4728 KiB

Open AccessArticle

Single-Shot Multicontrast X-ray Imaging for In Situ Visualization of Chemical Reaction Products

by Margarita Zakharova, Andrey Mikhaylov, Vitor Vlnieska and Danays Kunka

J. Imaging 2021, 7(11), 221; https://doi.org/10.3390/jimaging7110221 - 23 Oct 2021

Cited by 3 | Viewed by 3400

Abstract

We present the application of single-shot multicontrast X-ray imaging with an inverted Hartmann mask to the time-resolved in situ visualization of chemical reaction products. The real-time monitoring of an illustrative chemical reaction indicated the formation of the precipitate by the absorption, differential phase, [...] Read more.

We present the application of single-shot multicontrast X-ray imaging with an inverted Hartmann mask to the time-resolved in situ visualization of chemical reaction products. The real-time monitoring of an illustrative chemical reaction indicated the formation of the precipitate by the absorption, differential phase, and scattering contrast images obtained from a single projection. Through these contrast channels, the formation of the precipitate along the mixing line of the reagents, the border between the solid and the solution, and the presence of the scattering structures of 100–200 nm sizes were observed. The measurements were performed in a flexible and robust setup, which can be tailored to various imaging applications at different time scales. Full article

(This article belongs to the Special Issue X-ray Digital Radiography and Computed Tomography)

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15 pages, 1049 KiB

Open AccessArticle

Signal Retrieval from Non-Sinusoidal Intensity Modulations in X-ray and Neutron Interferometry Using Piecewise-Defined Polynomial Function

by Simon Pinzek, Alex Gustschin, Tobias Neuwirth, Alexander Backs, Michael Schulz, Julia Herzen and Franz Pfeiffer

J. Imaging 2021, 7(10), 209; https://doi.org/10.3390/jimaging7100209 - 11 Oct 2021

Cited by 2 | Viewed by 2261

Abstract

Grating-based phase-contrast and dark-field imaging systems create intensity modulations that are usually modeled with sinusoidal functions to extract transmission, differential-phase shift, and scatter information. Under certain system-related conditions, the modulations become non-sinusoidal and cause artifacts in conventional processing. To account for that, we [...] Read more.

Grating-based phase-contrast and dark-field imaging systems create intensity modulations that are usually modeled with sinusoidal functions to extract transmission, differential-phase shift, and scatter information. Under certain system-related conditions, the modulations become non-sinusoidal and cause artifacts in conventional processing. To account for that, we introduce a piecewise-defined periodic polynomial function that resembles the physical signal formation process, modeling convolutions of binary periodic functions. Additionally, we extend the model with an iterative expectation-maximization algorithm that can account for imprecise grating positions during phase-stepping. We show that this approach can process a higher variety of simulated and experimentally acquired data, avoiding most artifacts. Full article

(This article belongs to the Special Issue X-ray Digital Radiography and Computed Tomography)

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8 pages, 1304 KiB

Open AccessArticle

Lobular Breast Cancer Conspicuity on Digital Breast Tomosynthesis Compared to Synthesized 2D Mammography: A Multireader Study

by Giovanna Romanucci, Lisa Zantedeschi, Anna Ventriglia, Sara Mercogliano, Maria Vittoria Bisighin, Loredana Cugola, Paola Bricolo, Rossella Rella, Marta Mandarà, Chiara Benassuti, Andrea Caneva and Francesca Fornasa

J. Imaging 2021, 7(9), 185; https://doi.org/10.3390/jimaging7090185 - 12 Sep 2021

Cited by 4 | Viewed by 3768

Abstract

Objectives: To compare the conspicuity of lobular breast cancers at digital breast tomosynthesis (DBT) versus synthesized 2D mammography (synt2D). Materials and methods: Seventy-six women (mean age 61.2 years, range 50–74 years) submitted to biopsy in our institution, from 2019 to 2021, with proven [...] Read more.

