Small-animal x-ray imaging is an important tool for medical research. The penetration power of x-rays makes it possible to investigate the 3D structure of small animals and other thick biological samples by computed tomography (CT). However, small-animal x-ray imaging often requires high resolution due to the small structures involved, and short exposure times due to sample movement. This constitutes a challenge, since these two properties require compact x-ray sources with parameters that are not widely available. In this Thesis we present the first application of liquid-metal-jet sources for small-animal imaging. This source concept was invented at KTH just over ten years ago. The use of a high-speed metal jet as electron-beam target, instead of a solid anode, enables higher x-ray flux while maintaining a small x-ray spot for high-resolution imaging. In the present work, a liquid-metal jet source with a higher-energy spectrum has been developed. It has stronger 24 keV radiation compared to previous sources, which makes it more suitable for imaging of small animals and other few-cm-thick objects, which require the higher penetration of 20-35 keV x-rays. We have applied the liquid-metal-jet x-ray sources for whole-body imaging of sacrificed mice and zebrafish. With high-resolution absorption-contrast CT we have visualized fine bone details of mice. We have also used phase contrast, a new method that can considerably improve imaging of, e.g., soft tissue, for demarcation of mm-sized tumors inside a full mouse and for mouse cartilage imaging. In zebrafish imaging, we have exploited the greatly enhanced contrast of phase-imaging to resolve single muscle fibers (and possibly even myofibrils) in whole zebrafish in a laboratory setting for the first time. The muscle structures have diameters in the 5-7 μm range and extremely low contrast, which makes them difficult to observe. With phase contrast, we have demonstrated low-dose and high-resolution angiography of mouse and rat organs and tissues ex vivo. We show detection of blood vessels with diameters below 10 μm with radiation doses compatible with living small animals, which is not possible with absorption contrast and iodinated contrast agents. In addition, we have investigated the vascular network of tumors in mouse ears and visualized the chaotic arrangement of newly-formed blood vessels. Finally, we present the first results from a new high-power liquid-metal-jet x-ray source prototype, operating at 10× the power of our previous sources, with the same x-ray spot size. This source constitutes an important step towards future in-vivo small-animal laboratory imaging with high resolution. / Röntgenavbildning av små försöksdjur är en viktig metod inom medicinsk forskning. Röntgenstrålar penetrerar material, vilket gör det möjligt att undersöka 3D-strukturen hos försöksdjur och andra tjocka biologiska prov med hjälp av datortomografi (CT). Tyvärr kräver smådjursavbildning ofta dels hög upplösning, eftersom de relevanta strukturerna är små, dels korta exponeringstider, eftersom objektet tenderar att röra sig. Detta är en utmaning, då båda egenskaperna kräver kompakta röntgenkällor med speciella egenskaper som inte är brett tillgängliga. I denna avhandling visar vi den första användningen av metallstråleröntgenkällor för avbildning av hela smådjur. Den här typen av röntgenkälla uppfanns vid KTH för drygt tio år sedan. Genom att låta elektronerna träffa en stråle av flytande metall, istället för en solid metallanod, kan vi generera mer röntgenstrålning men samtidigt behålla en liten källpunkt, vilket behövs för avbildning med hög upplösning. En ny metallstrålekälla utvecklades som en del av denna avhandling. Den ger ett röntgenspektrum med högre energier, vilket gör källan mer lämpad än tidigare källor för