Differences In X-ray Attenuation Research Articles

On the Stability of Pickering and Classical Nanoemulsions: Theory and Experiments

Emulsification is a crucial technique for mixing immiscible liquids into droplets in various industries, such as food, cosmetics, biomedicine, agrochemistry, and petrochemistry. Quantitative analysis of the stability is pivotal before the utilization of these emulsions. Differences in X-ray attenuation for emulsion components and surface relaxation of the droplets may contribute to X-ray CT imaging and low-field NMR spectroscopy as viable techniques to quantify emulsion stability. In this study, Pickering (stabilized solely by nanoparticles) and Classical (stabilized solely by low molecular weight polymers) nanoemulsions were prepared with a high-energy method. NMR and X-ray CT were employed to constantly monitor the two types of nanoemulsions until phase separation. The creaming rates calculated from NMR match well with the results obtained from X-ray CT. Furthermore, we show that Stokes' law coupled with the classical Lifshitz-Slyozov-Wagner theory underestimates the creaming rate of the nanoemulsions compared to the experimental results from NMR and X-ray CT imaging. A new theory is proposed by fully incorporating the effects of Pickering nanoparticles, hydrocarbon types, volume fraction, size distribution, and flocculation on the droplet coarsening. The theoretical results agree well with the experimentally measured creaming rates. It reveals that the attachment of nanoparticles onto a droplet surface decreases the mass transfer for hydrocarbon molecules to move from the bulk aqueous phase into other droplets, thus slowing the Ostwald ripening. Therefore, Pickering nanoemulsions show a better stability behavior compared to Classical nanoemulsions. The impacts of hydrocarbon and emulsification energy on the stability of nanoemulsions are reported. These findings demonstrate that the stability of the nanoemulsions can be manipulated and optimized for a specific application, setting the stage for subsequent investigations of these nanodroplets.

CBCT – RADIOLOGICAL ANATOMY OF THE NASAL CAVITYAND THE PARANASAL SINUSES

At present, modern otorhinolaryngology cannot be imagined without such a research method as computed tomography (CT) – a method of non-destructive layer-by-layer study of the object internal structure, which was proposed in 1972 by A. Kormak. The method is based on the measurement and complex computer processing of the difference in X-ray attenuation by different density tissues. Confidently starting in our country in the 80th of the last century, CT is developing, becoming an increasingly perfect method, practically the main X-ray diagnostics method in otorhinolaryngology. Cone-beam computed tomography (CBCT) was first adapted for potential clinical use in 1982 at the Mayo Clinic Biodynamics Research Laboratory (USA). Initially, the technique found application in angiography, in which soft tissues can be brought in to benefit from the possibility of obtaining high temporal and spatial resolution. Available for wide use in the maxillofacial region diagnosis, CBCT became available in 2001 (New Tom QR DVT 9000, Italy). CBCT is a radiological examination method based on the X-rays use by rotating an X-ray tube around a patient to obtain data. It is mainly used in dental practice, but more and more often this technique is introduced into otolaryngological practice. Because modern devices make it possible to obtain all sinuses images at once and characterize them. The biggest advantage of this study is a much lower ionizing radiation dose along with almost the entire range of traditional CT possibilities. The CBCT use is growing in the clinical arena due to its ability to provide 3D information during interventions, its high diagnostic quality (sub-millimeter resolution), and its short scanning times. However, clinical and anatomical evidence pertaining to its efficacy is lacking. The presented article describes the possibilities of using CBCT to characterize the nose and paranasal sinuses anatomical features.
 The aim. To show the nose and paranasal sinuses X-ray anatomy by retrospective analysis of cone-beam computed tomography images.
 Methods. To study the topographic and anatomical structures of the facial skull in the norm we analyzed 30 CBCT patients’ images (18 men and 12 women aged from 10 to 62 years) in whom there was no nose and paranasal sinuses pathology, or atypical variants of this area development were determined. The study was conducted using Planmeca ProMax® 3D's innovative Maxillofacial tomograph, which covers the entire sinus area, making it an excellent solution for 3D and 2D visualization of the paranasal sinuses. Descriptions are made using Planmeca Romexis viewer software.
 Results. With the help of the modern method of radiological examination, particularly CBCT, it is possible to clearly visualize and differentiate the nose and sinuses’ anatomical structure features. As a result of the analysis, we confirmed the fact that the CBCT use is appropriate in patients. This technique allows not only to see but also to measure various indicators (shape, anatomical formations size; contours;) and to compare the nose and paranasal sinuses bone structures. Also, the 3D reconstructions use makes it possible to compare the positions of different anatomical structures of the facial skull. The CBCT effectiveness for assessing the individual anatomy of the nasal cavity and paranasal sinuses has been shown, which can be used both for patients’ preoperative preparation and at the stage of diagnosis and treatment of the nasal cavity and maxillary sinuses various diseases.