Objectives: To compare the conspicuity of lobular breast cancers at digital breast tomosynthesis (DBT) versus synthesized 2D mammography (synt2D). Materials and methods: Seventy-six women (mean age 61.2 years, range 50–74 years) submitted to biopsy in our institution, from 2019 to 2021, with proven invasive lobular breast cancer (ILC) were enrolled in this retrospective study. The participants underwent DBT and synt2D. Five breast radiologists, with different years of experience in breast imaging, independently assigned a conspicuity score (ordinal 6-point scale) to DBT and synt2D. Lesion conspicuity was compared, for each reader, between the synt2D overall conspicuity interpretation and DBT overall conspicuity interpretation using a Wilcoxon matched pairs test. Results: A total of 50/78 (64%) cancers were detected on both synt2D and DBT by all the readers, while 28/78 (26%) cancers where not recognized by at least one reader on synt2D. For each reader, in comparison with synt2D, DBT increased significantly the conspicuity of ILC (p < 0.0001). The raw proportion of high versus low conspicuity by modality confirmed that cancers were more likely to have high conspicuity at DBT than synt2D. Conclusions: ILCs were more likely to have high conspicuity at DBT than at synt2D, increasing the chances of the detection of ILC breast cancer. Full article

(This article belongs to the Special Issue X-ray Digital Radiography and Computed Tomography)

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13 pages, 5498 KiB

Open AccessArticle

Noise Reduction for Single-Shot Grating-Based Phase-Contrast Imaging at an X-ray Backlighter

by Stephan Schreiner, Bernhard Akstaller, Lisa Dietrich, Pascal Meyer, Paul Neumayer, Max Schuster, Andreas Wolf, Bernhard Zielbauer, Veronika Ludwig, Thilo Michel, Gisela Anton and Stefan Funk

J. Imaging 2021, 7(9), 178; https://doi.org/10.3390/jimaging7090178 - 5 Sep 2021

Cited by 6 | Viewed by 2946

Abstract

X-ray backlighters allow the capture of sharp images of fast dynamic processes due to extremely short exposure times. Moiré imaging enables simultaneously measuring the absorption and differential phase-contrast (DPC) of these processes. Acquiring images with one single shot limits the X-ray photon flux, [...] Read more.

X-ray backlighters allow the capture of sharp images of fast dynamic processes due to extremely short exposure times. Moiré imaging enables simultaneously measuring the absorption and differential phase-contrast (DPC) of these processes. Acquiring images with one single shot limits the X-ray photon flux, which can result in noisy images. Increasing the photon statistics by repeating the experiment to gain the same image is not possible if the investigated processes are dynamic and chaotic. Furthermore, to reconstruct the DPC and transmission image, an additional measurement captured in absence of the object is required. For these reference measurements, shot-to-shot fluctuations in X-ray spectra and a source position complicate the averaging of several reference images for noise reduction. Here, two approaches of processing multiple reference images in combination with one single object image are evaluated regarding the image quality. We found that with only five reference images, the contrast-to-noise ratio can be improved by approximately 13% in the DPC image. This promises improvements for short-exposure single-shot acquisitions of rapid processes, such as laser-produced plasma shock-waves in high-energy density experiments at backlighter X-ray sources such as the PHELIX high-power laser facility. Full article

(This article belongs to the Special Issue X-ray Digital Radiography and Computed Tomography)

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9 pages, 6782 KiB

Open AccessArticle

Suppression of Cone-Beam Artefacts with Direct Iterative Reconstruction Computed Tomography Trajectories (DIRECTT)

by Sotirios Magkos, Andreas Kupsch and Giovanni Bruno

J. Imaging 2021, 7(8), 147; https://doi.org/10.3390/jimaging7080147 - 15 Aug 2021

Cited by 4 | Viewed by 2436

Abstract

The reconstruction of cone-beam computed tomography data using filtered back-projection algorithms unavoidably results in severe artefacts. We describe how the Direct Iterative Reconstruction of Computed Tomography Trajectories (DIRECTT) algorithm can be combined with a model of the artefacts for the reconstruction of such [...] Read more.

