In the area of translational research, stent developers consult pathologists to obtain the best and most complete amount of data from implanted test devices in the most efficient manner. Through the use of micron-scale computed tomography along with post-fixation staining techniques in this study, full volumes of previously implanted stents have been analyzed in-situ in a non-destructive manner. The increased soft tissue contrast imparted by metal-containing stains allowed for a qualitative analysis of the vessel’s response to the implant with greater sensitivity and specificity while reducing beam-hardening artifact from stent struts. The developed staining techniques included iodine-potassium iodide, phosphomolybdic acid, and phosphotungstic acid, all of which bind to soft tissue and improve image quality through their ability to attenuate high energy X-rays. With these stains, the overall soft tissue contrast increased by up to 85 percent and contrast between medial and neointimal layers of the vessel increased by up to 22 percent. Beam hardening artifact was also reduced by up to 38 percent after staining. Acquiring data from the entirety of the stent and the surrounding tissue increased the quality of stent analysis in multiple ways. The three dimensional data enabled a comprehensive analysis of stent performance, lending information such as neointimal hyperplasia, percent stenosis, delineation of vessel wall layers, stent apposition, and stent fractures. By providing morphological data about stent deployment and host response, this method circumvents the need to make the more traditional histology slides for a morphometric analysis. These same data may also be applied to target regions of interest to ensure histology slides are cut from the optimal locations for a more in-depth analysis. The agents involved in such techniques are readily available in most pathology laboratories, are safe to work with, and allow for rapid processing of tissue. The ability to forego histology altogether or to highly focus what histology is performed on a vessel has the potential to hasten the development process of any coronary stent.

Corrosion is the most important mechanical integrity issues the petrochemical industry has to deal with. While significant research has been dedicated to studying corrosion, it is still the leading cause of pipeline failure in the oil and gas industry. Not only is it the main contributor to maintenance costs, but also it accounts for about 15-20% of releases from the petrochemical industry and 80% of pipeline leaks. Enormous costs are directed towards fixing corrosion in facilities across the globe every year. Corrosion has caused some of the worst incidents in the history of the industry and is still causing more incidents every year. This shows that the problem is still not clearly understood, and that the methods that are being used to control it are not sufficient. A number of methods to detect corrosion exist; however, each one of them has shortcomings that make them inapplicable in some conditions, or generally, not accurate enough. This work focuses on studying a new method to detect corrosion under insulation. This method needs to overcome at least some of the shortcomings shown by the commercial methods currently used. The main method considered in this project is X-ray computed tomography. The results from this work show that X-ray computed tomography is a promising technique for corrosion under insulation detection. Not only does it detect corrosion with high resolution, but it also does not require the insulation to be removed. It also detects both internal and external corrosion simultaneously. The second part of this research is focused on studying the behavior of erosion/corrosion through CFD. This would allow for determining the erosion/corrosion rate and when it would take place before it starts happening. Here, the operating conditions that led to erosion/corrosion (from the literature) are used on FLUENT to predict the flow hydrodynamic factors. The relationship between these factors and the rate of erosion/corrosion is studied. The results from this work show that along with the turbulence and wall shear stress, the dynamic pressure imposed by the flow on the walls also has a great effect on the erosion/corrosion rate.

Thesis (M.S.) --University of Texas Graduate School of Biomedical Sciences at San Antonio, 2008. / Vita. Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains viii, 88 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 62-66).

Dissertation (Ph.D.) --University of Texas Graduate School of Biomedical Sciences at San Antonio, 2008. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri-Columbia, 2005. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Vita. "December 2005" Includes bibliographical references.

