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Evaluation of the D-Spect system: region centric acquisition and tracer kinetics

Costa, Filipa Alexandra Pina Barrento da Costa
Fonte: Universidade de Lisboa Publicador: Universidade de Lisboa
Tipo: Dissertação de Mestrado
Publicado em //2012 ENG
Relevância na Pesquisa
27.29%
Tese de mestrado integrado em Engenharia Biomédica e Biofísica, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2012; A tomografia de emissão de fotão único, usualmente conhecido por SPECT (do inglês single photon emission computed tomography), é uma técnica de medicina nuclear que permite diagnosticar doenças derivadas de alterações a nível fisiológico e celular. De forma a obter uma imagem SPECT, um radioisótopo é administrado ao paciente e a distribuição dos fotões emitidos é detectada de forma a criar uma imagem 3D. SPECT é cada vez mais utilizado para estudos cardíacos, no entanto o sistema ainda tem alguma limitações, e como tal novos sistemas de SPECT mais focalizados para exames ao coração foram surgindo. Um novo equipamento que foi criado em 2006, denominado D-SPECT, foi desenvolvido com o objectivo de criar imagens de perfusão de miocárdio com melhor qualidade de imagem, permitindo diagnósticos mais precisos. D-SPECT, ao contrário do sistema SPECT convencional, é constituído por 9 detectores montados verticalmente, criando uma configuração curva, adaptando-se ao tórax de um individuo. Para além da geometria inovadora, D-SPECT permite também a selecção manual de uma região de interesse (RI)...

Phage HK022 Roi protein inhibits phage lytic growth in Escherichia coli integration host factor mutants.

Clerget, M; Boccard, F
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /07/1996 EN
Relevância na Pesquisa
27.37%
Temperate coliphage HK022 requires integration host factor (IHF) for lytic growth. The determinant responsible for this requirement was identified as a new gene (roi) located between genes P and Q. This gene encodes a DNA-binding protein (Roi) containing a helix-turn-helix motif. We have shown that Roi binds a site within its own gene that is closely linked to an IHF binding site. By gel retardation experiments, we have found that IHF binding stabilizes the interaction of Roi with its gene. We have isolated three independent phage mutants that are able to grow on an IHF- host. They carry different mutations scattered in the roi gene and specifying single amino-acid changes. The interactions of all three Roi mutant proteins with the Roi binding site differed from that of the wild type. Roi displays strong similarities, in its C-terminal half, to two putative DNA-binding proteins of bacteriophage P1: Ant1 and KilA. The mode of action of the Roi protein and the possibility that IHF is modulating the expression and/or the action of Roi are discussed.

Quantitative Accuracy of Penalized-Likelihood Reconstruction for ROI Activity Estimation

Fu, Lin; Stickel, Jennifer R.; Badawi, Ramsey D.; Qi, Jinyi
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/02/2009 EN
Relevância na Pesquisa
27.32%
Estimation of the tracer uptake in a region of interest (ROI) is an important task in emission tomography. ROI quantification is essential for measuring clinical factors such as tumor activity, growth rate, and the efficacy of therapeutic interventions. Accuracy of ROI quantification is significantly affected by image reconstruction algorithms. In penalized maximum-likelihood (PML) algorithm, the regularization parameter controls the resolution and noise tradeoff and, hence, affects ROI quantification. To obtain the optimum performance of ROI quantification, it is desirable to use a moderate regularization parameter to effectively suppress noise without introducing excessive bias. However, due to the non-linear and spatial-variant nature of PML reconstruction, choosing a proper regularization parameter is not an easy task. Our previous theoretical study [1] has shown that the bias-variance characteristic for ROI quantification task depends on the size and activity distribution of the ROI. In this work, we design physical phantom experiments to validate these predictions in a realistic situation. We found that the phantom data results match well the theoretical predictions. The good agreement between the phantom results and theoretical predictions shows that the theoretical expressions can be used to predict the accuracy of ROI activity quantification.