3D zoning of barium in alkali feldspar

Abstract Interpretation of chemical zoning within igneous minerals is critical to many petrologic studies. Zoning in minerals, however, is commonly observed in thin sections or grain mounts, which are random 2D slices of a 3D system. Use of these 2D sections to infer 3D geometries requires a set of assumptions, often not directly tested, introduces several issues, and results in partial loss of zoning information. Computed X-ray microtomography (microCT) offers a way to assess 3D zoning in minerals at high resolution. To observe 3D mineral zoning using microCT, however, requires that zoning is observable as differences in X-ray attenuation. Sanidine, with its affinity for Ba in the crystal lattice, can display large, abrupt variations in Ba that are related to various magma reservoir processes. These changes in Ba also significantly change the X-ray attenuation coefficient of sanidine, allowing for discrete mineral zones to be mapped in 3D using microCT. Here we utilize microCT to show 3D chemical zoning within natural sanidines from a suite of volcanic eruptions throughout the geologic record. We also show that changes in microCT grayscale in sanidine are largely controlled by changes in Ba. Starting with 3D mineral reconstructions, we simulate thin-section making by generating random 2D slices across a mineral zone to show that slicing orientation alone can drastically change the apparent width and slope of composition transitions between different zones. Furthermore, we find that chemical zoning in sanidine can commonly occur in more complex geometries than the commonly interpreted concentric zoning patterns. Together, these findings have important implications for methodologies that rely on the interpretation of chemical zoning within minerals and align with previously published numerical models that show how chemical gradient geometries are affected by random sectioning during common sample preparation methods (e.g., thin sections and round mounts).

A bibliometric and social network analysis perspective of X‐ray phase‐contrast imaging in medical imaging

IntroductionPhase‐contrast imaging (PCI) is a novel technology that can visualise variations in X‐ray refraction (phase contrast) in addition to differences in X‐ray attenuation (absorption contrast). Compared to radiography using conventional methods (i.e. absorption‐based imaging), PCI techniques can potentially produce images with higher contrast‐to‐noise ratio and superior spatial resolution at the same or lower radiation doses. This has led PCI to be explored for implementation in medical imaging. While interest in this research field is increasing, the whole body of PCI research in medical imaging has been under‐investigated. This paper provides an overview of PCI literature and then focusses on evaluating its development within the scope of medical imaging.MethodsBibliographic data between 1995 and 2018 were used to visualise collaboration networks between countries, institutions and authors. Social network analysis techniques were implemented to measure these networks in terms of centrality and cohesion. These techniques also assisted in the exploration of underlying research paradigms of clinical X‐ray PCI investigations.ResultsForty‐one countries, 592 institutions and 2073 authors contributed 796 investigations towards clinical PCI research. The most influential contributors and network collaboration characteristics were identified. Italy was the most influential country, with the European Synchrotron Radiation Facility being the most influential institution. At an author level, F. Pfeiffer was found to be the most influential researcher. Among various PCI techniques, grating interferometry was the most investigated, while computed tomography was the most frequently examined modality.ConclusionsBy gaining an understanding of collaborations and trends within clinical X‐ray PCI research, the links between existing collaborators were identified, which can aid future collaborations between emerging and established collaborators. Moreover, exploring the paradigm of past investigations can shape future research – well‐researched PCI techniques may be studied to bring X‐ray PCI closer to clinical implementation, or the potential of seldom‐investigated techniques may be explored.