Thesis (MSc (Radiography))--Cape Peninsula University of Technology, 2017. / Background: Metabolic syndrome (MetS) is a clustering of cardiovascular disease (CVD) risk factors which include abdominal obesity, hyperglycaemia, hyper-triglyceridaemia, low HDL-cholesterol and hypertension. This cluster of metabolic deviations is believed to be the primary driver of the double global epidemic of diabetes (DM) and CVD, conditions which account for much of the social and economic global burden of disease. Similar to the global trend, a high prevalence of MetS (62%) and type 2 Diabetes Mellitus (T2DM) (28.2%) has been reported for the South African mixed ancestry population, with CVD risk significantly higher in subjects with DM. The increase in MetS prevalence is driven by the obesity epidemic and anthropometric cut-off values to define MetS for this particular component of the disease has been reported to differ widely between different populations and ethnicities. Currently the waist circumference (WC) cut-off value for MetS diagnosis needs to be determined and validated per ethnic group as opposed to the previously used European derived cut-off values (Alberti et al., 2006; 2009). Validation of the WC cut-off value needs to be against one of the so called gold standards of central obesity measurement, such as Computer Tomography (CT). This technique can measure subcutaneous fat (SAT) and visceral fat (VAT) individually, which is important because VAT has been reported to be associated with MetS and CVD. The current study forms part of a large research group, investigating the prevalence and risk factors for MetS and T2DM in the South African mixed ancestry population.

The purpose of this study is to evaluate the past and recent literature in order to determine the role of pre-operative CT scans in chronic otitis media. We aim to find consensus on the diagnostic ability of CT imaging in various anatomical parts of the middle ear and mastoid, and how this knowledge can affect clinical and surgical management. In context of all literature, there has been mixed results when looking at the sensitivity and specificity of middle ear structures. There was favorable consensus for CT's diagnosis of erosion of the malleus-incus complex, lateral semicircular canal, the facial nerve canal, and presence of soft tissue in the middle ear cavity. There were mixed results with respect to the erosion of tegmen tympani, and sigmoid sinus. Lastly, there was an unfavorable consensus when looking at the erosion of the stapes, oval window, and round window. Various studies conclude that the information gained from CT regarding the condition of the mastoid and middle ear can influence both the type of surgical method used and the success rate by reducing the risk of complications and recurrence of disease. In many studies, the methodology and interpretation of the CT scans are not very well presented. This unfortunately disallows meta-analysis between studies as the number of uncontrolled variables is too large. In the future, we hope that more information is provided as to the method of interpretation as well as the type of CT scanner and dosage. This will allow for a more meaningful result when comparing sensitivities and specificities towards middle ear pathologies, and it will allow for better examination of image quality and usefulness in context of the risk of radiation. Many otologists make routine use pre-operative CT scans in cases of chronic otitis media while others are more selective. In order to reach a consensus, however, more research focused on specific the decision-making process of physicians.

A possibilidade de exploração das imagens oferecida pela tomografia computadorizada cone beam (TCCB) permite investigações mais detalhadas do paciente. Este estudo, empregando alguns destes recursos, se propôs a comparar medidas cefalométricas realizadas sobre telerradiografias convencionais e reconstruções de perfil total e unilaterais obtidas da TCCB. Análises cefalométricas de 30 pacientes foram realizadas por um examinador calibrado sobre as reconstruções da TCCB e as telerradiografias convencionais. A reprodutibilidade dos fatores cefalométricos foi investigada por meio do coeficiente de correlação intraclasse em cada imagem. O método de Bland-Altman foi utilizado para averiguar a performance diagnóstica de cada imagem em relação às medidas de cada fator cefalométrico. O coeficiente de correlação intraclasse evidenciou semelhança de reprodutibilidade entre os exames. Quando os valores dos fatores cefalométricos foram comparados, observou-se forte concordância diagnóstica entre as mensurações realizadas sobre telerradiografias convencionais e imagens reconstruídas por TCCB. Conclui-se que, em pacientes sem assimetrias faciais importantes, a telerradiografia convencional e as reconstruções total e unilaterais a partir da TCCB oferecem desempenho de reprodutibilidade e resultado de análise cefalométrica semelhantes. / The possibility to explore images afforded by the cone beam computer tomography (CBCT) technique allows investigating patients in more detail. The present study uses some of these resources to compare cephalometric measurements obtained from conventional cephalograms and total and half-skull synthesized cone beam computed tomography (CBCT) cephalograms. Cephalometric analyses of 30 clinically symmetric patients; were conducted by a calibrated examiner on conventional and CBCTsynthesized cephalograms. Reproducibility was investigated using the intraclass correlation coefficient. The Bland-Altman analysis was used to assess the agreement of the measurements from each factor obtained by conventional, total, right and left CBCT-synthesized cephalograms. The intraclass correlation coefficient revealed similar levels of reproducibility. When the measurements obtained from conventional and CBCT-synthesized cephalograms were compared, the Bland-Altman analysis showed a strong agreement between them. Half-skull CBCT-synthesized cephalograms offer the same diagnostic performance and equivalent reproducibility in terms of cephalometric analysis as observed in conventional and total CBCT-synthesized cephalograms.

