Submitted by Rafael Santana (rafael.silvasantana@ufpe.br) on 2018-02-01T19:25:01Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Dissertação Mestrado - Lorenna Santos.pdf: 3570385 bytes, checksum: af7a221e2cdc99daa203b7c07de4c948 (MD5) / Made available in DSpace on 2018-02-01T19:25:01Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Dissertação Mestrado - Lorenna Santos.pdf: 3570385 bytes, checksum: af7a221e2cdc99daa203b7c07de4c948 (MD5) Previous issue date: 2016-08-23 / FACEPE / O câncer de mama é um grande problema da saúde pública mundial. No Brasil, ele é responsável por cerca de 25% de novos casos de câncer a cada ano. Em 2016, espera-se aproximadamente 57.960 novos casos de câncer de mama no país. A principal ferramenta na redução da taxa de mortalidade por essa doença é o diagnóstico precoce. Apesar do uso bastante difundido da mamografia, ela apresenta algumas desvantagens em sua utilização como a exposição direta do paciente à radiação ionizante; a semelhança de densidade entre tecidos tumoral e normal; e a baixa reprodutibilidade em mamas de alta densidade. A tomografia por micro-ondas da mama é uma alternativa bastante promissora no auxílio ao diagnóstico de mama. Essa técnica de tomografia traz como vantagens, uma maior facilidade em diagnóstico precoce e de difícil localização, menor exposição da paciente; menor custo; e maior conforto à paciente. Faz-se necessário à produção de phantoms com características semelhantes ao tecido humano real, para o uso da tomografia por micro-ondas em mamas. O presente trabalho tem como objetivo principal a elaboração de um phantom de mama específico para tomografia em micro-ondas e sua caracterização através de simulações e medidas em sonda coaxial aberta. A metodologia e os materiais de escolha utilizados na confecção dos phantoms de estudo, foram retirados de pesquisas posteriores de autores reconhecidos na área. O HFSS foi o software de escolha para realização das simulações. Os resultados da simulação e as medidas experimentais dos phantoms na sonda coaxial foram compatíveis com os da literatura. Diante dos resultados, esperase que a caracterização dos phantoms da pesquisa contribua de forma positiva para a consolidação da técnica de tomografia por microondas e que a partir dessa pesquisa seja possível a elaboração de protocolos que facilitem a produção de phantoms para pesquisas posteriores. / Breast cancer is a major problem of public health worldwide. In Brazil, it is responsible for about 25% of new cases of cancer each year. In 2016, it is expected about 57,960 new cases of breast cancer in the country. The main tool in reducing the death rate from this disease is early diagnosis. Despite the widespread use of mammography, it has some disadvantages in its use as direct patient exposure to ionizing radiation; the similarity in density between tumor and the normal tissues; and low reproducibility in high-density breasts. The positron breast microwave is a very promising alternative to help diagnose breast cancer. This tomography technique has some advantages, greater ease in early diagnosis and difficult location, less exposure of the patient; lower cost; and greater comfort to the patient. It is necessary for the production of phantoms with similar characteristics to the actual human tissue, for the use of microwave tomography in breasts. This work has as main objective the development of a specific breast phantom tomography in microwave and characterization through simulations and measurements in open coaxial probe. The methodology and the choice of materials used in the manufacture of phantoms study were drawn from further research of authors recognized in the area. The HFSS was the software of choice to perform the simulations. The simulation results and experimental measurements of phantoms in coaxial probe were consistent with the literature. Given the results, it is expected that the characterization of the research phantoms contribute positively to the consolidation of microwave tomography technique and that from this research is the possible development of protocols that facilitate the production of phantoms for further research.

Made available in DSpace on 2014-10-09T12:46:09Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:44Z (GMT). No. of bitstreams: 0 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Foram elaborados e implementados testes de controle de qualidade em equipamentos de angiografia por subtração digital. Estes testes foram baseados em normas nacionais e internacionais e foram implementados em cinco equipamentos de três instituições diferentes. Estes testes avaliam os parâmetros de desempenho dos equipamentos e são utilizados para a determinação da taxa de kerma no ar na entrada da pele do paciente e do corpo clínico. Os testes foram realizados utilizando dispositivos, simuladores de pacientes e câmaras de ionização. Os testes convencionais e do sistema de subtração digital indicaram que os equipamentos avaliados encontravam-se em bom estado de desempenho. Os testes para verificação da taxa de kerma no ar indicaram que um dos equipamentos avaliados apresentou altas taxas de kerma no ar na entrada da pele do paciente em modo fluoroscopia. Este problema foi notificado, e as devidas providências foram imediatamente tomadas pela gerência do hospital. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP / FAPESP:99/06803-9

