Diagnostic ultrasound has become invaluable to healthcare professions for the purpose of imaging soft tissue without the risk of exposure to damaging, ionizing radiation. However, the majority of commercially available transducers have rigid, fixed interfaces that cannot conform to the surface of the human body. Such limitations both introduce a potential air gap (requiring the application of ultrasound gel) and make long-term monitoring impractical. In this work, I propose a novel flexible 2D ultrasound phased array with adaptive phasing that is capable of compensating for the radius of curvature. I describe the phasing algorithm and illustrate the detrimental effect of a lack of phase correction through simulation. I conduct phase detection by using time of arrival (TOA) without additional external hardware. In addition to simulations, I provide details of the fabrication process of a flexible 16 by 16 element array. The manufactured array, with an operating frequency of 1.4MHz and bandwidth of 41.3%, was capable of generating pressures up to 600 kPa. Finally, I conduct an in-vivo human study to demonstrate the functionality of the array on a human humerus. Although visible without phase correction, the location of the bone can easily be tracked in real-time after applying the correction algorithm.

With over half a century of medical ultrasound support, proven efficacy, and increased popularity, why is it that over half our planet’s population does not have access to ultrasound imaging? In 2015 when I joined the doctoral program, I embarked to not only understand this problem but to provide a solution. This document will walk you through this journey, detailing the challenge of creating my very own ultrasound system with the purpose of it being highly accessible to people who need it the most. I had the vision to take this further; not only did I aim to create an open-source portable ultrasound- I also wanted to see this in the hands of users. This dissertation will show you how collaboration between students of varying disciplines can help propel research to the point of product development. A full ultrasound system including both hardware and software has been developed and tested using commercial ultrasound phantoms. This document will present progress chronologically, starting with the first attempts at using audible piezoelectric buzzers to generate a signal, where the first proof of concept is met. In this dissertation, you will follow the continuous development of a 1) ultrasound analog circuit, 2) mechanical transducer probe, 3) analog signal acquisition system, and 4) imaging software coupled with the user interface. The open-source portable ultrasound research has been successful in providing both hardware and software solutions, combined as a single package in an end-to-end integrated system. This has never been done before. During a time when “data is gold”, this project has also created an open platform where users can collect and share data, enabling collaborations and propulsion of open-access medical screening technologies. This research has developed the lowest-cost 3D scanning ultrasound transducer that we know of at this time. This is inherently novel and transcendental.

Thesis (MBA)--Stellenbosch University, 2014. / There is a growing trend towards the use of point of care testing in resource poor settings, in particular in the diagnosis and treatment of infectious diseases such as Human Immunodeficiency Virus (HIV), Tuberculosis (TB) and Malaria. The Alere PIMA CD4 counter is widely used as a point of care device in the staging and management of HIV. While the instrument has been extensively validated and shown to be comparable to central laboratory testing, little is known about the error rates of these devices, as well as the factors that contribute to error rates. This research was a retrospective analysis of error rates from 61 PIMA point of care devices deployed in nine African countries belonging to Medisciens Sans Frontiers. The data was collected between January 2011 and June 2013. The objectives of the study were to determine the overall error rate and, where possible, determine the root cause. Thereafter the study aimed to determine the variables that contribute to the root causes and make recommendations to reduce the error rate. The overall error was determined to be 13.2 percent. The errors were further divided into four root causes and error rates assigned to each root cause based on the error codes generated by the instrument. These error rates were found to be operator error (48.4%), instrument error (2.0%), reagent/cartridge error (1%) and sample error (4.3%). It was found that a high percentage of the errors were ambiguous (44.3%), meaning that they had more than one possible root cause. A systems-based knowledge management approach was used to create a qualitative politicised influence diagram, which described the variables that affect each of the root causes. The influence diagram was subjected to loop analysis where individual loops were described in terms of the knowledge type (tacit or explicit), the knowing type (know-how, know-who, know-what and know-why), and the actors involved with each variable. Where possible, the variable was described as contributing to pre-analytical, analytical or post-analytical error. Recommendations to reduce the error rates for each of the variables were then made based on the findings.

