Browsing by Author "Rodrigues, J. A."
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- Análise de imagens de cintigrafia renal com um método de elementos finitosPublication . Vieira, Lina; Rodrigues, J. A.Objetivo do estudo: Avaliar a reprodutibilidade de um método variacional, discretizado por um método de elementos finitos, na análise de imagens de cintigrafia renal. Conclusões: A metodologia apresentada permite de forma automática obter resultados idênticos aos métodos tradicionais quanto à captação relativa renal, forma e ao número de pixeis.
- Developments on finite element methods for medical image supported diagnosticsPublication . Almeida, Ana; Barbosa, J. I.; Carvalho, A.; Loja, M. A. R.; Portal, R.; Rodrigues, J. A.; Vieira, LinaVariational image-processing models offer high-quality processing capabilities for imaging. They have been widely developed and used in the last two decades, enriching the fields of mathematics as well as information science. Mathematically, several tools are needed: energy optimization, regularization, partial differential equations, level set functions, and numerical algorithms. For this work we consider a second-order variational model for solving medical image problems. The aim is to obtain as far as possible fine features of the initial image and identify medical pathologies. The approach consists of constructing a regularized functional and to locally analyse the obtained solution. Some parameters selection is performed at the discrete level in the framework of the finite element method. We present several numerical simulations to test the efficiency of the proposed approach.
- Imobilização da região da cabeça por prototipagem rápida para fins de diagnóstico e terapêuticaPublication . Craveiro, D. S.; Loja, M. A.; Vieira, Lina; Sousa, Eva; Costa, Durval C.; Parafita, Rui; Rodrigues, J. A.Objetivo do estudo: Modelar e testar, por procedimentos de prototipagem rápida, máscaras de imobilização da cabeça através da imagem médica. Conclusões: Dispositivos de imobilização construídos por prototipagem rápida têm características favoráveis para aplicação em imobilização em diagnóstico e terapia. Para dispositivos de imobilização da cabeça as diferenças encontradas na análise estática realizada foram mínimas.
- Interpretation of medical images: end of subjectivity?Publication . Almeida, Ana; Vieira, Lina; Figueiredo, Sérgio; Rodrigues, J. A.The aim of the study: To describe the importance of blood smears images, and the renal scintigraphy, in clinical diagnosis and to describe the relevant aspects that must be analyzed in such images, taking into account the reduction of the subjectivity and variability in the interpretation of the findings. Final considerations: Interpretation of either blood smears or renal scintigraphy is associated with training and expertise. These are allied to the subjectivity of the observer, is a limitation in the quality and reproducibility of the results.
- Radiotherapy-customized head immobilization masks: from modeling and analysis to 3D printingPublication . Loja, Amélia; Craveiro, D. S.; Vieira, Lina Oliveira; Sousa, Eva; Rodrigues, J. A.; Portal, R. J. F.Immobilization devices may be a valuable aid to ensure the improved effectiveness of radiotherapy treatments where constraining the movements of specific anatomical segments is crucial. This need is also present in other situations, specifically when the superposition of various medical images is required for fine identification and characterization of some pathologies. Because of their structural characteristics, existing head immobilization systems may be claustrophobic and very uncomfortable for patients, during both the modeling and usage stages. Because of this, it is important to minimize all the discomforts related to the mask to alleviate patients’ distress and to simultaneously guarantee and maximize the restraint effectiveness of the mask. In the present work, various head immobilization mask models are proposed based on geometrical information extracted from computerized tomography images and from 3D laser scanning point clouds. These models also consider the corresponding connection to a radiotherapy table, as this connection is easily altered to accommodate various manufacturers’ solutions. A set of materials used in the radiotherapy field is considered to allow the assessment of the stiffness and strength of the masks when submitted to typical loadings.
- Radiotherapy-customized head immobilization masks: from modeling and analysis to 3D printingPublication . Loja, M. A. R.; Craveiro, D. S.; Vieira, Lina; Sousa, Eva; Rodrigues, J. A.; Portal, R. J.Immobilization devices may be a valuable aid to ensure the improved effectiveness of radiotherapy treatments were constraining the movements of specific anatomical segments is crucial. This need is also present in other situations, specifically when the superposition of various medical images is required for fine identification and characterization of some pathologies. Because of their structural characteristics, existing head immobilization systems may be claustrophobic and very uncomfortable for patients, during both the modeling and usage stages. Because of this, it is important to minimize all the discomforts related to the mask to alleviate patients’ distress and to simultaneously guarantee and maximize the restraint effectiveness of the mask. In the present work, various head immobilization mask models are proposed based on geometrical information extracted from computerized tomography images and from 3D laser scanning point clouds. These models also consider the corresponding connection to a radiotherapy table, as this connection is easily altered to accommodate various manufacturers’ solutions. A set of materials used in the radiotherapy field is considered to allow the assessment of the stiffness and strength of the masks when submitted to typical loadings.