Made available in DSpace on 2014-10-09T12:52:02Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:44Z (GMT). No. of bitstreams: 0 / Tanto em Medicina Nuclear como em outras aplicações científicas as ferramentas para cálculos dosimétricos são de suma importância para atender os princípios básicos de proteção radiológica. Este trabalho desenvolve o manequim matemático da mulher brasileira, para ser usado como base em cálculos das Frações Absorvidas Específicas (FAEs) nos órgãos do corpo e no esqueleto, em virtude dos objetivos com relação à diagnose ou à terapia em Medicina Nuclear. O manequim ora desenvolvido é similar, na forma, ao manequim de Snyder tornando-o mais realístico para as condições antropomórficas da mulher brasileira. Para isso, utilizou-se o formalismo do método Monte Carlo, através do código computacional ALGAM-97®. Como contribuição aos objetivos deste trabalho, foi desenvolvido e implementado o sistema computacional cFAE – consulta Fração Absorvida Específica, que se torna mais versátil para a consulta do usuário pesquisador. A interface de diálogo com o operador foi projetada seguindo a atual tendência de utilização de uma linguagem orientada para o evento. Essa interface permite que o usuário navegue através dos manequins referência, escolha o órgão fonte, a energia desejada e receba as respostas num diálogo eficiente e intuitivo. O sistema fornece, além dos dados referentes à mulher brasileira, também aqueles referentes ao modelo de Snyder e ao modelo do homem brasileiro. O sistema possibilita não apenas introduzir os dados individuais para as FAEs dos três manequins, mas também a comparação entre eles. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2015-08-07T14:35:13Z No. of bitstreams: 0 / Made available in DSpace on 2015-08-07T14:35:13Z (GMT). No. of bitstreams: 0 / A braquiterapia de alta taxa de dose é uma das modalidades mais utilizadas em braquiterapia para o tratamento de câncer. Os diversos avanços tecnológicos, bem como a evolução das técnicas de tratamento tornaram a braquiterapia de alta taxa de dose uma das modalidades de estado da arte para o tratamento de alguns cânceres. Parte deste avanço é creditada à melhoria na acurácia e na prescrição de dose absorvida recomendada ao paciente, ao longo dos anos. Este avanço permite que atualmente seja possível realizar os cálculos dosimétricos, por meio de sistemas de planejamento computadorizado, considerando as heterogeneidades dos pacientes, tais como: tecidos e órgãos com composições diferentes da água (meio de referência em radioterapia), contorno do paciente individualizado, introdução de aplicadores, dentre outros. Tais avanços demandam o controle de qualidade destas ferramentas, com objetivo de assegurar que todo o processo de tratamento seja satisfatório e acurado. Até o momento, a comunidade carece de um sistema experimental capaz de avaliar, considerando os níveis de incerteza, se os sistemas de planejamento computadorizados são aptos a considerar a heterogeneidade dos tratamentos. Neste trabalho, apresentamos o desenvolvimento de medidas experimentais em um objeto simulador, com capacidade de mensurar as diferenças introduzidas pela heterogeneidade por meio de três técnicas dosimétricas experimentais: termoluminescência, filmes radiocrômicos e ionométrica. Os resultados experimentais foram comparados com as simulações de Monte Carlo e com um sistema de planejamento computadorizado comercial, apto a realizar correções de heterogeneidade em braquiterapia. Discutimos as principais etapas de desenvolvimento deste objeto simulador, seus resultados experimentais e as comparações com os demais sistemas. As conclusões e as etapas futuras deste projeto também são apresentadas. / Tese (Doutorado em Tecnologia Nuclear) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

To circumvent some inherent problems in the conventional ECG, this research reinvestigates an ‘unassisted’ approach which enables ECG measurement without the placement of leads on the body. Employed in this research is a widely accepted assumption that the electrical activity of the heart may be represented, largely, by a 3-D time-varying current dipole (3D-CD). From the PhysioBank database, mECG and fECG data were obtained, and Singular Value Decomposition (SVD) was performed to estimate the time-varying Vector ECG dipole. To determine the sensing matrix responsible for transforming the activity of the 3D-CD into the potential distribution on the surface of the medium, the ECG vector dipole signals are used to excite a 3D-CD in water medium of a specific shape-containing-ellipsoid model(s) in COMSOL tool. The sensing matrix thereby estimated is then utilized to reconstruct the 3D-CD signals from the signals measured by the probes on the surface of the medium. Fairly low NRMSEs (Normalized Root-Mean-Squared Errors) are attained. The approach is also successfully extended to the case of two ellipsoids, one inside the other, representing a pregnant female subject. Low NRMSEs (Normalized Root-Mean-Squared Errors) are again observed.

No description available.