avbildning av små försöksdjur och andra centimetertjocka biologiska objekt. Vi har använt metallstrålekällor för att avbilda intakta, avlivade möss och zebrafiskar. Med högupplöst absorptions-CT har vi detekterat små bendetaljer inuti möss. Vi har även använt faskontrastavbildning, en ny metod som avsevärt kan förbättra avbildning av mjukvävnad, till att demarkera millimeterstora tumörer inuti en hel mus, samt för avbildning av brosk i leder hos möss. Faskontrast ger en kraftig förstärkning av kontrasten i bilden, vilket även har använts för att för första gången detektera individuella muskelfibrer (och eventuellt även myofibriller) inuti zebrafiskar med en kompakt röntgenkälla. Muskelstrukturerna har diametrar på 5-7 μm och låg kontrast, vilket gör dem svåra att observera. Med hjälp av faskontrast har vi utvecklat en metod för att avbilda blodkärl med diametrar under 10 μm inuti organ och vävnader från möss och råttor ex vivo, med stråldoser som är kompatibla med studier av levande smådjur. Detta är inte möjligt med konventionell absorptionskontrast och jod-baserade kontrastmedel. Vi har dessutom avbildat nyformade blodkärl kring tumörer i musöron och observerat kärlens kaotiska struktur. Slutligen presenterar vi de första resultaten från en prototyp av en ny högeffektskälla. Källan har tio gånger högre effekt än tidigare metallstrålekällor, men bibehåller samma storlek på källpunkten. Den här högeffektskällan är ett viktigt steg mot framtida laboratoriebaserad avbildning av levande små försöksdjur med hög upplösning. / <p>QC 20150331</p>

Cortical bone is a dynamic tissue which undergoes adaptive and pathological changes throughout life. An improved understanding of the spatio-temporal process of remodeling holds great promise for improving our understanding of bone development, maintenance and senescence. The use of micro-computed tomography (µCT) on living animals is relatively new and allows the three dimensional quantification of change in trabecular bone microarchitecture over time. The use of in vivo µCT is limited by the radiation dose created by the x-ray beam, with commercially available in vivo systems generally operating in the 10-20 um resolution range and delivering an absorbed dose between 0.5-1 Gy. Because dose scales to the power of four with resolution, in vivo imaging of the cortical canal network, which requires a higher resolution, has not been achieved. I hypothesized that using synchrotron propagation phase contrast µCT, cortical porosity could be imaged in vivo in rats at a dose on the same level as those used currently for trabecular bone analysis. Using the BMIT-BM beamline, I determined the optimal propagation distance and used ion chamber and lithium fluoride crystal thermoluminescent dosimetry to measure the absorbed dose of my in vivo protocol as well as several ex vivo protocols using synchrotron phase contrast µCT at 5 µm, 10 µm, and 11.8 µm and conventional desktop in vivo protocols using commercial µCT systems. Using synchrotron propagation phase contrast µCT, I scanned the forelimb of two adult Sprague-Dawley rats and measured an absorbed dose of 2.53 Gy. Using two commercial µCT system, I measured doses between 1.2-3.6 Gy for protocols at 18µm that are in common use. This thesis represents the first in vivo imaging of rat cortical porosity and demonstrates that an 11.8 µm resolution is enough to visualize cortical porosity in rats, with a dose within the scope of those used for imaging trabecular bone in vivo.

Thesis (Ph. D.)--Materials science and engineering, Georgia Institute of Technology, 2005. / Stock, Stuart, Committee Chair ; Sanders, Thomas, Committee Member ; Snyder, Robert, Committee Member ; Johnson, Steven, Committee Member ; Wilkinson, Angus, Committee Member. Vita. Includes bibliographical references.