Region of Interest (ROI) Computed Tomography

Chityala, R.; Hoffmann, K. R.; Bednarek, D. R.; Rudin, S.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em //2004 EN
Relevância na Pesquisa
27.41%
High-resolution computed tomography (CT) reconstructions currently require either full field of view (FOV) exposure, resulting in high dose, or region of interest (ROI) exposure, resulting in artifacts. To obtain high-resolution 3D reconstruction of an ROI with minimal artifacts, we have developed a method involving a non-uniform ROI beam filter to reduce dose outside the ROI while acquiring the ROI at a higher dose. High-resolution, high-dose full-field projections of a phantom were obtained. ROIs in the images were selected and the low-dose data outside the ROI were simulated by adding various levels of noise to the projection data corresponding to a dose of 1/16 and 1/256 of the original dose. For an ROI of 30% FOV, artifacts in the reconstructed ROI were minimal for both dose reduction levels. For an ROI of 10% FOV, artifacts remained minimal only for the 1/16th dose case. The effect of the presence of a high contrast object outside the ROI was also studied. We found that the intensity of the artifacts increases with the contrast of the object, its size, and its distance from the axis of rotation. CT using an ROI filter provides a way to reconstruct an ROI with reduced integral dose and yet with minimal artifacts and improved spatial resolution.

Region of interest (ROI) computed tomography (CT): Comparison with full field of view (FFOV) and truncated CT for a human head phantom

Chityala, R.; Hoffmann, K. R.; Rudin, S.; Bednarek, D. R.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em //2005 EN
Relevância na Pesquisa
27.37%
Cone-beam CT reconstruction can be performed at lower integral dose, by using a non-uniform beam filter between the x-ray source and the patient to obtain good image quality within an ROI with minimal artifacts. To evaluate the method, a human head phantom was placed on a rotary stage. Cone-beam projection images of the phantom were obtained with and without an ROI filter (dose reduction factor ~7). A mapping function was established to equalize the intensity outside the ROI (to compensate for the attenuation by the filter) to the intensity inside by assuming that those features lying both inside and outside very close to the edge of the ROI are the same. Reconstructed images were obtained using equalized projection images for 2 cases: one in which the outside region was smoothed using an averaging filter and the other with no smoothing outside. In addition, a third case was simulated by calculating the average pixel value inside the ROI for each image and assigning this value to all pixels outside the ROI for that image. The images were then back projected using a Feldkamp algorithm. We found that the three cases yield results inside the ROI comparable to those obtained using FFOV projections. In addition, the ROI filter reconstruction with smoothing provides image information outside the ROI comparable to the FFOV reconstruction. CT using an ROI filter provides a means to reconstruct reliable 3D for a volume of interest with greatly reduced integral dose compared to FFOV projections and with minimal artifacts.

Dose reduction by moving a region of interest (ROI) beam attenuator to follow a moving object of interest

Panse, Ashish S.; Swetadri Vasan, S. N.; Jain, A.; Bednarek, D. R.; Rudin, S.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
27.32%
Region-of-interest (ROI) fluoroscopy takes advantage of the fact that most neurovascular interventional activity is performed in only a small portion of an x-ray imaging field of view (FOV). The ROI beam filter is an attenuating material that reduces patient dose in the area peripheral to the object of interest. This project explores a method of moving the beam-attenuator aperture with the object of interest such that it always remains in the ROI. In this study, the ROI attenuator, which reduces the dose by 80% in the peripheral region, is mounted on a linear stage placed near the x-ray tube. Fluoroscopy is performed using the Microangiographic Fluoroscope (MAF) which is a high-resolution, CCD-based x-ray detector. A stainless-steel stent is selected as the object of interest, and is moved across the FOV and localized using an object-detection algorithm available in the IMAQ Vision package of LabVIEW. The ROI is moved to follow the stent motion. The pixel intensities are equalized in both FOV regions and an adaptive temporal filter dependent on the motion of the object of interest is implemented inside the ROI. With a temporal filter weight of 5% for the current image in the peripheral region, the SNR measured is 47.8. The weights inside the ROI vary between 10% and 33% with a measured SNR of 57.9 and 35.3 when the object is stationary and moving...