Using convolutional neural networks to discriminate between cysts and masses in Monte Carlo-simulated dual-energy mammography.

A substantial percentage of recalls (up to 20%) in screening mammography is attributed to extended round lesions. Benign fluid-filled breast cysts often appear similar to solid tumors in conventional mammograms. Spectral imaging (dual-energy or photon-counting mammography) has been shown to discriminate between cysts and solid masses with clinically acceptable accuracy. This work explores the feasibility of using convolutional neural networks (CNNs) for this task. A series of Monte Carlo experiments was conducted with digital breast phantoms and embedded synthetic lesions to produce realistic dual-energy images of both lesion types. We considered such factors as nonuniform anthropomorphic background, size of the mass, breast compression thickness, and variability in lesion x-ray attenuation. These data then were used to train a deep neural network (ResNet-18) to learn the differences in x-ray attenuation of cysts and masses. Our simulation results showed that the CNN-based classifier could reliably discriminate between cystic and solid mass round lesions in dual-energy images with an area under the receiver operating characteristic curve (ROC AUC) of 0.98 or greater. The proposed approach showed promising performance and ease of implementation, and could be applied to novel photon-counting detector-based spectral mammography systems.

A Contrast Enhancement Model for X-Ray Mammograms Using Modified Local s-Curve Transformation Based on Multi-Objective Optimization

The biased X-ray field and the subtle difference in X-ray attenuation between normal and abnormal breast tissues prevent the biomedical sensors to generate mammograms with good quality. These are the common imperfections in the acquisition systems (sensor) of Mammography which contribute towards the degradation of mammogram image quality. This paper aims to develop a contrast enhancement model for mammograms so that the human or machine vision can distinguish easily among the variants of breast lesions and predict their severity. The proposed mammogram enhancement model exploits locally the proprieties of the sigmoidal function based on multi-objective Genetic Algorithm for improving the contrast of lesions along with a simultaneous increment in various Image Quality Assessment (IQA) parameters like: $\textit {EME}$ , $\textit {EC}$ , $\textit {AMBEn}$ and $\textit {FSIM}$ . Herein, the multi-objective optimization problem is transformed into a single-objective optimization to find a unique solution for mammogram enhancement. An increase in these IQA metrics is indicative of better contrast, edge content, and conservation of brightness and other diagnostics information. Simulations of the proposed enhancement model are carried out on mammograms from the mini-MIAS database for benchmarking and validation of results.

Does anthropomorphic model design in ex vivo studies affect diagnostic accuracy for dental root fracture using CBCT?

The evidence for diagnostic accuracy using cone beam computed tomography (CBCT) for dental applications depends heavily on ex vivo research, but there is little knowledge of whether the model used affects the diagnostic accuracy results. The objective of this study was to determine the impact of different designs of anthropomorphic models on diagnostic accuracy for the specific task of dental root fracture detection. Horizontal or oblique root fracture was induced in 24 of 48 permanent maxillary incisors. The 48 teeth were scanned by CBCT using standard clinical exposure factors on five occasions, each with a different model design. Scans were viewed by five dental and maxillofacial radiologists, who each made a forced diagnosis of fracture or no fracture in each root and a judgment on root fracture using a five-point confidence scale. Sensitivity (Se), specificity (Sp) and areas under receiver operating characteristic (ROC) curve (Az) were calculated for each observer for each model. There were no significant differences between the diagnostic accuracy measurements recorded using different models. There were, however, numerous significant differences between observers using the same anthropomorphic model. Despite the differences in X-ray attenuation between the five model designs, the results suggest that the anthropomorphic model does not affect the results of diagnostic accuracy studies on root fracture using this CBCT machine at standard clinical exposures. This provides some confidence in the previously published evidence. The interobserver diagnosis differences indicate that research using only two observers could provide misleading results.

The visible skeleton 2.0: phenotyping of cartilage and bone in fixed vertebrate embryos and foetuses based on X-ray microCT.

For decades, clearing and staining with Alcian Blue and Alizarin Red has been the gold standard to image vertebrate skeletal development. Here, we present an alternate approach to visualise bone and cartilage based on X-ray microCT imaging, which allows the collection of genuine 3D data of the entire developing skeleton at micron resolution. Our novel protocol is based on ethanol fixation and staining with Ruthenium Red, and efficiently contrasts cartilage matrix, as demonstrated in whole E16.5 mouse foetuses and limbs of E14 chicken embryos. Bone mineral is well preserved during staining, thus the entire embryonic skeleton can be imaged at high contrast. Differences in X-ray attenuation of ruthenium and calcium enable the spectral separation of cartilage matrix and bone by dual energy microCT (microDECT). Clearing of specimens is not required. The protocol is simple and reproducible. We demonstrate that cartilage contrast in E16.5 mouse foetuses is adequate for fast visual phenotyping. Morphometric skeletal parameters are easily extracted. We consider the presented workflow to be a powerful and versatile extension to the toolkit currently available for qualitative and quantitative phenotyping of vertebrate skeletal development.

K-edge-based interior tomography

Interior tomography reconstructs a region of interest using truncated projection data, but it is subject to the ill-posedness of interior tomography. With the photon-counting detector, K-edge imaging uses data in the low and high energy bins around the K-edge of a contrast agent, and can faithfully recover true image contrast for improved diagnosis. The purpose of this paper is to reconstruct a region of interest inside a patient assuming the existence of a known K-edge material. In this case, there is a significant difference in x-ray attenuation around the K-edge, but these attenuation coefficients are inter-related to guide updating an intermediate reconstruction until a stopping criterion is satisfied. In our study, new interior tomography algorithms were developed without any major computational overhead, and several phantoms were used to validate the algorithms. The proposed methods are advantageous relative to the existing interior tomography algorithms, because of the available spectral information in the form of a known K-edge material.

Detection and segmentation of mechanical damage in concrete with X-Ray microtomography

X-Ray computed microtomography (micro-CT) is an imaging technique that has seen increasing application in the field of experimental mechanics for its ability to take non-destructive, precise, 3D measurements of material morphology. The microstructure of a heterogeneous material with distinct constituent phases can be segregated using micro-CT as a result of the differences in X-Ray attenuation between the various phases. However, detection and segmentation of different features within the same phase requires more complex methods beyond the segmentation by X-Ray attenuation rate. For example, cracks and porosity are recognized as the same phase by X-Ray attenuation-based segmentation methods. However, these two microstructural features are the result of different processes, as pores are inherent to the microstructure of cementitious materials, while cracks are often considered to be material damage. This study aims to compare a novel quasi-3D crack detection technique with two other techniques reported in previously published studies, with the goal of finding the most effective technique for identifying cracks/damage in concrete specimens subjected to controlled intermittent dynamic mechanical loadings. The results show that while the previously reported techniques work well for detecting cracks in concrete specimens with discrete porosity and/or large interconnected crack networks, they were not as effective in distinguishing small cracks from clusters of voids. The quasi-3D geometric segmentation technique proposed in this study is shown to perform well across all crack length scales even in concrete specimens with interconnected porosity.

Breast-density measurement using photon-counting spectral mammography.