The inorganic chemistries of coal and petroleum differ because of their disparate geologic environments of formation, the physical state of the fuels, and the type and quantity of minerals and organic compounds in the fuels. Commercial coals typically contain 2 to 25% ash (average ~ 10%) while petroleums contain 0.003 to 0.07% ash (average ~ 0.01 %). Globally averaged, coal ash is dominated by Si, Fe, Ca, AI, and S, whereas petroleum ash contains significant quantities of V, Ni, S, Fe, Ca, Na, K, Mg, Si and AI. This larger number of important elements causes petroleum combustion slags to have more complex phase assemblages. The high vanadium contents of petroleum-based combustion feedstocks yield numerous crystalline V -oxides with stoichiometric amounts of Ca, Fe, Mg, AI, Ni andlor Na in the resulting slags. Slightly lower nickel contents yield abundant NiFe and Ni sulfides. The dominance of metals over silicon results in the formation of crystalline silicates following metal saturation of immiscible Si-rich glasses. High gasification temperatures (1200 - 1500°C) promote the development of equilibrial assemblages. Chemical variations between individual feedstock cokes coupled with nonuniform operational conditions result in three principal categories of petroleum coke slag; 1) sulfide dominant, 2) silica dominant, and 3) oxide dominant. Sulfide dominant slags are not necessarily derived from feedstocks with high sulfur contents, instead they appear to derive from feedstocks rich in chalcophile elements, predominantly Fe and Ni, by attracting sulfur otherwise lost by volatilization. Slagging additives can change the chemical categorization of resulting slags through phase modifications and the formation of new phases; this in tum can strongly alter the physical behavior of the slags. Compositionally diverse spinel oxides are the most common crystalline slag phase because of their wide thermal and compositional stability ranges, refractory nature, and rapid growth kinetics. Spinel compositions are strongly influenced by the inorganic chemistry of the feedstock, the composition of host phases, and the composition of additives. Coke slag spinels are generally enriched in AI, Fe, V, Mg, and Ni, and often contain Cr that is derived from reaction with refractory material. / Ph. D.

No description available.

X-ray computed tomography is a nondestructive method for 3D imaging of inner structure of objects; it is, however, restricted by absorption properties of materials. With phase contrast imaging, observation of samples with low absorption or with parts with similar absorption becomes possible. For a long time, phase contrast imaging has been restricted to synchrotron radiation sources or special techniques due to requirement of spatial coherence of radiation. Along with recent development of X-ray micro and nanofocus tubes and X-ray detectors a phase contrast imaging becomes available also with laboratory sources. In this work an overview of phase contrast imaging methods is given, with an emphassis on propagation based method. Examples of this method and application of phase retrieval algorithm on samples from RIGAKU Nano3DX and GE phoenix v|tome|x L240 stations within Laboratory of X-ray micro and nanotomography CEITEC BUT are shown.

Conventional phase-contrast imaging entails stepping an analyser grating across the detector to resolve the interference pattern caused by the x-rays after passing through a series of gratings in a so-called Talbot-Lau interferometer. However, the analyser grating in the interferometer poses a challenge, not only due to the machinery and alignment required but also due to each exposure delivering a dose to the subject. Another downside of the analyser grating is that whilst the phase-step length can be adjusted, the x-rays allowed through the grating depend on its slit-width ratio, which cannot be changed without changing the whole grating.This thesis evaluates if the analyser grating can be removed by instead using a deep silicon photon-counting detector which can determine the photon interaction position with an uncertainty of around one micrometre. It is concluded that such a high-resolution detector will not only be able to remove the need for an analyser grating and its associated challenges, but the results also imply a three-fold increase in the contrast-to-noise ratio when dose-matching the grating-based approach with the grating-less approach. Furthermore, the conventional absorption image, which is lost when using an analyser grating, will still be available using a high-resolution detector. Finally, the removal of the analyser grating shifts most of the system conditions to the source grating and the phase grating, making it possible to design a compact unit of the two gratings for integration into a CT scanner. / Konventionell faskontrast involverar att stega ett analysgitter över detektorn för att detektera interferensmönstret som skapas av röntgenstrålarna efter att de passerat genom en serie gitter i en så kallad Talbot-Lau interferometer. Analysgittret introducerar en utmaning, inte enbart på grund av maskineriet och kalibreringen som krävs, utan även då varje steg utsätter det röntgade föremålet för strålning. Ytterligare en begränsning är att även om längden på stegen kan justeras beror mängden röntgenstrålar som passerar genom analysgittret på gittrets slitsbredd, vilken inte går att ändra på utan att byta hela gittret.Den här uppsatsen utvärderar om analysgittret kan tas bort genom att istället använda en högupplöst fotonräknande djup kiseldetektor som har förmågan att uppskatta positionen av en fotoninteraktion inom en mikrometer. Slutsatsen är att en sådan detektor kommer att kunna ersätta analysgittret och resultaten tyder på en trefaldig ökning av contrast-to-noise ratio vid dosmatchning mellan metoden med analysgitter och metoden med en högupplöst detektor. Vidare behålls den konventionella absorptionsbilden då man använder en högupplöst detektor, någonting som annars går förlorat vid användandet av analysgittret. Slutligen skiftas de flesta villkoren på systemet till källgittret och fasgittret, vilket tyder på att en kompakt konstruktion av dessa två gitter skulle kunna integreras i en CT-skanner.