Combined atomic force microscopy-scanning electrochemical microscopy (AFM-SECM) is capable of providing simultaneous topographical and electrochemical imaging at sample surfaces. Integration of amperometric biosensors at tip-integrated electrodes recessed from the apex of the AFM tip further enhances the versatility of such bifunctional probes. Of particular interest to this work was the detection of adenosine triphosphate (ATP) at a cellular level, since ATP is involved in many biologically relevant processes. There are challenges concerning the integration of biosensors into bifunctional AFM-SECM probes. This thesis focuses on addressing and advancing several of these limitations. Thin insulation layers are important for AFM-SECM based applications to enhance AFM and SECM performance. Plasma-polymerized fluorocarbon membranes are introduced as novel thin film insulation materials for AFM-SECM probes. Insulation layers with a thickness of < 300 nm were found to exhibit excellent insulating properties and satisfying temporal stability for successful application in AFM-SECM experiments. Furthermore new approaches for increasing the electrode area in conventionally focused ion beam (FIB) fabricated AFM-SECM probes were implemented, since enhancement of the current response in conjunction with biosensing experiments is required. Ion beam induced deposition (IBID) was used to generate platinum carbon (PtC) deposits at AFM-SECM probes, thereby successfully increasing the tip-integrated electrode area. PtC composites were thoroughly characterized in terms of their physical and electrochemical properties. Since a high carbon fraction in the PtC composite was inhibiting the charge transfer kinetics at the electrode surface for certain analytes, several pre-treatment strategies were investigated including annealing, UV/ozone treatment, and FIB milling. FIB milling proved to be the most promising procedure improving charge transfer properties at the electrode along with fabrication compatibility at AFM-SECM probes. The last part of this thesis aimed at providing fundamental studies on AFM-SECM application at live epithelial cell monolayers. AFM was used in different imaging modes to characterize the topography of epithelial cells. ATP detection at epithelial cells was achieved with amperometric biosensors combined with non-invasive SECM. Biosensors were further miniaturized at batch-fabricated AFM-SECM probes enabling laterally-resolved detection of ATP at epithelial cells. Additionally, PtC composite materials were evaluated for applicability as transducer platforms for enzymatic biosensors.

Introdução: Os avanços tecnológicos no desenvolvimento de medidas preventivas são indispensáveis no processo de manutenção da qualidade de vida dos seres humanos. O incremento de novos métodos avaliativos para estruturas complexas como a coluna vertebral e, mais especificamente a coluna lombossacral, é demanda constante no âmbito de pesquisa científica. Objetivo: Investigar a correlação e a concordância entre diferentes métodos radiográficos de avaliação da concavidade lombossacral e desenvolver um protocolo de avaliação dessa curvatura por meio de fotogrametria. Metodologia: A seleção da amostra ocorreu no município de Curitiba-PR, totalizando 58 indivíduos de ambos os sexos, com idades entre 18 e 28 anos. Nos procedimentos de tratamento de imagem e dos critérios de inclusão foram detectadas seis perdas técnicas, reduzindo a amostra para 52 indivíduos. Para o desenvolvimento da nova técnica utilizou-se: uma câmera fotográfica digital Samsung® de 14,2 Mega Pixels, um tripé da marca Midas® e marcadores adesivos circulares da marca Pimaco®. Os procedimentos relacionados às coletas da imagem radiográficas foram realizados em um centro diagnóstico por imagem. Os ângulos da concavidade lombossacral foram avaliados por sete técnicas diferentes (Centroide, Cobb1L1-S1, Cobb2L1-L5, Cobb3L2-S1, Cobb4T12-S1, Tangente Posterior e Trall) e ainda, por duas novas técnicas com imagens fotográficas (Cobb Foto e Trall Foto). Resultados: Durante a elaboração da nova técnica, detectou-se a necessidade do desenvolvimento de um marcador metálico proeminente, para ser observado nas fotografias e radiografias em vistas laterais. Apesar dos baixos valores de concordância entre os métodos radiográficos, foram constatados altos coeficientes de correlação