Fat intra-body communication is a newly proven concept that is built on using human fat tissues as a communication channel for electromagnetic waves inside the body. This allows for two implanted external devices to connect through an intra-body closed-loop communication channel. This concept utilizes the fact that the fat tissues have low dielectric properties and are located between two tissue layers, skin and muscle, which have high dielectric permittivity and high loss tangent so that the signal propagates and confines with lower losses within the fat tissue. In this study, the eligibility of using monkey fat tissues as a communication channel for intra-body communication is being investigated. This comes as a first step in a long process of testing implementing medical devices, mainly prosthetic limbs, on non-human primates using fat-IBC at microwave frequencies. To be able to do that, an experimental characterization of ex-vivo monkey fat, skin, and muscle tissues to explore their dielectric properties compared to those of humans is being carried out. This study of the dielectric properties of monkey tissues is the first of its kind to be carried out on two samples of ex-vivo monkey tissues. Calf tissues have also been investigated in the study to get an insight on the potential differences between human and non-human body tissues in general before doing measurements on monkey tissues. For the measurements, an RF network analyzer and an open-ended coaxial probe method have been implemented. Phantoms that mimic the human tissues have been fabricated to be used as a reference point. The initial investigation demonstrates that calf fat tissues have much higher dielectric properties than human fat tissues. Monkey fat, muscle, and skin tissues showed many similarities to human tissues regarding their dielectric properties. This indicates that monkey tissues can be used for fat intra-body communication. Future numerical and analytical modeling of the monkey tissues needs to be conducted to confirm and strengthen this finding.

No description available.

La protonthérapie est une technique avancée de radiothérapie qui permet de délivrer une dose élevée à la tumeur, tout en épargnant au mieux les tissus sains environnants, grâce aux propriétés balistiques des protons. Cependant, des particules secondaires, principalement des neutrons, sont créées par les interactions nucléaires que les protons initient dans les composantes de la ligne et de la salle de traitement, ainsi que dans le patient. Ces neutrons secondaires conduisent à des doses indésirables déposées aux tissus sains situés à distance du volume cible, dont la conséquence pourrait être une augmentation du risque de développement de seconds cancers chez les patients traités et en particulier chez les enfants. Cette thèse a pour objectif d’évaluer par calcul les doses dues aux neutrons secondaires reçues par des patients de différents âges traités à l’Institut Curie- centre de protonthérapie d’Orsay (ICPO) par des faisceaux de protons de 178 MeV pour des tumeurs intracrâniennes. Les traitements sont réalisés dans la nouvelle salle de l’ICPO équipée d’un bras isocentrique IBA. Les composants de la ligne et de la salle de traitement ainsi que la source de protons ont été modélisés à l’aide du code de calcul Monte Carlo MCNPX. Le modèle obtenu a été validé par une série de comparaisons de calculs à des mesures expérimentales. Ces comparaisons ont concerné : a) les distributions de doses latérales et en profondeur du faisceau de protons primaire dans un fantôme d’eau, b) la spectrométrie des neutrons en une point de la salle, c) les équivalents de doses ambiants en différents points de la salle et d) les doses à distance du volume cible au sein d’un fantôme physique anthropomorhe. Des accords satisfaisants ont été obtenus entre les calculs et les mesures, permettant ainsi de considérer le modèle comme validé.Les fantômes hybrides-voxels de différents âges, développés par l’Université de Floride ont été ensuite introduits dans le modèle et des calculs de doses dues aux neutrons secondaires aux différents organes de ces fantômes ont été réalisés. Les doses diminuent lorsque la distance de l’organe au champ de traitement augmente et lorsque l’âge du patient augmente. Un patient de 1 an peut recevoir des doses deux fois plus élevées qu’un adulte. La dose maximale, égale à 16,5 mGy pour un traitement délivrant 54 Gy à la tumeur, est reçue, pour le fantôme de 1 an, par les glandes salivaires. Une incidence latérale (gauche ou droite) du faisceau de protons peut délivrer des doses deux fois plus élevées qu’une incidence supérieure (gauche ou droite), et quatre fois plus élevées qu’une incidence antéro-supérieure pour certains organes. Des doses équivalentes aux organes dues aux neutrons ont été aussi calculées. Les facteurs de pondération wR des neutrons varient entre 4 et 10, et les doses équivalentes atteignent au maximum 155 mSv au cours d’un traitement complet. / Proton therapy is an advanced radiation therapy technique that allows delivering high doses to the tumor while saving the healthy surrounding tissues due to the protons’ ballistic properties. However, secondary particles, especially neutrons, are created during protons’ nuclear reactions in the beam-line and the treatment room components, as well as inside the patient. Those secondary neutrons lead to unwanted dose deposition to the healthy tissues located at distance from the target, which may increase the secondary cancer risks to the patients, especially the pediatric ones. The aim of this work was to calculate the neutron secondary doses received by patients of different ages treated at the Institut Curie-centre de Protonthérapie d’Orsay (ICPO) for intracranial tumors, using a 178 MeV proton beam. The treatments are undertaken at the new ICPO room equipped with an IBA gantry. The treatment room and the beam-line components, as well as the proton source were modeled using the Monte Carlo code MCNPX. The obtained model was then validated by a series of comparisons between model calculations and experimental measurements. The comparisons concerned: a) depth and lateral proton dose distributions in a water phantom, b) neutron spectrometry at one position in the treatment room, c) ambient dose equivalents at different positions in the treatment room and d) secondary absorbed doses inside a physical anthropomorphic phantom. A general good agreement was found between calculations and measurements, thus our model was considered as validated. The University of Florida hybrid voxelized phantoms of different ages were introduced into the MCNPX validated model, and secondary neutron doses were calculated to many of these phantoms’ organs. The calculated doses were found to decrease as the organ’s distance to the treatment field increases and as the patient’s age increases. The secondary doses received by a one year-old patient may be two times higher than the doses received by an adult. A maximum dose of 16.5 mGy for a whole treatment delivering 54 Gy to the tumor was calculated to the salivary glands of a one year-old phantom. The calculated doses for a lateral proton beam incidence (left or right) may be, for some organs, two times higher than doses for an upper incidence (left or right) and four times higher than doses for an antero-superior incidence. Neutron equivalent doses were also calculated for some organs. The neutron weighting factors wR were found to vary between 4 and 10 and the equivalent doses for the considered organs reached at maximum 155 mSv during a whole treatment.