The reconstruction of cone-beam computed tomography data using filtered back-projection algorithms unavoidably results in severe artefacts. We describe how the Direct Iterative Reconstruction of Computed Tomography Trajectories (DIRECTT) algorithm can be combined with a model of the artefacts for the reconstruction of such data. The implementation of DIRECTT results in reconstructed volumes of superior quality compared to the conventional algorithms. Full article

(This article belongs to the Special Issue X-ray Digital Radiography and Computed Tomography)

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14 pages, 5483 KiB

Open AccessArticle

CORONA-Net: Diagnosing COVID-19 from X-ray Images Using Re-Initialization and Classification Networks

by Sherif Elbishlawi, Mohamed H. Abdelpakey, Mohamed S. Shehata and Mostafa M. Mohamed

J. Imaging 2021, 7(5), 81; https://doi.org/10.3390/jimaging7050081 - 28 Apr 2021

Cited by 10 | Viewed by 4339

Abstract

The COVID-19 pandemic has been deemed a global health pandemic. The early detection of COVID-19 is key to combating its outbreak and could help bring this pandemic to an end. One of the biggest challenges in combating COVID-19 is accurate testing for the [...] Read more.

The COVID-19 pandemic has been deemed a global health pandemic. The early detection of COVID-19 is key to combating its outbreak and could help bring this pandemic to an end. One of the biggest challenges in combating COVID-19 is accurate testing for the disease. Utilizing the power of Convolutional Neural Networks (CNNs) to detect COVID-19 from chest X-ray images can help radiologists compare and validate their results with an automated system. In this paper, we propose a carefully designed network, dubbed CORONA-Net, that can accurately detect COVID-19 from chest X-ray images. CORONA-Net is divided into two phases: (1) The reinitialization phase and (2) the classification phase. In the reinitialization phase, the network consists of encoder and decoder networks. The objective of this phase is to train and initialize the encoder and decoder networks by a distribution that comes out of medical images. In the classification phase, the decoder network is removed from CORONA-Net, and the encoder network acts as a backbone network to fine-tune the classification phase based on the learned weights from the reinitialization phase. Extensive experiments were performed on a publicly available dataset, COVIDx, and the results show that CORONA-Net significantly outperforms the current state-of-the-art networks with an overall accuracy of 95.84%. Full article

(This article belongs to the Special Issue X-ray Digital Radiography and Computed Tomography)

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23 pages, 1064 KiB

Open AccessReview

An Overview of X-ray Photon Counting Spectral Imaging (x-CSI) with a Focus on Gold Nanoparticle Quantification in Oncology

by Oliver L. P. Pickford Scienti and Dimitra G. Darambara

J. Imaging 2022, 8(1), 4; https://doi.org/10.3390/jimaging8010004 - 31 Dec 2021

Cited by 4 | Viewed by 2982

Abstract

This review article offers an overview of the differences between traditional energy integrating (EI) X-ray imaging and the new technique of X-ray photon counting spectral imaging (x-CSI). The review is motivated by the need to image gold nanoparticles (AuNP) in vivo if they [...] Read more.

This review article offers an overview of the differences between traditional energy integrating (EI) X-ray imaging and the new technique of X-ray photon counting spectral imaging (x-CSI). The review is motivated by the need to image gold nanoparticles (AuNP) in vivo if they are to be used clinically to deliver a radiotherapy dose-enhancing effect (RDEE). The aim of this work is to familiarise the reader with x-CSI as a technique and to draw attention to how this technique will need to develop to be of clinical use for the described oncological applications. This article covers the conceptual differences between x-CSI and EI approaches, the advantages of x-CSI, constraints on x-CSI system design, and the achievements of x-CSI in AuNP quantification. The results of the review show there are still approximately two orders of magnitude between the AuNP concentrations used in RDEE applications and the demonstrated detection limits of x-CSI. Two approaches to overcome this were suggested: changing AuNP design or changing x-CSI system design. Optimal system parameters for AuNP detection and general spectral performance as determined by simulation studies were different to those used in the current x-CSI systems, indicating potential gains that may be made with this approach. Full article

(This article belongs to the Special Issue X-ray Digital Radiography and Computed Tomography)

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13 pages, 1645 KiB

Open AccessReview

Principles and Perspectives of Radiographic Imaging with Muons

by Luigi Cimmino

J. Imaging 2021, 7(12), 253; https://doi.org/10.3390/jimaging7120253 - 26 Nov 2021

Cited by 6 | Viewed by 4150

Abstract

Radiographic imaging with muons, also called Muography, is based on the measurement of the absorption of muons, generated by the interaction of cosmic rays with the earth’s atmosphere, in matter. Muons are elementary particles with high penetrating power, a characteristic that makes them [...] Read more.