entre algumas técnicas: Cobb4 T12i-S1s e Cobb1 L1s-S1s (0,893), Cobb4 T12i-S1s e Cobb2 L1s-L5i (0,820), Cobb3 L2s-S1s e Cobb1 L1s-S1s (0,810). As técnicas fotogramétricas para a análise da coluna lombossacral apresentaram correlações moderadas e fracas quando comparados aos testes radiográficos. As medidas de Trall Foto em relação às medidas de Cobb L1s-S1s e Cobb3 L2s-S1s apresentaram valores de r= 0,40 e 0,45, respectivamente. Adicionalmente, promoveu-se uma classificação categórica dos valores angulares obtidos através de cada método, tanto aqueles que são validados na radiologia, quanto àqueles desenvolvidos por fotogrametria. Com nos resultados obtidos, optou-se pela análise de uma nova variável, o ponto de inflexão entre a cifose torácica e a lordose lombar. Este ponto de inflexão apresentou maior incidência na região entre a décima segunda vértebra torácica e a primeira lombar (63,5%). Conclusão: Pode-se concluir que a diversidade de referências anatômicas utilizadas nas técnicas estudadas deve ser considerada no momento da escolha daquela a ser aplicada, em diferentes pacientes, dependendo do posicionamento referente ao ponto de inflexão toracolombar, pois o conhecimento de sua localização permite a escolha da técnica a ser empregada com mais exatidão. As técnicas de avaliação desenvolvidas a partir da fotogrametria (Cobb Foto e Tall Foto) não apresentaram valores estatísticos suficientemente compatíveis para a substituição do método radiográfico. / Introduction: Technological advances in the development of preventive measures are indispensable in the process of maintaining the quality of life of human beings. The rise of new methods of assessment of complex structures such as the spine, and more specifically the lumbosacral spine is in constant demand for scientific research. Objective: To investigate the correlation and agreement between different radiographic methods for evaluation of lumbosacral concavity and develop a protocol for assessment of curvature through Photogrammetry. Methodology: The sample selection was in Curitiba-PR, totaling 58 individuals of both sexes, aged between 18 and 28 years. In image processing procedures and criteria for inclusion were detected six technical losses, reducing the sample to 52 individuals. For the development of the new technique was used: a digital camera Samsung ® 14.2 Mega Pixels, a tripod Midas ® and markers adhesives of brand Pimaco®. During construction of the new technique, we detected the need to develop metallic marker of prominence to be seen in the photographs and radiographs in lateral views. The procedures related to collect radiographic image were carried out in partnership with a diagnostic imaging center of a hospital in the capital of Curitiba. The angles of the concavity lumbosacral were evaluated seven different techniques (Centroid, Cobb1L1-S1, Cobb2L1-L5, Cobb3L2-S1, Cobb4T12-S1, Posterior tangent and Trall) and also by two new techniques with photograph (Cobb Photo e Trall Photo). Results: Despite the low values of correlation between radiographic methods, high correlation coefficients were found between some techniques: Cobb4 T12i-S1s e Cobb1 L1s-S1s (0,893), Cobb4 T12i-S1s e Cobb2 L1s-L5i (0,820), Cobb3 L2s-S1s e Cobb1 L1s-S1s (0,810). The techniques the photogrammetric analysis of the lumbosacral spine demonstrated correlation moderate to weak when compared to radiographic tests. The Measures of Trall Photo in 0, 45, respectively. Additionally, we promoted a categorical classification of angle values obtained by each method, both those validated in radiograph, and developed by photogrammetry. With these results, we opted for the analysis of a new variable, the tipping point between the thoracic kyphosis and lumbar lordosis. This inflection point presented higher incidence in the region between the twelfth thoracic vertebra and the L1 (63,5%). Conclusion: It was concluded that the diversity of anatomical references used in the studied techniques should be considered when choosing to appli in different patients, depending on the position assigned to the inflection point thoracolumbar, because knowledge of its location allows choice of technique to be used more accurately. Assessment techniques developed from photogrammetry (Cobb Photo e Tall Photo) showed no statistical values sufficiently compatible to replace the radiographic method.