This thesis proposed and demonstrated a new all-polymer based fabrication process for an all-polymer flexible and parallel optical interconnect cable having a vertical light coupler, which can not only cut down the cost by eliminating metallization process for alignment but also facilitate both in production and application. Throughout the process, polyimide was used as the substrate, coated by Epoclad as claddings, then AP2210B and WPR 5100 were used to fabricate waveguides and 45 degree mirror couplers, respectively. In addition, precisely aligned mirror couplers to waveguides are fabricated by using polymer-based, non-metallic, and transparent alignment marks. Conventional and metallic alignment marks are easy to be detected by camera, when a layer of high reflective material, generally Cr metal, is patterned. However, transparent polymer material is used in this process, as alignment marks made of it which are actually buried phase structures. Therefore, it is hardly to be observed by conventional microscopy system. Hence, to increase the contrast of the alignment marks, I proposed and tested a feature specific alignment camera system for which the shape and depth of the alignment marks are optimized for phase-based imaging, such as phase contrast and Schlieren imaging. The results showed a contrast enhancement of alignment marks image compared to that of a conventional microscopy system. By using the fabrication and alignment process, process for adding waveguides to the structure is identified by using the polymer based alignment marks on the WPR 5100 layer. Mask was made by etch down process using fused silica wafer plate, Cr and AZ 3312 photoresist. At last, the developed and proposed process provides means of all-polymer based fabrication process for a flexible and parallel optical interconnect.

Neste trabalho, é proposto um esquema de cifragem e decifragem baseado em uma nova técnica de contraste de fase. Esta nova técnica, denominada \"técnica de contraste de fase de ordem zero\", transforma a modulação de fase para intensidade sem a necessidade de uma placa de alteração de fase (dot dielétrico de fase) no plano de Fourier de um correlator óptico 4f. Um processo de codificação, que não utiliza qualquer cálculo iterativo, é aplicado diretamente em uma imagem em níveis de cinza para gerar uma distribuição de fase. Em seguida, um processo de cifragem é realizado através da multiplicação da distribuição de fase por uma distribuição de fase aleatória. A vantagem deste método é o fácil esquema para recuperar a informação em níveis de cinza a partir da máscara de fase decifrada. A máscara de fase cifrada e a chave do sistema foram implementadas em SLMs (Spatial Light Modulators) do tipo LCTV (Liquid Crystal TV). As formas de codificação da imagem em níveis de cinza para gerar as máscaras de fase também foram investigadas. Como resultado, foram implementados dois tipos de EODs (Elementos Ópticos Difrativos) de fase. Um deles funciona no modo de transmissão, o outro, no modo de reflexão. Resultados experimentais mostram a aplicação da técnica de contraste de fase de ordem zero na visualização da informação codificada, tanto em SLM quanto em EODs de fase, e na verificação de padrões cifrados. / In this work, an encryption and decryption scheme based on a new phase contrast technique is proposed. This new technique, called the zero order phase contrast technique, transforma the phase modulation to intensity without the necessity of a phase-changing plate (phase dielectric dot) on the Fourier plane of a 4f optical correlator. A codification process, which does not use any iterative calculation, is applied directly in a gray level image to generate a phase distribution. After this, an encryption process is applied multiplying the phase distribution by a random phase distribution. The advantage of this method is the easy scheme to recover the gray level information from the decryption phase mask. The encrypted phase mask and the key of the system were implemented on Spatial Light Modulators of the kind LCTV. The encoding ways were investigated to generate the phase masks from gray level image, by implementing two kinds of phase Diffractive Optical Elements, operating in transmission and reflection modes. Experimental results show the successfully application of the zero order phase contrast technique in the visualization of encoded information both in Spatial Light Modulators and in phase only Diffractive Optical Elements as well as in the verification of encrypted patterns.