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Desenvolvimento de phantom antropom?rfico cerebral para simula??o de atividade ICTAL e imterictal utilizando a metodologia pet com fl?or-18Silbermann, Karina Nique Franz 27 August 2018 (has links)
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Previous issue date: 2018-08-27 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / The equipment and processes used in nuclear medicine must be included in a quality control
program that includes a series of tests and calibrations following the frequency established by current standards, which are based on international institutions protocols. The capability of anthropomorphic simulators mimic realistic situations are widely appointed to gauge essential data that guarantee the quality in medical generating processes. The purpose of this study was developing a cerebral anthropomorphic phantom for image simulation of ictal activity in nuclear medicine with 18F, PET-CT. It was made in an industrial printer with SLS (Selective Laser Sintering) technology, 4mm thick, using nylon 12. The model was segmented from a magnetic resonance study of a 40-year-old female adult. Two 40 nm thickness metal (Ag) electrodes were inserted in the right frontal lobe region to simulate ictal activity. For the images acquisition, the phantom was filled with distillated water and the 18F radioisotope. The images were acquired in PET-CT equipment with specific protocol for tomographic and dynamic cerebral studies. Images from the simulator without the insertion of the electrodes were acquired as pattern (basal), also were acquired images from the simulator with the electrodes and without electric field application, and the simulator with electric field application. The images were compared through SUV maximum values and uptake index. The non-parametric Wilcoxon-Mann-Whitney test was used as statistic approach, considering the three image conditions as independent groups. There was significant difference amongst the groups, being p < 0,001 when compared the average SUV maximum values by slices in the situations: basal x with electric field, and basal x without electric field, p = 0,129 when compared situations with electric field x without electric field, suggesting that this difference is not significant. All the groups presented significant differences for the uptake indexes obtained, being p < 0,001 in the situations basal x with electric field and basal x without electric field. The TAC (time-activity-curve) curves were obtained in A PET-CT dynamic protocol to demonstrate the 18F uptake in time, in the conditions with electric field and without electric field. The images were subtracted through SISCOM, using the basal condition as reference. The values found for p (SUV and uptake index) are compatible. The SISCOM histograms demonstrate differences for the three image comparisons. Although there are gradual raise of 18F uptake in time obtained in TAC evaluation for both with and without electric field conditions, the highest uptake visualized was when the electric field is applied. The anthropomorphic phantom developed is capable of simulating compatible zones with ictal activity, however the material used as resin in the electrodes must be modified so that the product may be commercialized in the future. / Os equipamentos e processos utilizados em medicina nuclear devem estar inclu?dos em um programa de controle de qualidade, o que inclui uma s?rie de testes e calibra??es com periodicidade estabelecida pelas normas vigentes, baseadas nos protocolos de institui??es internacionais. Os simuladores antropom?rficos, pela sua capacidade de mimetizar situa??es real?sticas, s?o amplamente empregados para aferir dados essenciais que garantam a qualidade nos processos geradores de imagens m?dicas. O objetivo deste trabalho foi desenvolver um phantom antropom?rfico cerebral para simula??o de imagens de atividade ictal em medicina nuclear, utilizando metodologia PET com Fl?or-18 (18F). O phantom foi confeccionado em
impressora industrial com tecnologia SLS (Selective Laser Sintering), de espessura de 4 mm, utilizando como mat?ria prima nylon 12. O modelo foi segmentado a partir de um estudo de resson?ncia magn?tica de um adulto normal, do sexo feminino, com 40 anos. Para a simula??o de atividade ictal foram inseridos, na regi?o correspondente ao lobo frontal direito, dois eletrodos met?licos constitu?dos de filme fino de 40 nm de prata (Ag). Para a aquisi??o das imagens, o modelo foi preenchido com ?gua destilada e com o radiois?topo 18F. As
imagens foram adquiridas em equipamento de PET-CT com protocolo espec?fico para estudos cerebrais tomogr?fico e din?mico. Foram adquiridas imagens: (1) simulador sem a inser??o dos eletrodos (padr?o/basal), (2) simulador com eletrodos sem aplica??o de campo el?trico e (3) simulador com os eletrodos e aplica??o de campo el?trico. As imagens foram comparadas entre si atrav?s dos valores de SUV m?ximo e do ?ndice de capta??o. A abordagem estat?stica utilizada considerou as tr?s condi??es de imagens como grupos independentes e o teste n?o param?trico de Wilcoxon-Mann-Whitney foi aplicado. Houve diferen?a significativa entre os grupos, sendo o valor de p < 0,001 quando comparados os valores de m?dia de SUV m?ximo por corte nas situa??es basal x sem campo el?trico e basal x com campo el?trico. Na
