271 |
Pre-Clinical Evaluation of Biopolymer Delivered Circulating Angiogenic Cells in Hibernating MyocardiumGiordano, Céline 20 January 2012 (has links)
Vasculogenic cell-based therapy combined with tissue engineering is a promising revascularization strategy for patients with hibernating myocardium, a common clinical condition. We used a clinically relevant swine model of hibernating myocardium to examine the benefits of biopolymer-supported delivery of circulating angiogenic cells (CACs) in this context.
Twenty-five swine underwent placement of an ameroid constrictor on the left circumflex artery (LCx). After 2 weeks, positron emission tomography measures of myocardial blood flow (MBF) and myocardial flow reserve (MFR) were reduced in the affected region (both p<0.001). Hibernation (mismatch) was specific to the LCx territory. Swine were randomized to receive intramyocardial injections of PBS control (n=10), CACs (n=8), or CACs + a collagen-based matrix (n=7). At follow-up, stress MBF and MFR were increased only in the cells+matrix group (p<0.01), and mismatch was lower in the cells+matrix treated animals (p=0.02) compared to controls. Similar results were found using microsphere-measured MBF. Wall motion abnormalities and ejection fraction improved only in the cells+matrix group.
This preclinical swine model demonstrated ischemia and hibernation, which was improved by the combined delivery of CACs and a collagen-based matrix. To our knowledge, this is the first demonstration of the mechanisms and effects of combining progenitor cells and biopolymers in the setting of myocardial hibernation, a common clinical condition in patients with advanced coronary artery disease.
|
272 |
Utveckling av modulbaserad 11C-processutrustning inom PET : Presentation av idéer och koncept / Development of module-based 11C process equipment within PET : Presentation of ideas and conceptsFredén, Emil, Johansson, Sebastian January 2010 (has links)
This report describes the planning and the accomplishment of the final diploma workat the study program Mechanical Engineering, Department of Engineering Sciences, Uppsala University. Two students carried out the diploma work at GE HealthcareHusbyborg in Uppsala. The aim of the diploma work was to develop and improve existing processequipment for 11C-radiochemistry in PET. The process equipment was to be dividedinto smaller independent modules to make it more flexible. Part of the existingprocess equipment is an oven that is supposed to perform a specific chemicalreaction. One of the main goals was to study and improve this oven. The work could be divided into three main phases: 1.Present concepts for one module, and interface between different modules. 2. Analyze and choose components for the module mentioned above. 3. Present concepts for the oven, which is placed in the module mentioned above. At the beginning, user requirements were listed in cooperation with the mentor. Later, components available on the market and the existing process equipment wereanalyzed. A product function analysis of the oven was made to show its function and design. The concept phase was mainly about brainstorming to generate ideas. Later, hybridization was used as a method to combine different ideas. Then two prototypeswere built and tested. The test results showed which idea seemed to be the best.Different concepts were assessed and put into a concept selection matrix, after which the best was chosen and developed further.
|
273 |
Evaluation of the reconstruction algorithm, Ordered Subsets Expectation Maximization, in whole body Positron Emission TomographySvensson, Markus January 2008 (has links)
A Positive Electron Tomography/Computed Tomography devise was installed in theX-ray section at US Linköping in May 2007. Positive Electron Tomography examinations with 18F-fluoro-deoxy-glucose are mainly used for tumor examinations. During 2007 occurred approximately 200 examinations and in 2008 600 are planned. Today there are two reconstruction methods commercially available, Filtered Back projection and Maximum Likelihood Expectation Maximiza tion, used in the faster version called Ordered Subsets Expectation Maximization. The image quality in Positive Electron Tomography depends on the choice of reconstruction method and the settings of its parameters. We have performed a physical phantom study with Positive Electron Tomography to determine optimal parameters for the iterative reconstruction algorithm Ordered Subsets Expectation Maximization. To find out whether or not the quality of the image can be improved, so that the patient received radiation dose and/or examination time can be lowered. The phantom used was a NEMA IEC Body PhantomTM, designed to mimic smallhot lesions typical in 18F, Fluorine-18 PET, and all calculations were done according to the NEMA NU2-2001 protocol. The main conclusion from this project is that a higher level of contrast can be reached, compared to the one clinically obtained today. Using more iterations then recommended from the manufacturer. / I maj 2007 installerades en Positiv Elektron Tomografi /DatoriseradTomografi-kamera, PET/CT, i Röntgenavdelningen Linköping US. PET med 18F-fluoro-deoxy-glucose används huvudsakligen för tumörundersökningar.2007 genomfördes ca 200 undersökningar, och för 2008 är ytterligare 600 planerade. Idag finns två olika bildrekonstruktionsmetoder kliniskt tillgängliga; Filtered Back projection och Maximum Likelihood Expectation Maximization, där den vidareutvecklade versionen kallad Ordered Subsets Expectation Maximizationanvänds. Bildkvalitén från en Positive Electron Tomographykamera påverkas av valet av rekonstruktionsmetod och dess ingående parametrar. I detta projekt har en fantomstudie genomförts med syfte att bestämma de optimala parametrarna för den iterativa metoden Ordered Subsets Expectation Maximization. För att utreda huruvida stråldosen och/eller undersöknings tiden kan minskas. Det testfantom som användes var en NEMA IEC Body PhantomTM. Projektet följde metoden angiven i NEMA NU2-2001 protokollet. Det resultaten visar är att de rekommenderade inställningarna från tillverkaren inte är de optimala.