Afin d’optimiser la surveillance des travailleuses du nucléaire par anthroporadiamétrie, il est nécessaire de corriger les coefficients d’étalonnage obtenus à l’aide du fantôme physique masculin Livermore. Pour ce faire, des étalonnages numériques basés sur l’utilisation des calculs Monte Carlo associés à des fantômes numériques ont été utilisés. De tels étalonnages nécessitent d’une part le développement de fantômes représentatifs des tailles et des morphologies les plus communes et d’autre part des simulations Monte Carlo rapides et fiables. Une bibliothèque de fantômes thoraciques féminins a ainsi été développée en ajustant la masse des organes internes et de la poitrine suivant la taille et les recommandations de la chirurgie plastique. Par la suite, la bibliothèque a été utilisée pour étalonner le système de comptage du Secteur d’Analyses Médicales d’AREVA NC La Hague. De plus, une équation décrivant la variation de l’efficacité de comptage en fonction de l’énergie et de la morphologie a été développée. Enfin, des recommandations ont été données pour corriger les coefficients d’étalonnage du personnel féminin en fonction de la taille et de la poitrine. Enfin, pour accélérer les simulations, des méthodes de réduction de variance ainsi que des opérations de simplification de la géométrie ont été considérées.Par ailleurs, pour l’étude des cas de contamination complexes, il est proposé de remonter à la cartographie d’activité en associant aux mesures anthroporadiamétriques le calcul Monte Carlo. La méthode développée consiste à réaliser plusieurs mesures spectrométriques avec différents positionnements des détecteurs. Ensuite, il s’agit de séparer la contribution de chaque organe contaminé au comptage grâce au calcul Monte Carlo. L’ensemble des mesures réalisées au LEDI, au CIEMAT et au KIT ont démontré l’intérêt de cette méthode et l’apport des simulations Monte Carlo pour une analyse plus précise des mesures in vivo, permettant ainsi de déterminer la répartition de l’activité à la suite d’une contamination interne. / To optimize the monitoring of female workers using in vivo spectrometry measurements, it is necessary to correct the typical calibration coefficients obtained with the Livermore male physical phantom. To do so, numerical calibrations based on the use of Monte Carlo simulations combined with anthropomorphic 3D phantoms were used. Such computational calibrations require on the one hand the development of representative female phantoms of different size and morphologies and on the other hand rapid and reliable Monte Carlo calculations. A library of female torso models was hence developed by fitting the weight of internal organs and breasts according to the body height and to relevant plastic surgery recommendations. This library was next used to realize a numerical calibration of the AREVA NC La Hague in vivo counting installation. Moreover, the morphology-induced counting efficiency variations with energy were put into equation and recommendations were given to correct the typical calibration coefficients for any monitored female worker as a function of body height and breast size. Meanwhile, variance reduction techniques and geometry simplification operations were considered to accelerate simulations.Furthermore, to determine the activity mapping in the case of complex contaminations, a method that combines Monte Carlo simulations with in vivo measurements was developed. This method consists of realizing several spectrometry measurements with different detector positioning. Next, the contribution of each contaminated organ to the count is assessed from Monte Carlo calculations. The in vivo measurements realized at LEDI, CIEMAT and KIT have demonstrated the effectiveness of the method and highlighted the valuable contribution of Monte Carlo simulations for a more detailed analysis of spectrometry measurements. Thus, a more precise estimate of the activity distribution is given in the case of an internal contamination.