compara??o sem campo el?trico x com campo el?trico, o valor de p = 0,129 indica que a
diferen?a entre os grupos n?o ? significativa. Quando avaliado o ?ndice de capta??o entre os
grupos, todas as condi??es apresentaram diferen?a significativa, sendo p < 0,001 para os
grupos basal x sem campo el?trico e basal x com campo el?trico, e p = 0,0123 na compara??o
sem campo el?trico x com campo el?trico. As curvas TAC (time-activity-curve) foram
adquiridas para demonstrar a capta??o de 18F no tempo, nas condi??es com campo el?trico e
sem campo el?trico, em estudo din?mico de PET-CT. As imagens foram subtra?das atrav?s da
metodologia SISCOM, utilizando a condi??o basal como refer?ncia. Os valores encontrados
para p, tanto para SUV como para ?ndice de capta??o, s?o compat?veis com os achados visualizados nas imagens obtidas. Os histogramas gerados com a metodologia SISCOM
demonstram que h? diferen?as entre as tr?s condi??es de imagem. As curvas TAC tra?adas
correspondem ao aumento gradativo da concentra??o 18F no tempo, embora exista este
aumento nas condi??es sem campo e com campo, obtivemos a maior concentra??o quando o
sistema est? sob efeito do campo el?trico. O phantom antropom?rfico desenvolvido ? capaz
de simular zonas an?logas ?s de imagens de atividade ictal, por?m o material utilizado como
resina nos eletrodos deve ser modificado para que o produto possa ser comercializado
futuramente.
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Caractérisation numérique de l'exposition électromagnétique des personnes en bandes HF et VHF / Numerical characterization of an electromagnetic exposure on humans in HF and VHF frequency bandsFrère, Jeanne 28 June 2017 (has links)
Dans les environnements militaires, et plus particulièrement dans le domaine terrestre, de nombreux systèmes radioélectriques HF (de 3 à 30 MHz), VHF (de 30 à 300 MHz) et UHF (de 300 à 3000 MHz) sont utilisés. Ces systèmes remplissent plusieurs fonctions (communication longue et courte distance, brouillage, radar, etc ...) et peuvent parfois cohabiter sur un même porteur. Ces différentes fonctions utilisent plusieurs antennes et augmentent les risques de surexposition électromagnétique des opérateurs. Des normes civiles et militaires proposent des limites sur les champs électromagnétiques appliqués et sur des grandeurs dosimétriques (débit d'absorption spécifique DAS, densité de courant et champs électriques internes) pour limiter ces risques entre 0 et 300 GHz. Ces travaux de thèse ont deux objectifs principaux. Le premier est d'étudier les normes civiles et militaires afin de comprendre comment elles ont été développées et si elles sont réellement adaptées aux fréquences HF et VHF. Le deuxième est de proposer et valider une nouvelle méthode de validation des produits radio Thales. Pour cela, nous caractérisons numériquement le comportement électromagnétique et thermique du corps humain lors d'une exposition électromagnétique en bandes HF et VHF. L'étude des couplages entre le corps et les champs électromagnétiques externes nous permet de proposer pour la première fois des formules calculant les DAS dans le corps d'un fantôme homogène à partir, soit des courants induits le long du corps pour une exposition quelconque, soit du champ électrique appliqué pour une exposition en onde plane. / In military environments, especially land field, high frequencies (HF, 3 - 30 MHz), very high frequencies (VHF, 30 - 300 MHz) and ultra high frequencies (UHF, 300 - 3000 MHz) have been used for long range and shortrange communications, for communication interference or for detection. To have all those functions on the same carrier, they require many antennas, therefore they are increasing the operator's electromagnetic overexposure risk. Civilian and military standards were published providing limits on external electromagnetic fields and dosimetric quantities (specific absortion rate SAR, current density and internal electric field) to limit this overexposure risk between 0 and 300 GHz. The PhD thesis project has two main objectives. First, civilian and military standards are studied to understand how they were developed and if they are really suited for HF and VHF frequencies. Second, a new validation method of Thales radio product is proposed and validated. This PhD thesis project have characterized numerically the human body electromagnetic and thermal behavior during electromagnetic exposure in HF and VHF. Then, by studying couplings between external electromagnetic fields, induced current and human body, formulas to calculate both whole-body averaged SAR and local SAR 10 g in homogeneous body are proposed for the first time.