Automated Segmentation of Mouse Brain Images Using Multi-Atlas Multi-ROI Deformation and Label Fusion

Nie, Jingxin; Shen, Dinggang
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/2013 EN
Relevância na Pesquisa
27.32%
We propose an automated multi-atlas and multi-ROI based segmentation method for both skull-stripping of mouse brain and the ROI-labeling of mouse brain structures from the three dimensional (3D) magnetic resonance images (MRI). Three main steps are involved in our method. First, a region of interest (ROI) guided warping algorithm is designed to register multi-atlas images to the subject space, by considering more on the matching of image contents around the ROI boundaries which are more important for ROI labeling. Then, a multi-atlas and multi-ROI based deformable segmentation method is adopted to refine the ROI labeling result by deforming each ROI surface via boundary recognizers (i.e., SVM classifiers) trained on local surface patches. Finally, a local-mutual-information (MI) based multi-label fusion technique is proposed for allowing the atlases with better local image similarity with the subject to have more contributions in label fusion. The experimental results show that our method works better than the conventional methods on both in vitro and in vivo mouse brain datasets.

Effects of ROI Placement on PET-Based Assessment of Tumor Response to Therapy

Sattarivand, Mike; Caldwell, Curtis; Poon, Ian; Soliman, Hany; Mah, Katherine
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
27.37%
Purpose. Quantitative PET response assessment during therapy requires regions of interest (ROI). Commonly, a fixed-size ROI is placed at the maximum uptake point in the pretreatment study. For intratreatment, the ROI is placed either at the maximum uptake point (ROIpeak) or at the same location as the pretreatment ROI (ROIsame). We have evaluated the effects of the ROI placement on response assessment. Methods. PET scans of 15 head and neck cancer patients were used to evaluate the effects of the two ROI methods on response assessment. Results. The average intratreatment ROIpeak uptake was 13.4% higher than the ROIsame uptake (range −14% to 38%). The average relative change in ROIpeak uptake was 7.9% lower than ROIsame uptake (range −5% to 36%), resulting in ambiguous tumour classification in 19% of the tumours. Conclusion. Quantitative PET response assessment using a fixed-size ROI is sensitive the ROI placement. The difference between ROIpeak and ROIsame could be substantial resulting in ambiguous response assessment. Although the fixed-size ROI is simple to implement, it is also prone to the limitations and should be used with caution. Clinical trial data are necessary to establish reliable thresholds for fixed-size ROI techniques and to evaluate their efficacy for response assessment.

Medical Image Watermarking Technique for Accurate Tamper Detection in ROI and Exact Recovery of ROI

Eswaraiah, R.; Sreenivasa Reddy, E.
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
27.39%
In telemedicine while transferring medical images tampers may be introduced. Before making any diagnostic decisions, the integrity of region of interest (ROI) of the received medical image must be verified to avoid misdiagnosis. In this paper, we propose a novel fragile block based medical image watermarking technique to avoid embedding distortion inside ROI, verify integrity of ROI, detect accurately the tampered blocks inside ROI, and recover the original ROI with zero loss. In this proposed method, the medical image is segmented into three sets of pixels: ROI pixels, region of noninterest (RONI) pixels, and border pixels. Then, authentication data and information of ROI are embedded in border pixels. Recovery data of ROI is embedded into RONI. Results of experiments conducted on a number of medical images reveal that the proposed method produces high quality watermarked medical images, identifies the presence of tampers inside ROI with 100% accuracy, and recovers the original ROI without any loss.

Factores condicionantes de la relación entre la cuota relativa de mercado y el ROI : evidencia empírica en el sector manufacturero español

Jorge Moreno, Justo de; Laborda Castillo, Leopoldo
Fonte: SERVILAB (Alcalá de Henares) Publicador: SERVILAB (Alcalá de Henares)
Tipo: Trabalho em Andamento Formato: application/pdf
SPA
Relevância na Pesquisa
37.29%
En este trabajo se sugiere la existencia de una relación en forma convexa entre el ROI (Return On Investment) y la cuota relativa de mercado (en adelante CM) para el conjunto de los sectores que conforman las empresas manufactureras españolas, a partir de los datos recopilados por la ESEE en el periodo comprendido entre 1993- 1998. Los resultados obtenidos parecen indicar que las empresas se encuentra en la zona creciente de la curva que define la relación entre el ROI y la CM. El 70% de las empresas de la muestra se encuentran en la zona positiva frente al 30% que están en la zona negativa. Esto podría sugerir que dadas las características de las empresas, estas necesitan de un período de recuperación amplio, de forma que inicialmente las empresas invierten en ganar cuota de mercado para posteriormente incrementar su rentabilidad. Los diferentes modelos planteados incorporan una serie de variables mediadoras que representan una serie de potenciales estratégicos susceptibles de condicionar la citada relación entre el ROI y la CM y que siguiendo a Johnson y Sholes (2000) pueden clasificarse en: fortalezas competitivas, atractivo del mercado, producción ajustada y prácticas de recursos humanos. Por último, el trabajo pretende incorporar una variable moderadora representada por el nivel tecnológico de las empresas a partir de la clasificación introducida por Segura et al. (1989)...

