Brachytherapy refers to the therapeutic use of encapsulated radionuclides within or close to a tumor. Today brachytherapy is used as an alternative to surgery or beam therapy to treat different kinds of cancers such as breast, lung, prostate, ovarian and pancreatic, primary and metastatic hepatic tumors and rheumatoid arthritis. Microspheres are one therapy utilized in brachytherapy procedures. Despite the development of advanced equipment and methods, there is still a limited knowledge of radiation dose distribution when utilizing this technique. This study focuses on random packing of microspheres and seeks to determine dose distributions for specific cases. The Monte Carlo Neutral Particle code (MCNP) developed by Los Alamos National Laboratory is used to simulate beta particle transport. Pr-142 is the beta source utilized for all calculations. The cylinder radii are 0.1, 0.15 and 0.3 cm and sphere radii are 0.03, 0.05 and 0.07 cm. The results are verified by examining limiting cases: uniformly distributed source and line of microspheres. Based on the data collected, the correlations between the average dose, its related variance, and distance from the cylinder were determined. An approach for estimating the surface average dose was developed and suggestions regarding an approach to assess surface variance estimation were presented.

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 232-252). Available also in a digital version from Dissertation Abstracts.

Orientador: Diana Rodrigues de Pina / Resumo: A tomografia computadorizada (TC) é amplamente utilizada no diagnóstico e estadiamento de patologias da região de abdômen-pelve devido a sua alta sensibilidade e especificidade. A possibilidade de adquirir maior número de imagens em menor tempo e a maior disponibilidade de equipamentos levaram a um aumento significativo dos exames de TC e consequente aumento das doses efetivas globais fornecidas por esta modalidade. Desta forma, foram desenvolvidas ferramentas que buscam reduzir as doses de radiação dos exames sem perda da qualidade da imagem. Uma destas ferramentas é a modulação automática da corrente do tubo (automatic tube current modulation – ATCM), que permite a obtenção de exames que concordam com o princípio ALARA (as low as reasonably achievable). O objetivo deste estudo foi avaliar a qualidade da imagem e as doses de radiação de diferentes protocolos de TC de abdômen-pelve com a ferramenta ATCM. Foram avaliados cinco protocolos de TC de abdômen-pelve com a ferramenta ATCM em dois tomógrafos distintos, um 16-canais e um 64 canais. Foi utilizado um fantoma antropomórfico para avaliações dosimétricas e um fantoma analítico para avaliações objetivas de qualidade da imagem. Para a análise subjetiva da qualidade da imagem, foram utilizados 15 exames retrospectivos de pacientes submetidos a TC de abdômen-pelve. Estes exames foram avaliados por um radiologista com experiência na área de tomografia de abdômen. As três análises forneceram informações que possibilitaram a escol... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre

Made available in DSpace on 2014-06-12T23:16:39Z (GMT). No. of bitstreams: 2 arquivo9022_1.pdf: 976881 bytes, checksum: d07ddd983214cadabccc08612c10de82 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2003 / A avaliação da dose absorvida é essencial para a análise dos efeitos biológicos decorrentes de uma exposição à radiação ionizante. Neste contexto, a dosimetria citogenética, baseada na quantificação de micronúcleos, tem-se revelado importante como metodologia complementar à dosimetria física, principalmente em casos de avaliação retrospectiva da dose absorvida. Neste trabalho, investigou-se o uso da técnica de quantificação de micronúcleos na determinação da dose devido à exposição parcial do corpo humano. Para tanto, foram utilizadas amostras de sangue periférico de 5 pacientes portadoras de carcinoma de colo uterino, submetidas à radioterapia com raios gama de uma fonte de 60Co. Uma alíquota de sangue periférico de cada paciente foi adicionada separadamente ao meio de cultura RPMI 1640, com soro bovino fetal e fitohemaglutinina, e incubada durante 44 horas. Em seguida, adicionou-se citocalasina B à cultura para bloqueio da citocinese, retornando-a ao processo de incubação por mais 28 horas. Após esse período, as células foram analisadas no sentido de correlacionar a freqüência de micronúcleos em linfócitos binucleados com a dose absorvida durante o tratamento das pacientes. Os valores obtidos para as freqüências de micronúcleos após irradiação parcial da região pélvica com absorção de 0,08 Gy e 1,8 Gy foram respectivamente 0,0021 e 0,052. Estes valores estão em boa concordância com os previstos por pesquisas objetivando a determinação de curvas de dose versus freqüência de micronúcleos induzidos pela exposição à radiação gama, levando-se em consideração a fração do corpo irradiada. Os resultados apresentados neste trabalho evidenciam o emprego da quantificação de micronúcleos na avaliação retrospectiva da dose tanto na irradiação total quanto parcial do corpo humano

>Magister Scientiae - MSc / When used at the recommended and approved therapeutic dose, paracetamol is effective. Paracetamol is available in various forms and easily accessible from general dealers and pharmacies. The liquid form is the preferred form given with a device to children. Paracetamol is effective within a defined therapeutic range; however, are prescribers and caregivers using paracetamol as authorised by regulators? A qualitative review of product specific labelling and the department of health recommendations was conducted and evaluated by means of arithmetic means differences to the regulator requirements. Surveys of healthcare professionals and caregivers determined the quantity administered and to establish if a device was used. The dosing information from product specific labelling, the department of health and the regulator source were reviewed for recommended dose, frequency of administration, maximum daily dose and recommendations for overdose treatment. There are similarities and differences with the null hypothesis being proven. Product labelling and department of health recommendations do not conform to the regulator accepted therapeutic dose. There was no unambiguous legislative medicine guideline on the age of a child with children between six and twelve being underdosed with liquid paracetamol in terms of volume and strength.