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Optimization and validation of a new 3D-US imaging robot to detect, localize and quantify lower limb arterial stenosesJanvier, Marie-Ange 10 1900 (has links)
L’athérosclérose est une maladie qui cause, par l’accumulation de plaques lipidiques, le durcissement de la paroi des artères et le rétrécissement de la lumière. Ces lésions sont généralement localisées sur les segments artériels coronariens, carotidiens, aortiques, rénaux, digestifs et périphériques. En ce qui concerne l’atteinte périphérique, celle des membres inférieurs est particulièrement fréquente. En effet, la sévérité de ces lésions artérielles est souvent évaluée par le degré d’une sténose (réduction >50 % du diamètre de la lumière) en angiographie, imagerie par résonnance magnétique (IRM), tomodensitométrie ou échographie. Cependant, pour planifier une intervention chirurgicale, une représentation géométrique artérielle 3D est notamment préférable. Les méthodes d’imagerie par coupe (IRM et tomodensitométrie) sont très performantes pour générer une imagerie tridimensionnelle de bonne qualité mais leurs utilisations sont dispendieuses et invasives pour les patients.
L’échographie 3D peut constituer une avenue très prometteuse en imagerie pour la localisation et la quantification des sténoses. Cette modalité d’imagerie offre des avantages distincts tels la commodité, des coûts peu élevés pour un diagnostic non invasif (sans irradiation ni agent de contraste néphrotoxique) et aussi l’option d’analyse en Doppler pour quantifier le flux sanguin. Étant donné que les robots médicaux ont déjà été utilisés avec succès en chirurgie et en orthopédie, notre équipe a conçu un nouveau système robotique d’échographie 3D pour détecter et quantifier les sténoses des membres inférieurs. Avec cette nouvelle technologie, un radiologue fait l’apprentissage manuel au robot d’un balayage échographique du vaisseau concerné. Par la suite, le robot répète à très haute précision la trajectoire apprise, contrôle simultanément le processus d’acquisition d’images échographiques à un pas d’échantillonnage constant et conserve de façon sécuritaire la force appliquée par la sonde sur la peau du patient. Par conséquent, la reconstruction d’une géométrie artérielle 3D des membres inférieurs à partir de ce système pourrait permettre une localisation et une quantification des sténoses à très grande fiabilité. L’objectif de ce projet de recherche consistait donc à valider et optimiser ce système robotisé d’imagerie échographique 3D.
La fiabilité d’une géométrie reconstruite en 3D à partir d’un système référentiel robotique dépend beaucoup de la précision du positionnement et de la procédure de calibration. De ce fait, la précision pour le positionnement du bras robotique fut évaluée à travers son espace de travail avec un fantôme spécialement conçu pour simuler la configuration des artères des membres inférieurs (article 1 - chapitre 3). De plus, un fantôme de fils croisés en forme de Z a été conçu pour assurer une calibration précise du système robotique (article 2 - chapitre 4). Ces méthodes optimales ont été utilisées pour valider le système pour l’application clinique et trouver la transformation qui convertit les coordonnées de l’image échographique 2D dans le référentiel cartésien du bras robotisé. À partir de ces résultats, tout objet balayé par le système robotique peut être caractérisé pour une reconstruction 3D adéquate.
Des fantômes vasculaires compatibles avec plusieurs modalités d’imagerie ont été utilisés pour simuler différentes représentations artérielles des membres inférieurs (article 2 - chapitre 4, article 3 - chapitre 5). La validation des géométries reconstruites a été effectuée à l`aide d`analyses comparatives. La précision pour localiser et quantifier les sténoses avec ce système robotisé d’imagerie échographique 3D a aussi été déterminée. Ces évaluations ont été réalisées in vivo pour percevoir le potentiel de l’utilisation d’un tel système en clinique (article 3- chapitre 5). / Atherosclerosis is a disease caused by the accumulation of lipid deposits inducing the remodeling and hardening of the vessel wall, which leads to a progressive narrowing of arteries. These lesions are generally located on the coronary, carotid, aortic, renal, digestive and peripheral arteries. With regards to peripheral vessels, lower limb arteries are frequently affected. The severity of arterial lesions are evaluated by the stenosis degree (reduction > 50.0 % of the lumen diameter) using angiography, magnetic resonance angiography (MRA), computed tomography (CT) and ultrasound (US). However, to plan a surgical therapeutic intervention, a 3D arterial geometric representation is notably preferable. Imaging methods such as MRA and CT are very efficient to generate a three-dimensional imaging of good quality even though their use is expensive and invasive for patients.