To evaluate a method for measuring breast density using photon-counting spectral mammography. Breast density is an indicator of breast cancer risk and diagnostic accuracy in mammography, and can be used as input to personalized screening, treatment monitoring and dose estimation. The measurement method employs the spectral difference in x-ray attenuation between adipose and fibro-glandular tissue, and does not rely on any a priori information. The method was evaluated using phantom measurements on tissue-equivalent material (slabs and breast-shaped phantoms) and using clinical data from a screening population (n=1329). A state-of-the-art nonspectral method for breast-density assessment was used for benchmarking. The precision of the spectral method was estimated to be 1.5-1.8 percentage points (pp) breast density. Expected correlations were observed in the screening population for thickness versus breast density, dense volume, breast volume, and compression height. Densities ranged between 4.5% and 99.6%, and exhibited a skewed distribution with a mode of 12.5%, a median of 18.3%, and a mean of 23.7%. The precision of the nonspectral method was estimated to be 2.7-2.8 pp. The major uncertainty of the nonspectral method originated from the thickness estimate, and in particular thin/dense breasts posed problems compared to the spectral method. The spectral method yielded reasonable results in a screening population with a precision approximately two times that of the nonspectral method, which may improve or enable applications of breast-density measurement on an individual basis such as treatment monitoring and personalized screening.

Application of PET/CT in Oncologic Imaging

Background: There are many challenges in oncologic imaging including: more accurate staging, determine site with highest probability of tumor existence for biopsy, especially for brain tumors because of the sensitive anatomical position, determine the exact location of the tumor for radiotherapy treatment planning and etc. Positron emission tomography (PET) is imaging modality which provides some special functional information. The basis of the PET system is detection of tow photons which are generated by positron/electron encounter which occurs directly after positron emission by radionuclide. However, it is powerless in providing anatomical information. Computed tomography (CT) generates three dimensional reconstructions of patients anatomy based on differences in X-ray attenuation. Combination of PET and CT is able to provide anatomical and physiological information of patients synchronizes. Objectives: In this paper, we evaluate application of PET/CT for improve oncologic imaging. Methods: The papers were searched in PubMed and Scopus databases with the relevant key words including, PET/CT, Oncologic Imaging and Cancer staging. Results: The most relevant biomarker for PET is 8F- FDG (F-18 Fluorodeoxyglucose), which is incorporated into malignant cells by glucose transporters which are over expressed by cancer cells. CT is the common imaging modality in diagnosis the cancers. It is due to its speed, high special resolution and relative cost-effectiveness. The combination of these two modalities in one system produced PET/CT system which is more accurate than these two imaging modalities separately and enhances the sensitivity and specificity of diagnosis. For example in a study which used PET/CT for differentiation between the malignant and benign disease Presacral, sensitivity, specificity, the positive predictive value and the negative predictive value are 100%, 96%, 88% and 100% respectively. In another study, which was done for preradiotherapy staging of head-and-neck SCCs, it was shown that FDG-PET/CT detected 17 of 17 heminecks and 26 of 27 nodal zones histologically positive by dissection (100% and 96% sensitivity, respectively). Conclusions: PET/CT can provide diagnosis and more accurate staging, location of tumor with its capability in providing the anatomical and physiological information synchronizes. Therefore PET/CT plays an important role in oncology.

Use of High-Resolution X-Ray Micro-Computed Tomography for the Analysis of Internal Structural Changes in Maize Infected with Fusarium verticillioides

X-ray micro-computed tomography (X-ray micro-CT) is a non-destructive, three-dimensional (3D) imaging and analysis technique for the investigation of internal structure of a large variety of materials, including agricultural produce. As a relatively new method in the field of food science, X-ray micro-CT has been applied successfully to obtain micro-structural information of foods undergoing different physical and chemical changes. In this study, high-resolution X-ray micro-CT was used for non-destructive analysis of the internal structure of maize kernels infected with Fusarium verticillioides. The major anatomical features of the maize kernel were identified based on their differences in X-ray attenuation, i.e. the germ, scutellum, vitreous and floury endosperm. Fungal infection caused changes in the internal structure of the kernels over time, which included a decrease in total kernel volume and an increase in total volume of void space, with more voids observed in the germ and floury endosperm regions. No significant (P > 0.05) difference was observed between the control and the infected kernels; it was apparent that the changes observed in the infected kernels were not solely as a result of fungal growth. The grey level histograms of the control and infected kernels shifted to the lower grey value intensity range over time indicating an increase in void space within the kernels. In the 3D images, the increase in total volume of void space with fungal progression was clearer and the effect of fungal damage on the internal structure was evident.