Viszerales Fett bei ehemaligen Frühgeborenen als Risikofaktor für eine Insulinresistenz; Visceral fat in former preterm born children as a risk factor for an insulin resistance

Raiser, Carsten Rudi
Fonte: Universität Tübingen Publicador: Universität Tübingen
Tipo: Dissertation; info:eu-repo/semantics/doctoralThesis
DE_DE
Relevância na Pesquisa
27.47%
Einführung Kinder die LBW (GG<2.500g) geboren wurden besitzen die Prädisposition, ein metabolisches Syndrom zu entwickeln. Eine Komponente besteht hierbei in einer v.a. viszeralen Adipostias, die als ursächlich für die Entwicklung einer Insulinresistenz angesehen wird. Wir untersuchten ehemalige Frühgeborene die alle ein GG< 2.500g hatten, mittels der dual-energy x-ray absorptiometry (DEXA) durch das Legen eines geeigneten ROI´s (region of interest) auf das Vorliegen von viszeralem Fett. Methoden Alle untersuchten Kinder waren Frühgeborene (23+- bis 34+-Schwangerschaftswoche). Zur indirekten Messung von viszeralem Fett mittels DEXA (DEXA Lunar) wurden – zum Vergleich untereinander – zwei ROI´s gelegt: ROI A von der Oberkante L2 bis zur Unterkante L4 und ROI B von der Oberkanter L2 bis zu einer gedachten Verbindungslinie der kranialsten Punkte der Cristae iliacae. Um den prozentualen Anteil des Fettgehalts in diesen ROI´s an der Gesamtfettmasse (FM) angeben zu können, wurde ein ROI-Index ( Fett in ROI / FM) gebildet. Alle durch DEXA gemessenen und daraus hervorgehenden Parameter sowie anthropometrische Maße wurden nach den Kriterien untersucht, ob die Kinder bei Geburt AGA oder SGA waren bzw. entsprechend Geburtsgewichtsgruppen (LBW/VLBW/ELBW). Für anthropometrische Parameter bei Geburt und bei der Nachuntersuchung sowie für Messungen von Hautfettfalten (über dem Trizeps...

Chausson dans l'ombre de Wagner? : de la genèse à la réception du Roi Arthus

Benoit-Otis, Marie-Hélène
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
FR
Relevância na Pesquisa
37.39%
Ce travail aborde l’aspect spécifiquement compositionnel du phénomène wagnérien en France dans les dernières décennies du XIXe siècle, par le biais d’une étude de cas centrée sur l’opéra Le Roi Arthus d’Ernest Chausson (1855-1899). Exceptionnellement bien documenté grâce à de nombreuses sources dont une bonne part sont inédites (brouillons et esquisses du livret et de la partition, correspondance, etc.), cet opéra composé de 1886 à 1895 et créé en 1903 au Théâtre de la Monnaie de Bruxelles offre en effet un aperçu privilégié de la relation complexe qu’entretiennent les compositeurs français de cette époque avec l’imposante figure de Wagner. La question de l’influence wagnérienne dans Le Roi Arthus est abordée ici dans le cadre d’une démarche appliquant, dans une perspective historique, la méthode sémiologique développée par Jean Molino et Jean-Jacques Nattiez. L’analyse de la genèse, de la version finale et de la réception de l’oeuvre au moment de sa création permet d’obtenir une vue d’ensemble inédite des rapports s’établissant entre l’opéra de Chausson et les drames lyriques de Wagner, en particulier Tristan und Isolde. Il en ressort que des premières esquisses à la création de l’opéra...