Radiographic imaging with muons, also called Muography, is based on the measurement of the absorption of muons, generated by the interaction of cosmic rays with the earth’s atmosphere, in matter. Muons are elementary particles with high penetrating power, a characteristic that makes them capable of crossing bodies of dimensions of the order of hundreds of meters. The interior of bodies the size of a pyramid or a volcano can be seen directly with the use of this technique, which can rely on highly segmented muon trackers. Since the muon flux is distributed in energy over a wide spectrum that depends on the direction of incidence, the main difference with radiography made with X-rays is in the source. The source of muons is not tunable, neither in energy nor in direction; to improve the signal-to-noise ratio, muography requires large instrumentation, long time data acquisition and high background rejection capacity. Here, we present the principles of the Muography, illustrating how radiographic images can be obtained, starting from the measurement of the attenuation of the muon flux through an object. It will then be discussed how recent technologies regarding artificial intelligence can give an impulse to this methodology in order to improve its results. Full article

(This article belongs to the Special Issue X-ray Digital Radiography and Computed Tomography)

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27 pages, 105251 KiB

Open AccessReview

Micro-CT for Biological and Biomedical Studies: A Comparison of Imaging Techniques

by Kleoniki Keklikoglou, Christos Arvanitidis, Georgios Chatzigeorgiou, Eva Chatzinikolaou, Efstratios Karagiannidis, Triantafyllia Koletsa, Antonios Magoulas, Konstantinos Makris, George Mavrothalassitis, Eleni-Dimitra Papanagnou, Andreas S. Papazoglou, Christina Pavloudi, Ioannis P. Trougakos, Katerina Vasileiadou and Angeliki Vogiatzi

J. Imaging 2021, 7(9), 172; https://doi.org/10.3390/jimaging7090172 - 1 Sep 2021

Cited by 38 | Viewed by 7503

Abstract

Several imaging techniques are used in biological and biomedical studies. Micro-computed tomography (micro-CT) is a non-destructive imaging technique that allows the rapid digitisation of internal and external structures of a sample in three dimensions and with great resolution. In this review, the strengths [...] Read more.

Several imaging techniques are used in biological and biomedical studies. Micro-computed tomography (micro-CT) is a non-destructive imaging technique that allows the rapid digitisation of internal and external structures of a sample in three dimensions and with great resolution. In this review, the strengths and weaknesses of some common imaging techniques applied in biological and biomedical fields, such as optical microscopy, confocal laser scanning microscopy, and scanning electron microscopy, are presented and compared with the micro-CT technique through five use cases. Finally, the ability of micro-CT to create non-destructively 3D anatomical and morphological data in sub-micron resolution and the necessity to develop complementary methods with other imaging techniques, in order to overcome limitations caused by each technique, is emphasised. Full article

(This article belongs to the Special Issue X-ray Digital Radiography and Computed Tomography)

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32 pages, 12921 KiB

Open AccessReview

Imaging with Coherent X-rays: From the Early Synchrotron Tests to SYNAPSE

by Giorgio Margaritondo and Yeukuang Hwu

J. Imaging 2021, 7(8), 132; https://doi.org/10.3390/jimaging7080132 - 4 Aug 2021

Cited by 5 | Viewed by 2675

Abstract

The high longitudinal and lateral coherence of synchrotron X-rays sources radically transformed radiography. Before them, the image contrast was almost only based on absorption. Coherent synchrotron sources transformed radiography into a multi-faceted tool that can extract information also from “phase” effects. Here, we [...] Read more.

The high longitudinal and lateral coherence of synchrotron X-rays sources radically transformed radiography. Before them, the image contrast was almost only based on absorption. Coherent synchrotron sources transformed radiography into a multi-faceted tool that can extract information also from “phase” effects. Here, we report a very simple description of the new techniques, presenting them to potential new users without requiring a sophisticated background in advanced physics. We then illustrate the impact of such techniques with a number of examples. Finally, we present the international collaboration SYNAPSE (Synchrotrons for Neuroscience—an Asia-Pacific Strategic Enterprise), which targets the use of phase-contrast radiography to map one full human brain in a few years. Full article

(This article belongs to the Special Issue X-ray Digital Radiography and Computed Tomography)

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