Introdução: Os avanços tecnológicos no desenvolvimento de medidas preventivas são indispensáveis no processo de manutenção da qualidade de vida dos seres humanos. O incremento de novos métodos avaliativos para estruturas complexas como a coluna vertebral e, mais especificamente a coluna lombossacral, é demanda constante no âmbito de pesquisa científica. Objetivo: Investigar a correlação e a concordância entre diferentes métodos radiográficos de avaliação da concavidade lombossacral e desenvolver um protocolo de avaliação dessa curvatura por meio de fotogrametria. Metodologia: A seleção da amostra ocorreu no município de Curitiba-PR, totalizando 58 indivíduos de ambos os sexos, com idades entre 18 e 28 anos. Nos procedimentos de tratamento de imagem e dos critérios de inclusão foram detectadas seis perdas técnicas, reduzindo a amostra para 52 indivíduos. Para o desenvolvimento da nova técnica utilizou-se: uma câmera fotográfica digital Samsung® de 14,2 Mega Pixels, um tripé da marca Midas® e marcadores adesivos circulares da marca Pimaco®. Os procedimentos relacionados às coletas da imagem radiográficas foram realizados em um centro diagnóstico por imagem. Os ângulos da concavidade lombossacral foram avaliados por sete técnicas diferentes (Centroide, Cobb1L1-S1, Cobb2L1-L5, Cobb3L2-S1, Cobb4T12-S1, Tangente Posterior e Trall) e ainda, por duas novas técnicas com imagens fotográficas (Cobb Foto e Trall Foto). Resultados: Durante a elaboração da nova técnica, detectou-se a necessidade do desenvolvimento de um marcador metálico proeminente, para ser observado nas fotografias e radiografias em vistas laterais. Apesar dos baixos valores de concordância entre os métodos radiográficos, foram constatados altos coeficientes de correlação entre algumas técnicas: Cobb4 T12i-S1s e Cobb1 L1s-S1s (0,893), Cobb4 T12i-S1s e Cobb2 L1s-L5i (0,820), Cobb3 L2s-S1s e Cobb1 L1s-S1s (0,810). As técnicas fotogramétricas para a análise da coluna lombossacral apresentaram correlações moderadas e fracas quando comparados aos testes radiográficos. As medidas de Trall Foto em relação às medidas de Cobb L1s-S1s e Cobb3 L2s-S1s apresentaram valores de r= 0,40 e 0,45, respectivamente. Adicionalmente, promoveu-se uma classificação categórica dos valores angulares obtidos através de cada método, tanto aqueles que são validados na radiologia, quanto àqueles desenvolvidos por fotogrametria. Com nos resultados obtidos, optou-se pela análise de uma nova variável, o ponto de inflexão entre a cifose torácica e a lordose lombar. Este ponto de inflexão apresentou maior incidência na região entre a décima segunda vértebra torácica e a primeira lombar (63,5%). Conclusão: Pode-se concluir que a diversidade de referências anatômicas utilizadas nas técnicas estudadas deve ser considerada no momento da escolha daquela a ser aplicada, em diferentes pacientes, dependendo do posicionamento referente ao ponto de inflexão toracolombar, pois o conhecimento de sua localização permite a escolha da técnica a ser empregada com mais exatidão. As técnicas de avaliação desenvolvidas a partir da fotogrametria (Cobb Foto e Tall Foto) não apresentaram valores estatísticos suficientemente compatíveis para a substituição do método radiográfico. / Introduction: Technological advances in the development of preventive measures are indispensable in the process of maintaining the quality of life of human beings. The rise of new methods of assessment of complex structures such as the spine, and more specifically the lumbosacral spine is in constant demand for scientific research. Objective: To investigate the correlation and agreement between different radiographic methods for evaluation of lumbosacral concavity and develop a protocol for assessment of curvature through Photogrammetry. Methodology: The sample selection was in Curitiba-PR, totaling 58 individuals of both sexes, aged between 18 and 28 years. In image processing procedures and criteria for inclusion were detected six technical losses, reducing the sample to 52 individuals. For the development of the new technique was used: a digital camera Samsung ® 14.2 Mega Pixels, a tripod Midas ® and markers adhesives of brand Pimaco®. During construction of the new technique, we detected the need to develop metallic marker of prominence to be seen in the photographs and radiographs in lateral views. The procedures related to collect radiographic image were carried out in partnership with a diagnostic imaging center of a hospital in the capital of Curitiba. The angles of the concavity lumbosacral were evaluated seven different techniques (Centroid, Cobb1L1-S1, Cobb2L1-L5, Cobb3L2-S1, Cobb4T12-S1, Posterior tangent and Trall) and also by two new techniques with photograph (Cobb Photo e Trall Photo). Results: Despite the low values of correlation between radiographic methods, high correlation coefficients were found between some techniques: Cobb4 T12i-S1s e Cobb1 L1s-S1s (0,893), Cobb4 T12i-S1s e Cobb2 L1s-L5i (0,820), Cobb3 L2s-S1s e Cobb1 L1s-S1s (0,810). The techniques the photogrammetric analysis of the lumbosacral spine demonstrated correlation moderate to weak when compared to radiographic tests. The Measures of Trall Photo in 0, 45, respectively. Additionally, we promoted a categorical classification of angle values obtained by each method, both those validated in radiograph, and developed by photogrammetry. With these results, we opted for the analysis of a new variable, the tipping point between the thoracic kyphosis and lumbar lordosis. This inflection point presented higher incidence in the region between the twelfth thoracic vertebra and the L1 (63,5%). Conclusion: It was concluded that the diversity of anatomical references used in the studied techniques should be considered when choosing to appli in different patients, depending on the position assigned to the inflection point thoracolumbar, because knowledge of its location allows choice of technique to be used more accurately. Assessment techniques developed from photogrammetry (Cobb Photo e Tall Photo) showed no statistical values sufficiently compatible to replace the radiographic method.