|
274 |
Optimization of iterative reconstruction methods for improving the contrast-to-noise ratio in PET examsSvensson, Markus January 2008 (has links)
A Positive Electron Tomography/Computed Tomography devise was installed in the X-ray section at US Linköping in May 2007. Positive Electron Tomography examinations with 18F-fluoro-deoxyglucose are mainly used for tumor examinations. During 2007 occurred approximately 200 examinations and in 2008 600 are planned.Today there are two reconstruction methods commercially available, Filtered Back projection and Maximum Likelihood Expectation Maximiza tion, used in the faster version called Ordered Subsets Expectation Maximization. The image quality in Positive Electron Tomography depends on the choice of reconstruction method and the settings of its parameters. We have performed a physical phantom study with Positive Electron Tomography to determine optimal parameters for the iterativereconstruction algorithm Ordered Subsets Expectation Maximization. To find out whether or not the quality of the image can be improved, so that the patient received radiation dose and/or examination time can be lowered. The phantom used was a NEMA IEC Body PhantomTM, designed to mimic small hot lesions typicalin 18F, Fluorine-18 PET, and all calculations were done according to the NEMA NU2-2001 protocol. The main conclusion from this project is that a higher level of contrastcan be reached, compared to the one clinically obtained today. Using more iterations then recommended from the manufacturer.
|
275 |
Structure-property relationships in copolyester fibers and composite fibersMa, Hongming 12 April 2004 (has links)
Polyethylene terephthalate is one of the most important engineering thermal plastics used for fibers, films and bottles. Despite its wide applications and vast global market, PET has shortcomings, which limits it usage in many
areas. PET has a glass transition temperature (Tg) of 80 DEGREE Celsius, this temperature
is too low for certain applications. Increase in glass transition temperature, high temperature mechanical properties, and dimensional stability is of great importance to further expand the applications of PET. Significant research efforts have been made toward this goal, using a variety of approaches.
In this work, we attempt to improve the properties of PET melt spun filament. Three strategies has been investigated (i) copolymerization of more rigid comonomer, 4, 4' bibenzoate unit into the PET structure, (ii) UV crosslinking of functionalized PET fiber, and (iii) Reinforcing PET matrix with carbon
nanofibers.
|
276 |
Dosimetry of Y-90 Liquid Brachytherapy in a Dog with Osteosarcoma Using PET/CTZhou, Jingjie 2011 May 1900 (has links)
A novel Y-90 liquid brachytherapy strategy is currently being studied for the treatment of osteosarcoma using a preclinical translational model in dogs to assess its
potential efficacy and toxicity. In this study, dosimetry calculations are performed for Y-90 liquid brachytherapy in a dog with osteosarcoma using the Geant4 Monte
Carlo code. A total of 611.83 MBq Y-90 radiopharmaceutical is administered via direct injections, and the in vivo distribution of Y-90 is assessed using a time-of-flight (TOF) PET/CT scanner.
