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Doctoral Thesis
DOI
10.11606/T.59.2012.tde-22072013-144625
Document
Author
Full name
Marcelo Antoniassi
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Ribeirão Preto, 2012
Supervisor
Committee
Poletti, Martin Eduardo (President)
Appoloni, Carlos Roberto
Borges, José Carlos
Costa, Alessandro Martins da
Costa, Paulo Roberto
Title in Portuguese
O espalhamento Compton de raios X no diagnóstico de neoplasias mamárias
Keywords in Portuguese
Câncer de mama
Espalhamento Compton
Radiologia
Abstract in Portuguese
Neste trabalho foram realizadas medidas de espalhamento elástico e inelástico em tecidos mamários normais e neoplásicos (benignos e malignos) usando uma energia de 17,44 keV (radiação K? ¬- Mo) e um ângulo de espalhamento de 90º (x = 0,99Å-1) com o objetivo de determinar as densidades eletrônicas (?e), número atômico efetivo (Zef) e largura a meia altura (LMA) do pico de espalhamento inelástico destes tecidos. Também foram estudadas por meio de simulações computacionais imagens obtidas por técnica de tomografia de espalhamento Compton. As metodologias experimentais foram verificadas através da análise de materiais de referência. Os valores de densidades eletrônicas e números atômicos efetivos obtidos foram comparados com dados experimentais e teóricos previamente publicados, mostrando uma boa concordância com estes (diferenças menores que 5%). Os valores de LMA obtidos indicam a possibilidade de uso deste parâmetro para obter informação sobre composição dos tecidos e se mostraram correlacionados com os valores de Zef. Os resultados também mostram que existem diferenças de ?e, Zef e LMA entre os grupos de tecidos, as quais estão associadas à composição e à histologia dos tecidos investigados. Por fim, os resultados do estudo técnica de imagem por espalhamento Compton permitiu avaliar a influência de diferentes fatores relacionados ao feixe de radiação, à geometria e à amostra, que determinam a qualidade das imagens obtidas.
Title in English
The Compton scattering of X-rays in the diagnosis of breast neoplasia
Keywords in English
Breast cancer
Compton scattering
Radiology
Abstract in English
In this work we have been measured elastic and inelastic scattering from normal and neoplastic (benign and malignant) breast tissues using a photon energy of 17.44 keV (K? radiation ¬- Mo) and a scattering angle of 90º in order to determine the electron densities (?e), effective atomic number (Zef) and full width at half maximum (FWHM) of inelastic peak of these tissues. Compton scattering imaging techniques was also studied using computational simulation. The experimental methods were checked by analyzing of standard reference materials. The values of electron densities and effective atomic numbers obtained were compared with theoretical and experimental data previously published, showing good agreement between them (differences smaller than 5%). The values of FWHM indicate the possibility of using the FWHM for obtain information about the composition of tissues showing correlation with the values of Zef. The results also show that there are differences of ?e, Zef and FWHM between groups of tissues which are associated with the composition and histology of the investigated tissues. Finally, the results of the study of the Compton scattering imaging technique allowed assessing the influence of various factors, related to the radiation beam, geometry sample, which determine the image quality.
 
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Publishing Date
2013-08-01
 
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