Orientador: Fernando Cendes / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-28T02:24:31Z (GMT). No. of bitstreams: 1 Altemani_JoaoMauricioCarrasco_D.pdf: 1901312 bytes, checksum: bcace160b968ce113f8f422a3db9339b (MD5) Previous issue date: 2015 / Resumo: Esse trabalho foi realizado para avaliar as doses de radiação absorvidas em exames de tomografia computadorizada em um hospital geral que atende uma grande população no Brasil. O FDA (Food and Drug Administration) considera que exames de CT com a absorção de uma dose efetiva de 10 mSv podem ser associados com um aumento na probabilidade de desenvolver um câncer fatal na proporção de 1/2000. Foram revisados 1352 relatórios de exames de tomografia computadorizada, provenientes de dois aparelhos, um com 16 e outro com 64 detectores. No aparelho de 16 detectores doses absorvidas ? 10 mSv foram observadas em 182 casos de um total de 326 pacientes (56%), enquanto no aparelho de 64 detectores essas doses foram observadas em 517 casos de um total de 996 pacientes (52%). Doses absorvidas > 100 mSv foram observadas em 16% de todos pacientes. Em ambos aparelhos , exames de abdome e de tórax + abdome apresentaram doses significantemente maiores que nos exames de pescoço, cabeça e tórax. Exames de abdome e tórax + abdome realizados com espessura de 1,25 mm no tomógrafo de 16 detectores e com 1,0 mm no aparelho de 64 detectores mostraram uma significante redução da dose absorvida em comparação com os mesmos tipos de exame realizados com espessura de 0,5 mm no aparelho de 64 detectores. Os exames de tórax realizados com espessura de 1,25 mm no tomógrafo de 16 detectores também mostraram uma significante diminuição da dose absorvida em comparação ao mesmo tipo de exame realizado no aparelho de 64 detectores com cortes de 0,5 mm. O aumento da espessura dos cortes tomográficos não causou uma significativa alteração na qualidade das imagens. Em conclusão, exames de tomografia computadorizada são frequentemente associados com altas doses de radiação absorvida indicando que os protocolos de exames devem ser reavaliados. Para exames de tomografia de abdome e de tórax + abdome , o aumento da espessura dos cortes pode proteger os pacientes de altas doses de radiação desnecessárias / Abstract: This study was conducted to evaluate the absorbed radiation doses in CT examinations in a general hospital that serves a large population in Brazil. The Food and Drug Administration (FDA) considers that CT examination with an effective dose of 10 mSv may be associated with an increase in the possibility of fatal cancer of around 1/2000. CT examinations of 1352 patients performed in two types of CT equipment (with 16 and 64 detectors) were reviewed. In the 16 detector CT scanner, an absorbed dose ?10 mSv was detected in 182 out of 326 patients (56%) whereas in the 64 detector CT scanner, in 517 out of 996 (52%). Absorbed dose > 100 mSv was seen in 16% of all patients. In both CT scanners, examinations of abdomen and thorax+ abdomen presented an absorbed dose significantly higher than neck, head and thorax. Examinations of abdomen and thorax+ abdomen performed with slices of 1,25 mm in the 16 detector CT scanner and with 1,0 mm in the 64 detector CT scanner showed a significant reduction of the absorbed dose in comparison to the same type of examination with slices of 0.5 mm in the 64 detector CT scanner. The examinations of thorax performed with slices of 1,25 mm in the 16 detector scanner also showed a significant reduction of the absorbed dose in comparison to the examinations performed with slices of 0,5 mm in the 64 detectors scanner. The increase of the slice thickness did not lead to noticeable alteration of the image quality. In conclusion, CT examinations were often associated with high doses of absorbed radiation indicating that the protocols of the examinations should be reevaluated. For CT examinations of abdomen and thorax+abdomen, the increase of the slice thickness can protect patients from unnecessarily high doses of radiation / Doutorado / Fisiopatologia Médica / Doutor em Ciências

This diploma thesis deals with creating of finite element model for the analysis of acustic waves radiation through human vocal tract and through the head surrounding space. The thesis contains a short overview of the anatomy of relevant parts and a short overview of formerly published models relevant to the topic. Then the process of creating the 3D model of human head, including the vocal tract, based on CT scans, and the mesh itself follows. This is succeeded by the computational solution taking in the acount the acoustic absorption of the vocal tract walls and radiation into the open space. The results gained are compared to relevant literature on this topic. The changes in frequency spectra in specific nodes of the mesh are reviewed and compared to relevant literature on the topic. The results could be used as basis of eventual frequention corrections of microphones used for voice diagnosis or registration in general, eg of speach or singing.