3D-ultrasound can be perceived as a promising avenue in imaging for the location and the quantification of stenoses. This non invasive, non allergic (i.e, nephrotoxic contrast agent) and non-radioactive imaging modality offers distinct advantages in convenience, low cost and also multiple diagnostic options to quantify blood flow in Doppler. Since medical robots already have been used with success in surgery and orthopedics, our team has conceived a new medical 3D-US robotic imaging system to localize and quantify arterial stenoses in lower limb vessels. With this new technology, a clinician manually teaches the robotic arm the scanning path. Then, the robotic arm repeats with high precision the taught trajectory and controls simultaneously the ultrasound image acquisition process at even sampling and preserves safely the force applied by the US probe. Consequently, the reconstruction of a lower limb arterial geometry in 3D with this system could allow the location and quantification of stenoses with high accuracy. The objective of this research project consisted in validating and optimizing this 3D-ultrasound imaging robotic system.
The reliability of a 3D reconstructed geometry obtained with 2D-US images captured with a robotic system depends considerably on the positioning accuracy and the calibration procedure. Thus, the positioning accuracy of the robotic arm was evaluated in the workspace with a lower limb-mimicking phantom design (article 1 - chapter 3). In addition, a Z-phantom was designed to assure a precise calibration of the robotic system. These optimal methods were used to validate the system for the clinical application and to find the transformation which converts image coordinates of a 2D-ultrasound image into the robotic arm referential. From these results, all objects scanned by the robotic system can be adequately reconstructed in 3D.
Multimodal imaging vascular phantoms of lower limb arteries were used to evaluate the accuracy of the 3D representations (article 2 - chapter 4, article 3 - chapter 5). The validation of the reconstructed geometry with this system was performed by comparing surface points with the manufacturing vascular phantom file surface points. The accuracy to localize and quantify stenoses with the 3D-ultrasound robotic imaging system was also determined. These same evaluations were analyzed in vivo to perceive the feasibility of the study.
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Assessing internal contamination after a radiological dispersion device event using a 2x2-inch sodium-iodide detectorDewji, Shaheen Azim 08 April 2009 (has links)
The detonation of a radiological dispersion device (RDD) may result in a situation where many individuals are exposed to contamination due to the inhalation of radioactive materials. Assessments of contamination may need to be performed by emergency response personnel in order to triage the potentially exposed public. The feasibility of using readily available standard 2x2-inch sodium-iodide detectors to determine the committed effective dose to a patient following the inhalation of a radionuclide has been investigated. The 2x2-NaI(Tl) detector was modeled using the Monte Carlo simulation code, MCNP-5, and was validated via a series of experimental benchmark measurements using a polymethyl methacrylate (PMMA) slab phantom. Such validation was essential in reproducing an accurate detector response. Upon verification of the detector model, six anthropomorphic phantoms, based on the MIRD-V phantoms, were modeled with nuclides distributed to simulate inhaled contamination. The nuclides assessed included Am-241, Co-60, Cs-137, I-131, and Ir-192. Detectors were placed at four positions on the phantoms: anterior right torso, posterior right torso, anterior neck, and lateral left thigh. The detected count-rate varied with respect to detector position, and the optimal detector location was determined on the body. The triage threshold for contamination was set at an action level of 250-mSv of intake. Time dependent biokinetic modeling was employed to determine the source distribution and activity in the body as a function of post-inhalation time. The detector response was determined as a function of count-rate per becquerel of activity at initial intake. This was converted to count-rate per 250-mSv intake for triage use by first responders operating the detector to facilitate triage decisions of contamination level. A set of procedure sheets for use by first responders was compiled for each of the phantoms and nuclides investigated.