Catalogue des actes du dauphin Louis II devenu le roi de France Louis XI, relatifs à l'administration du Dauphiné . III , Supplément

Louis XI (roi de France ; 1423-1483)
Fonte: Impr. générale Publicador: Impr. générale
Tipo: Livre Formato: application/pdf
Publicado em //1911 FRE
Relevância na Pesquisa
36.88%

Desarrollo organizacional a partir de la implementación del modelo ROI de gestión productividad - Reingeniería organizacional integral -

Fonte: Universidad Autónoma de Occidente; Ingeniería Industrial Publicador: Universidad Autónoma de Occidente; Ingeniería Industrial
Tipo: Bachelor Thesis; Proyecto de Grado Formato: PDF
SPA
Relevância na Pesquisa
37.19%
Los efectos de la globalización y la macroeconomía en las empresas de la región, especialmente en las micro, pequeñas y medianas empresas, tales como la generación de unos mercados con condiciones competitivas altamente exigentes, obligan a que las compañías que quieran sobrevivir y ser exitosas, se fortalezcan en su estructura interna, manejen óptimos niveles de competitividad, conozcan sus operaciones y la información que estas generan, así como las nuevas tendencias y herramientas en materia de dirección y gestión empresarial; lo cual plantea la necesidad de una solución en materia de gestión de productividad que involucre la optimización de los aspectos fundamentales de la organización, la modernización administrativa y el fortalecimiento competitivo como factores críticos de desarrollo organizacional. La propuesta presentada se resume como el modelo ROI de Gestión de productividad “Reingeniería Organizacional Integral”, el cual es un compendio de las mejores prácticas, modelos gerenciales y sistemas de desempeño empresarial que actualmente marcan las pautas de operación en las empresas que van adaptándose a las cambiantes condiciones de sus correspondientes entornos. Sin embargo, no se trata de un modelo más de gestión o de un nuevo sistema de planeación...

Medición del desempeño : retorno sobre inversión, ROI; ingreso residual, IR; valor económico agregado, EVA; análisis comparado

Cuevas Villegas, Carlos Fernando
Fonte: Universidad Icesi; Facultad de Ciencias Administrativas y Económicas Publicador: Universidad Icesi; Facultad de Ciencias Administrativas y Económicas
Tipo: article; Artículo Formato: PDF; p. 13-22; Electrónico; application/pdf
SPA
Relevância na Pesquisa
37.02%
El artículo quiere a partir de un recuento crítico de los análisis tradicionales del ROI y del IR dar una mirada analítica a estos indicadores comparándolos entre sí, mirando su alcance e importancia reales, igualmente sus problemas conceptuales y limitaciones. Al final se introduce el EVA, como medida y filosofía, mirando lo novedoso de la misma y los aspectos comunescon el ROI y el IR.

Estimating the Accuracy of the Return on Investment (ROI) Performance Evaluations

Botchkarev, Alexei
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 07/04/2014
Relevância na Pesquisa
27.39%
Return on Investment (ROI) is one of the most popular performance measurement and evaluation metrics. ROI analysis (when applied correctly) is a powerful tool in comparing solutions and making informed decisions on the acquisitions of information systems. The ROI sensitivity to error is a natural thought, and common sense suggests that ROI evaluations cannot be absolutely accurate. However, literature review revealed that in most publications and analyst firms reports, this issue is just overlooked. On the one hand, the results of the ROI calculations are implied to be produced with a mathematical rigor, possibility of errors is not mentioned and amount of errors is not estimated. On the contrary, another approach claims ROI evaluations to be absolutely inaccurate because, in view of their authors, future benefits (especially, intangible) cannot be estimated within any reasonable boundaries. The purpose of this study is to provide a systematic research of the accuracy of the ROI evaluations in the context of the information systems implementations. The main contribution of the study is that this is the first systematic effort to evaluate ROI accuracy. Analytical expressions have been derived for estimating errors of the ROI evaluations. Results of the Monte Carlo simulation will help practitioners in making informed decisions based on explicitly stated factors influencing the ROI uncertainties. The results of this research are intended for researchers in information systems...

ROI Based Quality Access Control of Compressed Color Image using DWT via Lifting

Phadikar, Amit; Maity, Santi P.
Fonte: Universidade Autônoma de Barcelona Publicador: Universidade Autônoma de Barcelona
Tipo: Artigo de Revista Científica Formato: application/pdf
Publicado em //2009 ENG
Relevância na Pesquisa
37.19%
Region-of-Interest (ROI) in an image or video signal contains important information and may be used for access control at various qualities using multiresolution analysis (MRA). This paper proposes a novel quality access control method of compressed color image by modulating the coefficients of ROI at various levels. Data modulation causes visual degradation in the original image and plays the key role in access control through reversible process. The modulation information, in the form of a secret key, is embedded in non-ROI part of the chrominance blue (Cb) channel of the color image using quantization index modulation (QIM). Lifting based DWT, rather than conventional DWT, is used to decompose the original image in order to achieve two-fold advantages, namely (1) better flexibility and low loss in image quality due to QIM and (2) better decoding reliability that leads to better access control. Only the authorized users having the full knowledge of the secret key restore the full quality of ROI. Simulation results duly support this claims.