A patient-specific geometry is built using anatomical
data obtained from CT images. The material properties of tumor and surrounding tissues are calculated based on a CT number - electron density calibration. The Y-90 distribution is sampled in Geant4 from PET images using a collapsing 3-D rejection technique to determine the decay sites. Dose distributions in the tumor bed and surrounding tissues are calculated demonstrating significant heterogeneity with multiple hot spots at the injection sites. Dose volume histograms show about 33.9 percent of bone and tumor and 70.2 percent of bone marrow and trabecular bone receive a total dose over 200 Gy; about 3.2 percent of bone and tumor and 31.0 percent of bone marrow and trabecular bone receive a total dose of over 1000 Gy. Y-90 liquid brachytherapy has the potential to be used as an adjuvant therapy or for palliation purposes. Future work includes evaluation of pharmacokinetics of the Y-90 radiopharmaceutical, calibration of PET/CT scanners for the direct quantitative assessment of Y-90 activity concentration, and assessment of efficacy of the Y-90 liquid brachytherapy strategy.
|
277 |
The key successful factor research of pet industry --- to take dog market as an example.Lin, Chi-Shun 22 July 2004 (has links)
This research is to adopt the quality quest research method, interviewing through the depth and the sorting and researches of the pet industry related development process, regard core resource theories as the foundation, look for to be subjected to the management key of visiting the individual cases to succeed factor, to understand its competitive advantage to produce. In addition, also consult and deliberate now before pet industry characteristic and actual situation condition, try to induce and identify the key succeeds factor of the relation between control and management results performance.
This research is final to acquire as follows what time conclusion:
(1) Pet already camp key success the characteristic of the factor is affected by the core resource
(2) The key that this research have to pay success the factor account six, including:" Block advantage"," management type"," store atmosphere"," sell the thoroughfare choice"," enter the goods mode" and" executive profession degree".
(3) When various keys succeed the factor can reach the certain level, to conduct the good and bad of the results to have the influence of absolute, and the management results of the pet industry then expresses in four factors in" finance results"," earning satisfaction"," customer satisfaction" and" technique satisfaction".
|
278 |
A study on pet dog business's key success factors comparison between web-store and traditional store sale pathChen, Hsin-Hung 25 August 2003 (has links)
Abstract
This study is an exploratory study. It discusses the comparison of pet dog business sales paths about web-store and traditional store sale path. This study tries to find the suitable sales path of pet dog business.Through this study, we could find the pet dog business is thrived by the web-store in Internet. Due to some problems of safety trade and order in Internet, we suggest the pet dog business must combine the traditional store sales path and web-store to get more performance.
In the conclusion, if we can handle and control the following key successful factors, we will get more competition in the pet dog business:
1. The key successful factors of traditional store sales path: the price of the product (the price of dog), pre and after service, the dog health.
2. The key successful factors of web-store: the friendly website design and safety trade.
|
279 |
Optimization of In-Beam Positron Emission Tomography for Monitoring Heavy Ion Tumor TherapyCrespo, Paulo 31 March 2010 (has links) (PDF)
In-beam positron emission tomography (in-beam PET) is currently the only method for an in-situ monitoring of highly tumor-conformed charged hadron therapy. In such therapy, the clinical effect of deviations from treatment planning is highly minimized by implementing safety margins around the tumor and selecting proper beam portals. Nevertheless, in-beam PET is able to detect eventual, undesirable range deviations and anatomical modifications during fractionated irradiation, to verify the accuracy of the beam portal delivered and to provide the radiotherapist with an estimation of the difference in dosage if the treatment delivered differs from the planned one. In a first study within this work, a set of simulation and fully-3D reconstruction routines shows that minimizing the opening angle of a cylindrical camera is determinant for an optimum quality of the in-beam PET images. The study yields two favorite detector geometries: a closed ring or a dual-head tomograph with narrow gaps. The implementation of either detector geometry onto an isocentric, ion beam delivery (gantry) is feasible by mounting the PET scanner at the beam nozzle. The implementation of an in-beam PET scanner with the mentioned detector geometries at therapeutic sites with a fixed, horizontal beam line is also feasible. Nevertheless, knowing