A novel protocol for resolving feldspar crystals in synchrotron X-ray microtomographic images of crystallized natural magmas and synthetic analogs

X-ray computed microtomography is a non-destructive imaging technique recognized in the geosciences as a powerful tool to investigate rock textures directly in three dimensions (3D) at the micrometer and sub-micrometer scale. The quantitative morphological and textural analysis of images requires segmentation and characterization of phases in the reconstructed volume based upon their gray levels (related to their relative X-ray attenuation) and/or morphological aspects. Often the differences in X-ray attenuation of some phases are so small that no contrast is observed in the reconstructed slices or, although the human eye can discern the differences between these phases, it is difficult, or sometimes impossible, to reliably segment and separately analyze these phases. Facing this challenge, we propose an experimental and computational procedure that allows the segmentation of phases with small density variations in geomaterials. By using an experimental protocol based on phase-contrast synchrotron X-ray microtomography combined with a customized 3D image processing procedure, we successfully segmented feldspar from the glassy matrix in both a natural volcanic sample and a synthetic analog. Our results demonstrate that crystallized natural volcanic rocks and synthetic analogs can be characterized by synchrotron X-ray phase-contrast microtomography and that phase-retrieval processing is an invaluable tool for the reconstruction of 3D multiphase textures.

Influence of the X-ray beam quality on the dose increment in CT with iodinated contrast medium.

In computed tomography (CT), the image contrast is given by the difference in X-ray attenuation in the various tissues of the patient and contrast media are used to enhance image contrast in anatomic regions characterized by similar attenuation coefficients. Aim of the present work is to enlarge the range of applicability of the method previously introduced for organ dosimetry in contrast-enhanced CT, by studying the effects of X-ray beam quality on the parameters of the model. Furthermore, an experimental method for the evaluation of the attenuation properties of iodinated solutions is proposed. Monte Carlo simulations of anthropomorphic phantoms were carried out to determine a bi-parametrical (a and b) analytical relationship between iodine concentration and dose increase in organs of interest as a function of the tube kilo-voltage peak potential (kVp) and filtration. Experimental measurements of increments in Hounsfield Units (HU) were conducted in several CT scanners, at all the kVp available, in order to determine the parameter γ which relates the HU increment with the iodine mass fraction. A cylindrical phantom that can be filled with iodine solutions provided with an axial housing for a pencil ionization chamber was designed and assembled in order to measure the attenuation properties of iodine solutions under irradiation of a CT scanner and to obtain a further validation of Monte Carlo simulations. The simulation-derived parameters of the model, a and b, are only slightly dependent upon the tube kilo-voltage peak potential and filtration, while such scanner-dependent features influence mainly the experimentally-derived γ parameter. Relative dose variations registered by the ionization chamber inside the iodine-filled cylindrical phantom decrease when the X-ray mean energy increases, and reaches about 50% for 10 mg/ml of iodine. The dosimetric method for contrast-enhanced CT can be applied to all CT scanners by adopting average simulative parameters and by carrying out a simple measurement with a series of iodine contrast solutions. The novel experimental methodology introduced can provide a direct measurement of iodine attenuation properties.

Hafnia (HfO2) nanoparticles as an X-ray contrast agent and mid-infrared biosensor.

The interaction of hafnium oxide (HfO2) nanoparticles (NPs) with X-ray and mid-infrared radiation was investigated to assess the potential as a multifunctional diagnostic probe for X-ray computed tomography (CT) and/or mid-infrared biosensing. HfO2 NPs of controlled size were prepared by a sol-gel process and surface functionalized with polyvinylpyrrolidone, resulting in relatively spherical and monodispersed NPs with a tunable mean diameter in the range of ∼7-31 nm. The X-ray attenuation of HfO2 NPs was measured over 0.5-50 mM concentration and compared with Au NPs and iodine, which are the most prominent X-ray contrast agents currently used in research and clinical diagnostic imaging, respectively. At clinical CT tube potentials >80 kVp, HfO2 NPs exhibited superior or similar X-ray contrast compared to Au NPs, while both exhibited significantly greater X-ray contrast compared to iodine, due to the favorable location of the k-shell absorption edge for hafnium and gold. Moreover, energy-dependent differences in X-ray attenuation enabled simultaneous quantitative molecular imaging of each agent using photon-counting spectral (multi-energy) CT. HfO2 NPs also exhibited a strong mid-infrared absorption in the Reststrahlen band from ∼250-800 cm(-1) and negative permittivity below 695 cm(-1), which can enable development of mid-infrared biosensors and contrast agents, leveraging surface enhanced mid-infrared and/or phonon polariton absorption.