JPEG2000 ROI coding through component priority for digital mammography

Bartrina Rapesta, Joan; Serra Sagristà, Joan; Aulí Llinàs, Francesc
Fonte: Universidade Autônoma de Barcelona Publicador: Universidade Autônoma de Barcelona
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/submittedVersion Formato: application/pdf
Publicado em //2010 ENG
Relevância na Pesquisa
27.37%
Region Of Interest (ROI) coding is a prominent feature of some image coding systems aimed to prioritize specific areas of the image through the construction of a codestream that, decoded at increasing bit-rates, recovers the ROI first and with higher quality than the rest of the image. JPEG2000 is a wavelet-based coding system that is supported in the Digital Imaging and Communications in Medicine (DICOM) standard. Among other features, JPEG2000 provides lossy-to-lossless compression and ROI coding, which are especially relevant to the medical community. But, due to JPEG2000 supported ROI coding methods that guarantee lossless coding are not designed to achieve a high degree of accuracy to prioritize ROIs, they have not been incorporated in the medical community. - This paper introduces a ROI coding method that is able to prioritize multiple ROIs at different priorities, guaranteeing lossy-to-lossless coding. The proposed ROI Coding Through Component Prioritization (ROITCOP) method uses techniques of rate-distortion optimization combined with a simple yet effective strategy of ROI allocation that employs the multi-component support of JPEG2000 codestream. The main insight in ROITCOP is the allocation of each ROI to an component. Experimental results indicate that this ROI allocation strategy does not penalize coding performance whilst achieving an unprecedented degree of accuracy to delimit ROIs. - The proposed ROITCOP method maintains JPEG2000 compliance...

On-board Robotic Multi-pinhole SPECT System for Region-of-interest (ROI) Imaging

Yan, Susu
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2014
Relevância na Pesquisa
27.35%

On-board image guidance, such as cone-beam CT (CBCT) and kV/MV 2D imaging, is essential in many radiation therapy procedures, such as intensity modulated radiotherapy (IMRT) and stereotactic body radiation therapy (SBRT). These imaging techniques provide predominantly anatomical information for treatment planning and target localization. Recently, studies have shown that treatment planning based on functional and molecular information about the tumor and surrounding tissue could potentially improve the effectiveness of radiation therapy. However, current on-board imaging systems are limited in their functional and molecular imaging capability. Single Photon Emission Computed Tomography (SPECT) is a candidate to achieve on-board functional and molecular imaging. Traditional SPECT systems typically take 20 minutes or more for a scan, which is too long for on-board imaging. A robotic multi-pinhole SPECT system was proposed in this dissertation to provide shorter imaging time by using a robotic arm to maneuver the multi-pinhole SPECT system around the patient in position for radiation therapy.

A 49-pinhole collimated SPECT detector and its shielding were designed and simulated in this work using the computer-aided design (CAD) software. The trajectories of robotic arm about the patient...

Unified communications: The search for ROI through tomorrow’s business communication solutions

Puglia, Vincent
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
36.88%
The traditional workplace is evolving; the way in which businesses communicate today is different than it was in the past and yet is likely to change again in the future. The current state of the economy and globalization has forced every organization to review its future business plans and cut costs everywhere including communications. Organizations are seeking out technology in hopes of finding new ways to reduce their bottom-line communication costs. Today, many enterprise business infrastructures are comprised of separate networks - voice, data, and mobile - yet most of the time these networks never interact. The ability to link business applications from various networks with communications proves to be valuable and is known as convergence. Convergence is defined as the combining of one or more elements into one. Unified Communications is a concept that looks to build on convergence, although it is not a new technology. Unified Communications is the term coined by the communications industry that signifies the comprehensive integration of various communication networks for reasons of increased revenue and reduced costs. Unified Communications will fundamentally transform the way in which people work - from decreased carrier costs to increased response times...