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Preparação e caracterização de biomateriais poliméricos para avaliação da viabilidade de uso como phantom biológicoFerreira, Irisnei Luzia 19 May 2016 (has links)
Conselho Nacional de Desenvolvimento Científico e Tecnológico / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Fundação de Amparo a Pesquisa do Estado de Minas Gerais / Os desenvolvimentos teóricos e experimentais na área de biomateriais têm sido aplicados
diretamente a distintos campos da Medicina (odontologia, medicina regenerativa e radioterapia).
Esses avanços foram concentrados tanto para diagnosticar doenças como para a quantificação
de seus graus de progressão. Na perspectiva desses estudos, biomateriais estão sendo
projetados e confeccionados para aplicação em diversas áreas da ciência, proporcionado avanços
no radiodiagnóstico, na dosimetria para radioterapia e na calibração de equipamentos radioterápicos.
Desenvolver um phantom a partir de um biomaterial se tornou um grande aliado
da Medicina no tratamento de pacientes com doenças oncológicas, possibilitando melhor desempenho
dos equipamentos, com a finalidade de redução dos danos causados ao tecido sadio
devido ao excesso de exposição à radiação. Este trabalho utilizou polímeros: quitosana e gelatina
para confecção das estruturas poliméricas e foi possível controlar as diferentes formas de
produção e processamento, caracterizar e avaliar o biopolímero por técnicas físicas (ELT,MEV,
e DEI) e, por consequência, analisar a aplicabilidade como phantom pulmonar de camundongo.
Foi possível avaliar a morfologia dos biomateriais quantitativamente por microscopia eletrônica
de varredura associada a técnica de imagem. A relevância deste trabalho se concentra em desenvolver
um phantom a partir de biomateriais poliméricos que possa atuar como objeto simulador
fornecendo alto contraste de imagem quando submetido a análise. Dessa forma, a escolha da
técnica DEI foi satisfatória uma vez que trata-se de uma técnica de imagem de raios X de alta
resolução. As imagens obtidas por DEI têm mostrado os detalhes da microestrutura interna dos
biomateriais produzidos as quais possuem ≈ 10 μm de dimensão. Os phantoms confeccionados
apresentaram densidade variando de 0,08 a 0,13 g/cm3. / The theoretical and experimental developments in the biomaterials area have been directly
applied to different fields of Medicine (odontology, regenerative medicine and radiotherapy).
These advances have focused both for diagnosing diseases such as for quantifying degrees of
progression. From the perspective of these studies, biomaterials are being designed and manufactured
for application in various areas of science, provided advances in diagnostic radiology,
radiotherapy dosimetry and calibration of radiotherapy equipment. Develop a phantom from a
biomaterial has become a great ally of medicine in the treat patients with oncological diseases,
allowing better performance of the equipment in order to reduce damage to healthy tissue due to
excessive exposure to radiation. This work used polymers: chitosan and gelatin, for making the
polymeric structures and controlled for different types of production and processing, characterizing
and evaluating the biopolymer by physical techniques (STL, SEM and DEI) and therefore
analyze applicability as phantom mouse lung. It was possible to evaluate the morphology of biomaterials
quantitatively by scanning electron microscopy associated with imaging technique.
The relevance of this work focuses on developing a phantom from polymeric biomaterials that
can act as phantom providing high image contrast when subjected to analysis. Thus, the choice
of DEI technique is satisfactory since it is an imaging technique of X-ray high resolution. The
images obtained by DEI have shown the details of the internal microstructure of the biomaterial
produced which have ≈ 10 μm dimension. The phantoms had made density ranging from 0.08
a 0.13 g/cm3. / Tese (Doutorado)
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Estimativa da taxa de dose de radiação em tripulantes de aeronaves utilizando o método Monte CarloAlves, Matheus Carvalho 11 September 2017 (has links)
Aircraft crew members are exposed to cosmic rays of galactic and solar origin and secondary radiations produced due to interaction of primary cosmic rays with the atmosphere. Thus, it is necessary to estimate the dose that aircrew members receive and to evaluate the risks associated with their exposure. Radiation exposure scenarios were elaborated in computational scope in order to provide conversion coefficients (CCs) that relate measurable quantities (fluence) with limiting quantities (such as the effective dose). Knowing the particle fluence rate in a specific altitude, latitude and longitude, it is possible to determine the effective dose rate using these CC's. Aircraft crews are usually in sitting posture when exposed to cosmic radiation at altitudes of common