that previous in-beam PET research in Berkeley was abandoned due to detector activation (Bismuth Germanate, BGO), arising most probably from passive beam shaping contaminations, the proposed detector configurations had to be tested in-beam. For that, BGO was substituted with a state-of-the-art scintillator (lutetium oxyorthosilicate, LSO) and two position sensitive detectors were built. Each detector contains 32 pixels, consisting of LSO finger-like crystals coupled to avalanche photodiode arrays (APDA). In order to readout the two detectors operated in coincidence, either in standalone mode or at the GSI medical beam line, a multi-channel, zero-suppressing free, list mode data acquisition system was built.The APDA were chosen for scintillation detection instead of photomultiplier tubes (PMT) due to their higher compactness and magnetic field resistance. A magnetic field resistant detector is necessary if the in-beam PET scanner is operated close to the last beam bending magnet, due to its fringe magnetic field. This is the case at the isocentric, ion beam delivery planned for the dedicated, heavy ion hospital facility under construction in Heidelberg, Germany. In-beam imaging with the LSO/APDA detectors positioned at small target angles, both upbeam and downbeam from the target, was successful. This proves that the detectors provide a solution for the proposed next-generation, improved in-beam PET scanners. Further confirming this result are germanium-detector-based, spectroscopic gamma-ray measurements: no scintillator activation is observed in patient irradiation conditions. Although a closed ring or a dual-head tomograph with narrow gaps is expected to provide improved in-beam PET images, low count rates in in-beam PET represent a second problem to image quality. More importantly, new accelerator developments will further enhance this problem to the point of making impossible in-beam PET data taking if the present acquisition system is used. For these reasons, two random-suppression methods allowing to collect in-beam PET events even during particle extraction were tested. Image counts raised almost twofold. This proves that the methods and associated data acquisition technique provide a solution for next-generation, in-beam positron emission tomographs installed at synchrotron or cyclotron radiotherapy facilities.
|
280 |
Evaluation of the reconstruction algorithm, Ordered Subsets Expectation Maximization, in whole body Positron Emission TomographySvensson, Markus January 2008 (has links)
<p>A Positive Electron Tomography/Computed Tomography devise was installed in theX-ray section at US Linköping in May 2007. Positive Electron Tomography examinations with 18F-fluoro-deoxy-glucose are mainly used for tumor examinations. During 2007 occurred approximately 200 examinations and in 2008 600 are planned. Today there are two reconstruction methods commercially available, Filtered Back projection and Maximum Likelihood Expectation Maximiza tion, used in the faster version called Ordered Subsets Expectation Maximization. The image quality in Positive Electron Tomography depends on the choice of reconstruction method and the settings of its parameters. We have performed a physical phantom study with Positive Electron Tomography to determine optimal parameters for the iterative reconstruction algorithm Ordered Subsets Expectation Maximization. To find out whether or not the quality of the image can be improved, so that the patient received radiation dose and/or examination time can be lowered. The phantom used was a NEMA IEC Body PhantomTM, designed to mimic smallhot lesions typical in 18F, Fluorine-18 PET, and all calculations were done according to the NEMA NU2-2001 protocol.</p><p>The main conclusion from this project is that a higher level of contrast can be reached, compared to the one clinically obtained today. Using more iterations then recommended from the manufacturer.</p> / <p>I maj 2007 installerades en Positiv Elektron Tomografi /DatoriseradTomografi-kamera, PET/CT, i Röntgenavdelningen Linköping US. PET med 18F-fluoro-deoxy-glucose används huvudsakligen för tumörundersökningar.2007 genomfördes ca 200 undersökningar, och för 2008 är ytterligare 600 planerade. Idag finns två olika bildrekonstruktionsmetoder kliniskt tillgängliga; Filtered Back projection och Maximum Likelihood Expectation Maximization, där den vidareutvecklade versionen kallad Ordered Subsets Expectation Maximizationanvänds. Bildkvalitén från en Positive Electron Tomographykamera påverkas av valet av rekonstruktionsmetod och dess ingående parametrar.</p><p>I detta projekt har en fantomstudie genomförts med syfte att bestämma de optimala parametrarna för den iterativa metoden Ordered Subsets Expectation Maximization. För att utreda huruvida stråldosen och/eller undersöknings tiden kan minskas. Det testfantom som användes var en NEMA IEC Body PhantomTM. Projektet följde metoden angiven i NEMA NU2-2001 protokollet. Det resultaten visar är att de rekommenderade inställningarna från tillverkaren inte är de optimala.</p>
|
Page generated in 0.4287 seconds