Application of high resolution X-ray computed tomography to mineral deposit origin, evaluation, and processing

High resolution X-ray computed tomography (CT) is the industrial equivalent of medical CAT scanning and provides a mechanism for non-destructive studies of the three-dimensional nature of geological materials. HRXCT produces two-dimensional images (slices) that reveal the interior of an object as if it had been sliced open along the image plane for viewing. A CT image is generated by differences in X-ray attenuation that arise from differences in density and composition within the object. By acquiring a contiguous set of slices, volumetric data for all or part of a sample can be obtained, allowing three-dimensional inspection and measurement of features of interest.CT is particularly effective in the study of metallic ores that commonly contain minerals spanning the range of densities of natural materials. Available software can produce grain shape, size, and orientation data from the scanned volume, which can be particularly useful for oriented samples. CT is particularly useful for studies of gold and other precious metal-bearing minerals that typically have significant contrast even with common metallic mineral phases. CT precisely defines the in-situ location of mineral grains of interest within a sample, which then can be studied in conventional petrographic sections, and other forms of data collected, e.g. isotope or trace element geochemistry. Another area of application is fluid inclusions, which can be discerned even in opaque phases, and fluid and vapor volumes measured for sufficiently large occurrences.We summarize CT principles and review available instrumentation, as well as scanning and data reduction protocols that provide unique three-dimensional information for diverse ore types and applications in mineral deposits geology. CT applications for economic geology and other fields will continue to expand as instruments continue to evolve and as scanning protocols and applications are extended for more precise quantification of three-dimensional relationships, particularly for fine-grained particles and small fluid inclusions in larger volumes and for separation of minerals with limited contrast.

X-ray phase-contrast tomosynthesis for improved breast tissue discrimination

PurposeAttenuation-based tomosynthesis has proven to successfully resolve the glandular tissue overlap present in mammography. However, the ability of tomosynthesis to differentiate tumorous and glandular tissue remains limited, due to the small differences in X-ray attenuation in breast tissue. One possibility to overcome this limitation and to further increase the diagnostic value of tomosynthesis exams, is the application of recently developed grating-based phase-contrast methods, which provide complementary information on the phase shift and the local scattering power of the sample. In this study, we report on first phase-contrast breast tomosynthesis results of a mastectomy sample slice with an invasive ductal carcinoma. Material and methodsA slice of a mastectomy sample with histologically proven invasive ductal cancer was imaged at the synchrotron radiation source ESRF (Grenoble, France). We used a two-grating interferometer setup at the ninth fractional Talbot distance and with an X-ray energy of 23keV. In grating interferometry absorption, differential phase, and scattering images are recorded simultaneously. The tomosynthesis scan comprises 61 projections. Multimodal tomosynthesis results were reconstructed using a standard filtered back-projection approach. Our findings are supported by a comparison of tomographic views to histopathology. ResultsPhase-contrast tomosynthesis combines the advantage of improved soft-tissue discrimination in phase-contrast imaging with the ability of tomosynthesis to provide a third dimension so that improved feature visibility is not hampered by superposition artifacts. Our results indicate superior diagnostic value due to the depth resolution supplied in tomosynthesis imaging; a region of necrotic tissue that is obscured in a projection image can clearly be depicted in one single tomosynthesis slice. Compared to absorption tomosynthesis alone, soft tissue contrast is significantly enhanced in phase-contrast tomosynthesis views, where fibrous structures are clearly visible. ConclusionIn this article we present the first proof-of-principle grating-based phase-contrast tomosynthesis of a mastectomy sample section. A comparison of conventional attenuation with phase-contrast and dark-field tomosynthesis indicates that complementary information from three signals yields an increase in diagnostic value, which is verified in a comparison of our results to histological sections of the sample. As grating-based phase-contrast mammography efficiently works with conventional lab sources, our benchmark results indicate the potential benefit of translating phase-contrast tomosynthesis into a clinical setting.