Nephrolithiasis can be a painful problem due to presence of kidney stones. Kidney stone is among the common painful disorders of the urinary system. Various imaging modalities are used to diagnose patients with symptoms of renal or urinary tract disease such as plain kidney, ureter, bladder x-ray (KUB), intravenous pyelography (IVP), and computed tomography (CT). As a traditional three-dimensional (3D) nephrolithiasis and kidney stones detection technique, computed tomography (CT) provides detailed cross-sectional images as well as 3D structure of kidney from moving the x-ray beam in a circle around the body. However, the risk of CT scans of the kidney is relatively higher exposure to radiation which is more than regular x-rays. C-arm technique is a new x-ray imaging modality that uses 2D array detector and cone shaped x-ray beam to create 3D information about the scanned object. Both x-ray source and 2D array detector cells mounted on C-shaped wheeled structure (C-arm). A series of projection images are acquired by rotating the C-arm around the patient in along circular path with a single rotation. The characteristic structure of C-arm allows to provide wide variety of movements around the patient that helps to remain the patient stationary during scanning time. In this work, we investigated a C-arm technique to generate a series of tomographic images for nephrolithiasis and detection of kidney stones. C-arm tomographic technique (C-arm tomosynthesis) as a new three dimensional (3D) kidney imaging method that provides a series of two dimensional (2D) images along partial circular orbit over limited view angle. Our experiments were done with kidney phantom which formed from a pig kidney with two embedded kidney stones inside it and low radiation dosage. Radiation dose and scanning time needed for kidney imaging are all dramatically reduced due to the cone beam geometry and also to limitation of angular rotation. To demonstrate the capability of our C-arm tomosynthesis to generate 3D kidney information for kidney stone detection, two groups of tomographic image reconstruction algorithms were developed for C-arm tomosynthesis: direct algorithms such as filtered back projection (FBP) and iterative algorithms such as simultaneous algebraic reconstruction technique (SART), maximum likelihood expectation maximization (MLEM), ordered- subset maximum likelihood expectation maximization (OS-MLEM) and Pre-computed penalized likelihood reconstruction (PPL). Three reconstruction methods were investigated including: pixel-driven method (PDM), ray-driven method (RDM) and distance driven method (DDM). Each method differs in their efficiency of calculation accuracy per computing time. Preliminary results demonstrated the capability of proposed technique to generate volumetric data about the kidney for nephrolithiasis and kidney stone detection by using all investigated reconstruction algorithms. In spite of each algorithms differs in their strategies, embedded kidney stone can be clearly visualized in all reconstruction results. Computer simulation studies were also done on simulated phantom to evaluate the results for each reconstruction algorithm. To mimic kidney phantom, simulated phantom was simulated with two different size kidney stones. Dataset of projection images was collated by using a virtual C-arm tomosynthesis with geometric configuration similar to real technique. All investigated algorithms were used to reconstruct 3D information. Different of image quality functions were applied to evaluate the imaging system and the reconstruction algorithms. The results show the capability of C-arm tomosynthesis to generate 3D information of kidney structures and to identify the size and location of kidney stones with limited amount of radiation dose.