flights. There are no studies in the literature using anthropomorphic phantoms in the sitting posture to calculate the effective dose rate at flight altitudes. In this study, effective dose per fluence conversion coefficients were calculated using the MCNPX code and the male and female UFH/NCI hybrid anthropomorphic phantoms in standing and sitting postures. Conversion coefficients were obtained in the isotropic irradiation geometry. CCs were calculated for neutrons, protons, photons, electrons, and positrons sources, which are the particles that most contribute to the dose at flight altitudes. The effective dose rate was calculated from the effective dose per fluence conversion coefficients and the fluence rate spectrum obtained by the EXPACS data package. The effective dose rate was also obtained using the fluence rate spectrum calculated by the MCNP6 software. The differences between the effective dose rate calculated for the phantom in the standing and sitting posture are less than 1%, showing that the posture does not contribute considerably to the dose of aircrew members. However, the dose rate calculated using the UFH/NCI phantom in the standing posture are 7 to 12 % higher than the dose rate obtained from the EXPACS package (which uses reference phantoms of ICRP 110) and are very close to experimental values of dose equivalent presented in other studies. Thus, the calculation of the effective dose rate using the UFH/NCI phantoms presents conservative results compared to those calculated using the ICRP reference phantoms and close to values obtained experimentally. The aim of this study was also estimate the dose to the fetus of pregnant crewmembers in a common flight. To estimate the dose to the fetus, CCs were calculated in the isotropic geometry for neutrons, protons, photons, electrons, positrons, and muons using a pregnant woman phantom and the MCNPX code. The dose rate was obtained from the conversion coefficients of equivalent dose per fluence and the fluence rate of cosmic radiation at an altitude of 12.3 km and under typical conditions of a flight from Vancouver to Frankfurt, whose average flight time is 9 hours. The results indicate that the equivalent dose to the fetus can exceeds the ICRP recommended fetal dose limit of 1 mSv after 6 or 7 round trips flights between Vancouver and Frankfurt. / Os tripulantes de aeronaves estão expostos a níveis elevados de radiação cósmica que tem origem galáctica, solar e de radiações secundárias produzidas devido à interação com a atmosfera. Assim, é necessário estimar a dose que estes indivíduos recebem e avaliar os riscos associados à sua exposição. Para isto, cenários de exposição à radiação foram elaborados em âmbito computacional a fim de fornecer coeficientes de conversão (CC’s) que relacionam grandezas mensuráveis (como a fluência) com grandezas limitantes (como a dose efetiva). Sabendo a taxa de fluência de partículas numa região onde um indivíduo é exposto, é possível determinar a taxa de dose efetiva usando estes CC’s. Tripulantes de aeronaves normalmente se encontram na postura sentada quando expostos à radiação cósmica em altitudes de voos convencionais. Como não foi encontrado na literatura estudos utilizando simuladores antropomórficos na postura sentada para o cálculo da taxa de dose efetiva em altitudes de voos tripulados, nesse trabalho, foram realizados cálculos de coeficientes de conversão de dose efetiva por fluência utilizando o código MCNPX e os simuladores antropomórficos híbridos UFH/NCI masculino e feminino nas posturas vertical e sentada e na geometria de irradiação isotrópica. Os CC’s foram calculados para as partículas que mais contribuem para a dose em altitude de voos tripulados, que são nêutrons, prótons, fótons, elétrons e pósitrons. A taxa de dose efetiva foi calculada a partir dos coeficientes de conversão de dose efetiva por fluência e do espectro da taxa de fluência obtidos pelo pacote de dados EXPACS. A taxa de dose efetiva também foi obtida utilizando os espectros de taxa de fluência calculados pelo software MCNP6. As diferenças entre a taxa de dose efetiva calculada para o simulador na postura vertical e sentada são menores do que 1 %, mostrando assim que a postura não influencia no cálculo da taxa de dose em tripulantes de aeronaves. Contudo, os valores da taxa de dose calculados utilizando o simulador UFH/NCI na postura vertical são de 7 a 12 % maiores do que os obtidos do pacote EXPACS (que utiliza os simuladores de referência da ICRP 110) e muito próximo a valores experimentais de equivalente de dose apresentados em outros trabalhos. Assim, o cálculo da taxa de dose efetiva a partir de CC’s usando os simuladores UFH/NCI apresenta resultados conservadores em relação aos calculados utilizando o simulador de referência da ICRP e próximo de valores obtidos experimentalmente. Outro objetivo desse trabalho foi estimar a dose no feto de tripulantes gestantes, considerando parâmetros de um voo real. Para estimar a dose no feto, foram calculados CC’s na geometria isotrópica para nêutrons, prótons, fótons, elétron, pósitrons e múons utilizando o simulador de mulher grávida e o código MCNPX. A taxa de dose foi obtida a partir dos coeficientes de conversão de dose equivalente por fluência e da taxa de fluência da radiação cósmica a uma altitude de 12,3 km e nas condições típicas de um voo de Vancouver a Frankfurt, que tem duração média de 9 horas. Os resultados mostram que a dose equivalente no feto ultrapassam o limite de 1 mSv, que é o limite de dose no feto durante a gestação considerado aceitável de acordo com a publicação 103 da ICRP, em até 7 voos de ida e volta entre Vancouver e Frankfurt. / São Cristóvão, SE