An Analysis on Mammograms using KDA in Multi Transform Domain

a robust Computer Aided Diagnosis (CADx) system for mammograms analysis has been the challenging task for years. The slight difference in X-ray attenuation between normal and abnormal glandular tissues makes the mammogram diagnosis complicated. The proposed CAD system discriminates the abnormal severity of mammograms into normal-benign (non-cancerous, non-spreadable), normal- malign (cancerous) ans benign-,malign, using wavelet features combined with spectral domain. Classification is performed on 206 different mammogram images from Mias database using Kernel Discriminant Analysis (KDA). KDA affords a non-parametric statistical approach with parzen window density estimation to estimate density function from a given sample dataset. The study reveals that the optimal smoothing parameters are increasing functions of the sample size of the complementary classes, features used to classify and value of the bandwidth. KeywordsMammograms, KDA, Accuracy, MCC

Non-destructive characterisation of polymers and Al-alloys by polychromatic cone-beam phase contrast tomography

X-ray computed tomography (XCT) has become a very important tool for the non-destructive characterisation of materials. Continuous improvements in the quality and performance of X-ray tubes and detectors have led to cone-beam XCT systems that can now achieve spatial resolutions down to 1 {mu}m and even below. Since not only the amplitude but also the phase of an X-ray beam is altered while passing through an object, phase contrast effects can occur even for polychromatic sources when the spatial coherence due to a small focal spot size is high enough. This can lead to significant improvements over conventional attenuation-based X-ray computed tomography. Phase contrast can increase by edge enhancement the visibility of small structures and of features which are only slightly different in attenuation. We report on the possibilities of polychromatic cone-beam phase contrast tomography for non-destructive characterisation of materials. A carbon fibre-reinforced polymer and the Al-alloys AlMg5Si7 and AlSi18 were investigated with high resolution cone-beam X-ray computed tomography with a polychromatic tube source. Under certain conditions strong phase contrast resulting in an upward and downward overshooting of the grey values across edges was observed. The phase effects are much stronger for the polymer than for the Al-alloys. The influencemore » on the phase contrast of the parameters, including source-detector distance, focal spot size and tube acceleration voltage is presented. Maximum phase contrast was observed for a maximum distance between the source and the detector, for a low voltage and a minimum focal spot size at the X-ray source. The detectability of the different phases is improved by the edge enhancement and the resulting improvement of sharpness. Thus, a better segmentation of the carbon fibres in the fibre-reinforced polymer and of the Mg{sub 2}Si-phase in the AlMg5Si7-alloy is achieved. Primary and eutectic Si cannot be detected by attenuation-based X-ray computed tomography due to the small difference in X-ray attenuation between the Si and the Al-matrix in AlSi18. However, phase contrast effects lead to a significant detectability and the large primary Si particles become clearly visible in the tomograms of AlSi18. - Highlights: Black-Right-Pointing-Pointer Phase contrast increases with increasing distance object-detector and with decreasing U, X-ray spot. Black-Right-Pointing-Pointer The detectability of details is improved by the phase contrast. Black-Right-Pointing-Pointer For the carbon fibre-reinforced polymer the visibility of the carbon fibres is improved. Black-Right-Pointing-Pointer For AlMg5Si7 the detectability of the phases Fe-aluminides and Mg{sub 2}Si particles is improved. Black-Right-Pointing-Pointer For AlSi18 primary Si particles with a size > 50 {mu}m become detectable because of the phase contrast.« less