This thesis describes the design, operation, and performance of an automatic system which can be used to plot isodose curves such as are used in radiation therapy. The system consists of an apparatus to move an ionization chamber by remote control along rectangular axes so that the position of curves of equal per cent dose relative to any chosen reference point in the field are found and recorded automatically. The apparatus consists of a commerical servo system which operates from the output of an accurate dose comparator to control motion of the ionization chamber along one axis so that it hunts to locate the set per cent dose in the field to be plotted. A second manually-controlled drive system is used to provide a scan motion of the ionization chamber along the second axis. The drive systems are linked by two pairs of synchros to a plotting pen which records the path of the probe. The system is capable of producing an adequate set of isodose curves for a field in two hours or less with an accuracy of better than one-half per cent of the maximum dose in the field. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Avant d'approvisionner des lots de composants pour la fabrication de systèmes orbitaux, les grandes agences du spatial (CNES, ESA, NASA, JAXA…) ainsi que les industriels du spatial (EADS, Thales,…) doivent s'assurer de la fiabilité des lots proposés par les fabricants de circuits intégrés. Dans le but d'assurer la fiabilité des composants, des tests sont réalisés suivant des recommandations afin de sélectionner et trier les composants suivant leur tenue à différents modes de défaillance. Parmi tous ces tests, certains sont typiques des applications spatiales : les tests de tenue à la dose. Cette spécificité des tests de tenue à la dose de composants destinés à des applications spatiales est due au fait que l'environnement spatial est un environnement radiatif qui provoque une ionisation dans les matériaux constituant le satellite. Suite à cette ionisation des charges sont créées dans la matière et induisent des modifications au sein des matériaux qui composent les circuits intégrés, ce qui peut provoquer des dérives de leurs caractéristiques électriques. Ces dérives des paramètres électriques en environnement spatial peuvent être perçues comme un vieillissement accéléré des composants électroniques, et des tests sont donc dédiés à prédire et s'assurer du bon fonctionnement des composants même après ce vieillissement accéléré provoqué par la dose. Dans ce travail de thèse nous nous intéressons à l'applicabilité d'une technique de test accéléré des composants bipolaires développée à l'UM2: 'La technique des Débits Commutés'. Une étude de l'effet de la polarisation pendant irradiation a été mené au cours de ce travail de thèse, afin d'appréhender l'impact de la polarisation des composants bipolaires sur les estimations obtenues de façon accélérée grâce à cette technique. / Before supplying lots of components for the manufacture of orbital systems, large space agencies (CNES, ESA, NASA, JAXA ...) and the Industrial Space (EADS, Thales, ...) should ensure the reliability lots offered by manufacturers of integrated circuits. In order to ensure reliability of components, tests are performed following recommendations to select and sort the components according to their resistance to different failure modes. Of all these tests, some are typical for space applications: tests held in the dose. The specificity of the tests held at the dose of components for space applications due to the fact that the environment is a space radiation environment which causes ionization in the materials of the satellite. Following this ionization charges are created in the material and induce changes in the materials that comprise integrated circuits, which can cause drift of their electrical characteristics. These abuses of the electrical parameters in a space environment can be viewed as accelerated aging of electronic components, and tests are dedicated to predict and verify the correct operation of the components even after the accelerated aging caused by dose. In this thesis we investigate the applicability of a technique for accelerated testing of components developed in bipolar UM2: 'The technique of Switched Flows'. A study of the effect of the polarization during irradiation was conducted during this thesis, to understand the impact of the polarization of the bipolar components on the estimates obtained in an accelerated manner using this technique.

In 2007, it was estimated that approximately 20% of the United States population spoke more than one language (Grosjean, 2012). As this statistic continues to rise, it is imperative that speech-language pathologists (SLP) are prepared to serve a linguistically inclusive caseload. Dynamic assessment (DA) allows clinicians to assess bilingual children while avoiding sources of bias that are often associated with norm-referenced testing. Utilizing DA to evaluate the multifaceted skills associated with narrative language can provide clinician’s clinical direction for intervention planning (Douglas, Chanthongthip, Ukrainetz, Spencer, and Steeve, 2017). DA is often structured as a pretest-teach-posttest model, which provides insight on current learning ability rather than current skillset. Dose refers to both the measured quantity of a therapeutic agent to be taken at one time and the specification of on-going exposure to an again (i.e., daily, weekly, monthly, etc) (Justice, 2018). In reference to speech-language pathology, dose often refers to the duration of intervention sessions over a given period. However, researchers are beginning to conceptualize dose as the engagement in therapeutic events rather than the duration of time spent in a session (Williams, 2012). In such cases, dose is represented as something the child does (e.g., produces a target phoneme) and as something the clinician does (e.g., providing exposure to a target phoneme) (Hassink & Leonard, 2010). While research on dose continues to develop, there is little research on implications of dose in bilingual populations. Due to the current COVID-19 global pandemic, many SLPs have transitioned their practice to alternative methods of delivery. The current study aims to examine the impact and opinions of practicing SLPs on dose, narrative intervention, and dynamic assessment of bilingual populations. The study surveyed licensed SLPs to obtain information on the current practices and definitions of dose, DA, and subsequent language interventions to bilingual populations.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-04-08T12:56:51Z No. of bitstreams: 0 / Made available in DSpace on 2016-04-08T12:56:51Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP