Considerações Sobre a Terapia de Captura de Nêutrons pelo Boro

Este artigo descreve a técnica de radioterapia chamada “Boron Neutron Capture Therapy” (BNCT), isto é, Terapia de Captura de Nêutrons por Boro. Serão abordados conceitos básicos em BNCT, em particular como esta técnica tem sido usada na tentativa de combater glioblastoma multiforme. Uma breve revisão histórica dos estudos clínicos feitos nas décadas de 50 e 60 será apresentada, incluindo resultados recentes do Laboratório Nacional de Brookhaven - BNL e do Instituto Tecnológico de Massachusetts - MIT. A experiência japonesa na área será comentada. Atualmente, novas ensaios clínicos no MIT e BNL foram iniciados, tentando obter a cura para o glioblastoma multiforme e melanoma intracranial periférico. Dados radiobiológicos e protocolos clínicos usados na Fase I do MIT serão apresentados. Considerações de como BNCT poderá ser aplicado no Brasil serão traçadas. O artigo aponta para a possibilidade de utilização da braquiterapia via Cf-252 acoplada à técnica de terapia de captura de nêutrons – NCT como uma alternativa simples e barata de implementação de BNCT no país

Information Theory for Arm Visuo-Motor Coordination

166 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1993.The present work addresses the information processing of visuo-motor coordination. The aim of this research is to develop an adaptive model for coordinating mechanical action of an arm according to visual information. As a result, a large neural map has been generated which has been used to guide a pneumatically driven robot arm through a vision system consisting of image boards and two stereo cameras. This engineering approach has been employed to test the algorithm which might share close features with the way that biological beings solve the same sensory-motor task.Basically, arm postures are represented through their projections onto a set of image planes. Based on the link orientations and lengths as visual primitives extracted from these images, a topological state-space is characterized. Arm kinematics is defined as transformations of topological hypersurfaces, the intersections of which represent all possible postures which any redundant arm possesses in reaching an arbitrary target position. The self-organizing feature map has learned how the topological hypersurfaces transform in the state-space during arbitrary movements of the arm. The analyses of these transformations helped in idealizing a connectionistic model for kinematics.A model for the collision-free motion of a redundant arm manipulator moving in a workspace with obstacles is presented. A mapping of the arm surface onto a set of lattices, in which visual, motor information, and surface location are encoded, is adaptively developed through a learning procedure fed by trial movements. The map, which carries topographical features of the arm surface, is then used to guide the arm avoiding collisions with obstacles in unpredictable positions.The main achievements of this research are the topographical neural model for obstacle-avoidance and the connectionist model for kinematics for redundant arms. Both models have been developed based on the analyses of a dynamic geometry, induced by the arm movements, embedded in a denoted visuo-motor space. The topographical neural model presents similar features with the motor cortex which might provide some insight for understanding biological visuo-motor control.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Gd-GLU toward NMR imaging: synthesis, characterization and breast cell uptake assay

Breast cancer cell uptake of Gd-metal is investigated based on the formation of coordinate compounds of gadolinium and glucose (Glu) molecules in solution. The hypothesis is that glucose helps Gdinternalization by complex formations constituted of Gd3+ coordinate to m-glucose molecules, whose valence was complemented by Cl- anions. Such a proposal is an insight toward a metabolic-dependent contrast-agent for cancer and inflammation in magnetic resonance image. A solution was prepared based on anhydrous d-glucose and gadolinium chloride (Gd-Glu). Uptake assays for MDA-MB-231(c231) cells were elaborated collecting incubated c231-cells with Gd-Glu and measuring metal-uptake and their concentrations by Nuclear Activation Analysis (NAA). The ionic solution was studied using Direct-Infusion Electrospray Ionization Mass-Spectrometry (ESI-MS) to identify Gd-Glu interactions. Means and standard deviations of Gd-masses were 13.3±0.8 and 12.5±0.7μg, at 361.5 μg of Gd in 3mL Gd-Glu/PBS solution, in times of 30-50 min, equivalent to the concentrations of 13404±2104 and 11347±2742 μg.g-1 in dried cells. Such values were statistically higher than the control with metal presence. ESI-MS demonstrated the m/z-signals at 516, 552, 696, 923, attributed to positively loaded-species containing Glu, Gd+3 and Cl- . In conclusion, Gd-internalization was increased in aqueous solution due to the gadolinium-glucose coordination. Such findings drive the research to MRI with Gd-Glu complexes

Evaluation of hela cell lineage response to β radiation from Holmium-166 embedded in ceramic seeds

This work studied the effects of β radiation of Ho-166 embedded in ceramic seeds on HeLa cells. Methodology consisted in the production of ceramic seeds with holmium-165 by sol-gel route. Chemical and physical characterizations of the seeds were performed. Subsequently, nuclear characterization was performed by gamma spectrometry. Experimental and theoretical activities were defined and initial dose rate were evaluated by MIRD (Medical Internal Radiation Dose Committee) methodology. The seeds were placed in confluent culture flasks and remained for six radionuclide half-lives. Biological results were represented by a clean 6 mm diameter area around the seed where the tumour cells were killed. The initial dose rate was 15.5 Gy. h-1. The maximum absorbed dose was 591.3 Gy. The features of the Ho-166 seeds suggested that such ceramic seeds were suitable for high dose rate brachytherapy

The surgical viability and radiological monitoring of brain implants of bioactive micro-seeds in an animal model

The interstitial implant is a therapeutic modality in brachytherapy of the head and neck. Presently, the seeds implanted in tumors in the central nervous system are metallic I-125. After the full emission of the radionuclide, the seed remains inert in the implanted area. Bioactive ceramic seeds have been prepared for this research group incorporating Sm-152 to be active in Sm-153. The main goal of the present study is the development of a the surgical technique for implanting the biodegradable radioactive micro-seeds in the brains of rabbits, as well as the observation of the clinical reactions of the animal after implantation of two sets of three seeds. The surgical procedure consisted of performing two separate perforations 10 mm from each other in the skull, permitting the implantation of two groups of three seeds, totaling six seeds. The results of the pilot study showed the effectiveness of the surgical procedure and of the biocompatibility of the seeds and the lack of presence of adverse reactions, functional sequels, or inflammation in a follow up 50 days post-surgery. Such seeds of reduced volume, 0.2 x 1.6 mm, could be monitored by computerized tomography 30 days after implanting

Sistema computacional para dosimetria de nêutrons e fótons baseado em métodos estocásticos aplicado a radioterapia e radiologia

OBJETIVO: Este artigo mostra um procedimento de conversão de imagens de tomografia computadorizada ou de ressonância magnética em modelo de voxels tridimensional para fim de dosimetria. Este modelo é uma representação personalizada do paciente que pode ser usado na simulação, via código MCNP (Monte Carlo N-Particle), de transporte de partículas nucleares, reproduzindo o processo estocástico de interação de partículas nucleares com os tecidos humanos. MATERIAIS E MÉTODOS: O sistema computacional desenvolvido, denominado SISCODES, é uma ferramenta para planejamento computacional tridimensional de tratamentos radioterápicos ou procedimentos radiológicos. Partindo de imagens tomográficas do paciente, o plano de tratamento é modelado e simulado. São então mostradas as doses absorvidas, por meio de curvas de isodoses superpostas ao modelo. O SISCODES acopla o modelo tridimensional ao código MCNP5, que simula o protocolo de exposição à radiação ionizante. RESULTADOS: O SISCODES vem sendo utilizado no grupo de pesquisa NRI/CNPq na criação de modelos de voxels antropomórficos e antropométricos que são acoplados ao código MCNP para modelar braquiterapias e teleterapias aplicadas a tumores em pulmões, pelve, coluna, cabeça, pescoço, e outros. Os módulos atualmente desenvolvidos no SISCODES são apresentados junto com casos exemplos de planejamento radioterápico. CONCLUSÃO: O SISCODES provê de maneira rápida a criação de modelos de voxels personalizados de qualquer paciente que podem ser usados em simulações por códigos estocásticos tipo MCNP. A combinação da simulação via MCNP com um modelo personalizado do paciente traz grandes melhorias na dosimetria de tratamentos radioterápicos