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2016-03-03T14:19:21Z No. of bitstreams: 2 Dissertação - Jonas Francisco Scopel - 2015.pdf: 1854226 bytes, checksum: 9d48662eb3f8662b36ce1a088c29ac1c (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-03-03T14:22:35Z (GMT) No. of bitstreams: 2 Dissertação - Jonas Francisco Scopel - 2015.pdf: 1854226 bytes, checksum: 9d48662eb3f8662b36ce1a088c29ac1c (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2016-03-03T14:22:35Z (GMT). No. of bitstreams: 2 Dissertação - Jonas Francisco Scopel - 2015.pdf: 1854226 bytes, checksum: 9d48662eb3f8662b36ce1a088c29ac1c (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-02-20 / Diagnostic imaging techniques play an important role in assessing the exact location, cause, and extent of a nerve lesion, thus allowing clinicians to diagnose and manage more effectively a variety of pathological conditions such as entrapment syndromes, traumatic injuries, and space-occupying lesions. Ultrasound and nuclear magnetic resonance imaging are becoming useful methods for this purpose, but they still lack spatial resolution. In this regard, recent phase contrast x-ray imaging experiments of peripheral nerve allowed the visualization of each nerve fiber surrounded by its myelin sheath as clearly as optical microscopy. In the present study, we attempted to produce high-resolution x-ray phase contrast images of a human sciatic nerve by using synchrotron radiation propagation-based imaging (PBI). The PBIs showed high contrast and high spatial resolution, allowing clear identification of each fascicle structure and surrounding connective tissue. The outstanding result is the detection of such structures by phase contrast x-ray tomography of a thick human sciatic nerve section. This may further enable the identification of diverse pathological patterns, such as Wallerian degeneration, inflammatory infiltration and amyloid deposits. To the best of our knowledge, this is the first successful phase contrast x-ray imaging experiment of a human peripheral nerve sample. Our long-term goal is to develop peripheral nerve imaging methods that could supersede biopsy procedures. / As técnicas de diagnóstico por imagem desempenham um importante papel na determinação da localização exata, causa, e extensão de lesões de nervos periféricos, permitindo que o diagnóstico e manejo sejam mais eficazes em uma série de condições patológicas, como síndromes de encarceramento, e lesões traumáticas e expansivas. A Ressonância Nuclear Magnética e a Ultrassonografia têm se mostrado úteis neste propósito, porém possuem resolução espacial relativamente baixa. Neste sentido, experimentos recentes utilizando Radiografia por Contraste de Fase permitiram observar fibras nervosas individuais recobertas por suas bainhas de mielina de forma tão detalhada quanto a microscopia óptica. No presente estudo, procuramos obter imagens de alta resolução de nervo ciático humano, utilizando método de Imagem Realçada por Refração. As imagens demonstraram alto contraste e resolução espacial, permitindo a identificação de cada fascículo nervoso e suas respectivas bainhas conjuntivas. Resultados promissores foram obtidos através de Tomografia por Contraste de Fase de um espesso fragmento de nervo ciático humano, onde tais estruturas foram igualmente identificadas. Tais resultados poderiam possibilitar a detecção de diversas alterações patológicas, como degeneração Walleriana, infiltrado inflamatório e depósitos de amiloide. Ao nosso conhecimento, este é o primeiro experimento bem sucedido de Imagem por Contraste de Fase de nervos periféricos humanos. Nosso objetivo a longo prazo é desenvolver métodos de diagnóstico por imagem que possam substituir procedimentos de biópsia.