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Development and Testing of a Second Generation Hand-held Optical ImagerGonzalez, Jean 22 March 2012 (has links)
Hand-held optical imagers are developed towards clinical breast cancer imaging. Herein, a Gen-2 hand-held optical imager has been developed with unique features: (i) image curved breast tissues with ~86% surface contact, and (ii) perform reflectance and transillumination imaging using the novel forked probe heads. Extensive phantom studies were performed using 1% Liposyn solution (background, ~ 300 ml and 1000 ml volumes) and 0.45 cc India Ink (absorption) targets, under different target:background contrast ratios and target depths. Two-dimensional surface images detected target(s) up to 2.5 cm deep via reflectance imaging, and up to 5 cm deep via transillumination imaging. Preliminary studies on gel-based breast phantoms (~700 ml) detected targets via reflectance and transillumination imaging. Preliminary in-vivo reflectance studies on normal and cancerous breast tissues also detected targets, although with artifacts. In future, the portable Gen-2 imager has potential for clinical breast imaging via reflectance and transillumination approach after extensive in-vivo studies.
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Utvärdering av lägesosäkerheter i ortofoton framtagna med hjälp av DJI Phantom 4 RTK / Evaluation of position uncertainties in orthophotos developed with a DJI Phantom 4 RTKLarsson, Johan, Stark, Marcus January 2019 (has links)
Flygfotografering med Unmanned Aircraft System (UAS) är i jämförelse med traditionell fotogrammetri effektivare, billigare och säkrare vilket har medfört att denna teknik föredras av många aktörer. Ett tidskrävande arbete som varit svårt att kringgå är att etablera flygsignaler på marken som används för att georeferera och kontrollera flygbilderna med. Under 2018 presenterade UAS-tillverkaren DJI sin nya quadcopter med integrerad Real-Time Kinematic (RTK)-modul. I samband med detta kan kontinuerliga och noggranna positioner levereras via Nätverks-RTK (NRTK) och behovet av markstödpunkter reduceras. I denna studie undersöktes lägesosäkerheterna i plan för ortofoton som framställdes med hjälp av en DJI Phantom 4 RTK där flygbilderna georefererades med begränsat antal eller utan markstödpunkter. Lägesosäkerheterna beräknades och kontrollerades enligt Handbok i mät- och kartfrågor (HMK) – Ortofoto, vilket är ett stöddokument inom ämnet. Vid framställning av ett ortofoto krävs även en digital terrängmodell (DTM) eller en digital ytmodell (Digital Surface Model, DSM) och kvaliteten av denna har stor inverkan på ortofotots kvalitet. I denna studie kontrollerades och utvärderades därför en del av den DSM som användes vid ortofotoframställning för respektive uppsättning enligt den tekniska specifikationen SIS-TS 21144:2016. Resultatet från studien visar att ett ortofoto går att framställas utan markstödpunkter och samtidigt klara kraven på specificerad lägesosäkerhet enligt HMK-standardnivå 3. Den sammanlagda lägesosäkerheten beräknades till 0,029 m vilket är 5 mm högre i jämförelse med ett ortofoto som baserats på traditionell georefereringsmetod, dvs. med markstödpunkter. Kravet på kvalitet i höjddata uppfylldes också för ortofotoframställning trots att en systematisk effekt i höjd uppkom. Denna effekt påverkade inte ortofotots koordinater i plan då standardosäkerheterna i höjd var låga. Resultatet visade att om två markstödpunkter adderades i vardera änden av området, kunde de systematiska effekterna i höjd minimeras och det var då möjligt att skapa en DSM som uppfyller kraven för detaljprojektering (noggrannhetsklass 1–3) enligt SIS-TS 21144:2016. / Aerial photography with UAS is in comparison with traditional photogrammetry more efficient, cheaper and safer which has led to this technology being preferred by many performers. A time-consuming job that has been difficult to avoid is to establish signals at the ground that are used for georeferencing and evaluate the results. In 2018, the UAS manufacturer DJI presented its new quadcopter with integrated Real-Time Kinematic (RTK) module. This allows continuous and accurate positions delivered via Network RTK (NRTK) and the need of ground control points can be reduced. In this study, investigations of the position uncertainties in orthophotos produced using a DJI Phantom 4 RTK carried out where the aerial images were georeferenced with limited numbers or without ground control points. The position uncertainties were calculated and controlled according to the Swedish HMK – Ortofoto (Orthophoto) which is a document within the subject. When producing an orthophoto, a digital terrain model (DTM) or a digital surface model (DSM) is also required and the quality of this has a great impact on the result. Therefore, a part of the DSM used for orthophoto production for each set was checked and evaluated according to the Swedish technical specification, SIS-TS 21144:2016. The result of the study shows that an orthophoto can be produced without ground control points and at the same time meet the requirements for specified position uncertainty according to HMK standard level 3. The total position uncertainty was calculated to be 0,029 m, which is 5 mm higher compared to the orthophoto based on the traditional georeferencing method, i.e. with ground control points. The requirement for quality in height data was also met for orthophoto production even though a systematic effect in height occurred. This effect did not affect the plane coordinates in the orthophoto because of the low standard uncertainties in height. The result showed that if two ground control points were added at each end of the area, the systematic effects were minimized, and it was possible to produce a DSM that fulfils the requirements for accuracy class 1-3 according to SIS-TS 21144:2016.
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Nursing Management and Mirror Therapy for Phantom Limb PainHenry, Bridget 01 January 2016 (has links)
Phantom limb pain may occur after the accidental removal or surgical amputation of a limb. Phantom limb pain is the experience of pain in the limb that is no longer present. The clinical management of phantom limb pain is essential in the overall reduction of patient rehabilitation and poor patient outcomes. A patient’s degree of phantom limb pain is influenced by their personal response to loss and pain and can have devastating effects to a person’s social performance, occupational role, family role, relationships, and involvement in activities or hobbies. Like most chronic pain, phantom limb pain decreases the quality of life. Not all amputees who suffer from chronic pain respond to traditional therapies. The purpose of this integrated review of the literature was to explore current research and determine the efficacy of mirror therapy in the treatment of Phantom limb pain in amputees. A database search of CINAHL, PubMed (MEDLINE), and OneSearch was conducted. Mirror therapy had no reported side effects, was inexpensive, and was capable of being practiced at home and at the bedside. Relevant findings in the literature revealed a significant decrease in phantom limb pain when using mirror therapy for more than 4 weeks. Although limited research on the use of mirror therapy as an intervention for amputees, existing research supports the efficacy of mirror therapy for the management of phantom limb pain. Nurses and healthcare providers need education on mirror therapy to advocate for their patients to ensure the best possible outcome and reduction of phantom limb pain. Further research on mirror therapy is needed.
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Development of Clinically-Viable Applications of MR ElastographyFlewellen, James Lewis January 2008 (has links)
Magnetic Resonance Elastography is a method of imaging the elasticity of soft tissues through measurement of small motions induced into a sample. It shows great promise in the detection of a wide variety of pathologies, especially tumours.
An imaging protocol was developed to acquire MR elastography data for use in a clinical setting. A 3D gradient echo sequence was modified to allow for the detection of harmonic motion and tested on silicone phantoms and ex-vivo muscle and brain samples. The time for acquiring a high resolution, quantitative dataset of 3D motions was about 45 minutes. Our imaging method included motion encoding along all three coordinate axes and at several time points along the motion cycle. This time could be easily be reduced by more than half for future clinical use, while still retaining full quantitative data. A modified EPI sequence shows promise for even faster acquisition.
The ability to detect the mechanical anisotropy of brain and muscle tissue in ex-vivo samples was also investigated. Initial results from the muscle data indicate a change in shear wavelength is observed for actuation along orthogonal axes. This is a strong indicator of anisotropy detection. Further work needs to be done to improve results from the brain sample as preliminary results are inconclusive.
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