A traqueostomia é uma via aérea artificial que pode ser plástica ou metálica. Esta, para aplicação de pressão positiva necessita de um conector adaptador. Objetivo: desenvolver um conector para acoplar a cânula metálica à válvula exalatória. Metodologia: foram desenvolvidos três modelos para a peça conectora, a partir das medidas de uma cânula metálica número 5 e de duas válvulas exalatórias. Os dois primeiros modelos foram usinados em material poliamídico, sendo o primeiro com formato de funil e angulação de 140o próximo à extremidade conectável à cânula; o segundo com formato predominantemente cônico e angulação específica de 2o. O terceiro protótipo seguiu o modelo do segundo; porém, com resina e produzido em impressora 3D. Os conectores adaptadores foram testados com duas válvulas exalatórias, confeccionadas em acrílico, e identificadas como I e II. A válvula I é um tubo com orifício exalatório e uma entrada para oxigenioterapia. A válvula II contém dois tubos encaixáveis e com fuga contínua. Os testes envolveram: análise de vazamento com gerador de pressão positiva, programado em 7,5, 13 e 20 cmH2O, durante 1-2 h, em um modelo pulmonar analógico; medidas de pressões de entrada e de saída; ensaios mecânicos destrutivos; simulação computacional de fluxo e reação à esterilização. Resultados: obteve-se uma velocidade de fluxo maior no trajeto da via aérea superior até o brônquio esquerdo e distal à via aérea. Os testes destrutivos atingiram tensões máximas de 71,43 e 75,44 MPa, respectivamente, indicando que a poliamida é mais frágil que a resina. As medidas de vazamento apresentaram menor média, 18,8 (±10,78) l/m, na combinação da peça em resina com a válvula exalatória I. Na medida das pressões de entrada e saída do gerador, o erro encontrado foi de 4,48% sobre os valores das três pressões aplicadas. Quanto à esterilização, o procedimento em óxido de etileno afetou as dimensões e funcionalidade da peça em resina, mas as peças usinadas permaneceram inalteradas. Nos procedimentos de peróxido de hidrogênio e autoclave, não houve alteração na funcionalidade da peça em resina. Conclusões: A peça usinada, esterilizada apenas com óxido de etileno, permaneceu inalterada após o procedimento. A peça prototipada, submetida ao óxido de etileno, peróxido de hidrogênio e à autoclave apresentou alteração dimensional e funcional com o óxido de etileno. Quanto ao vazamento, a melhor solução é a combinação da peça em resina com a válvula I, exigindo menos do sistema de compensação. Para resultados conclusivos, aguardam-se os ensaios in vivo. / Tracheostomy is an artificial airway which can be made by plastic or metal cannula. For applying treatment with positive pressure it needs an adapter connector. Objective: to create a connector to be attached between the metal cannula and the exhalation valve. Method: for the connector device, three models have been developed, from the dimensions of a metal cannula number 5 and two exhalation valves. The first two models were machined with polyamide material, having the first one funnel-shaped with an angle of 140° closed to the end connectable to the cannula; the second having predominantly conical shape and angular opening of 2°. The third prototype was built similarly to the second model. However, it is made by resin and produced on a 3D printer. Connectors were tested with two exhalation valves, made of acrylic and identified as I and II. Valve I is a tube with an exhalation hole and an inlet for oxygen therapy. Valve II contains two dockable continuous drain pipes. The evaluation tests involved: leakage analysis using positive pressure generator set at 7.5, 13 and 20 cmH2O for 1-2 h, in an analog lung model; input and output pressure measurements; destructive mechanical testing; computer-based flow simulation and reaction to sterilization. Results: it was obtained a higher flow velocity along the upper airway path till the left bronchus and distal to the air. Destructive testing reached maximum stresses of 71.43 and 75.44 MPa for the samples 1 and 2, respectively. Flow leaks' measurements had shown lower average for the combination of resin with exhalation valve I (18.8 (± 10.78) l/m). For the measures of input pressure and output of the generator, the error was found to be 4.48 % on the values of the three applied pressures. Regarding sterilization, the procedure with ethylene oxide has affected the dimensions and functionality of the resin-based device, but the machined prototypes remained unchanged. Concerning the hydrogen peroxide and autoclaving procedures, there was no change on the resin model ́s functionality. Conclusions: with relation to the flow leaks, the combination where occurred the least leaks was the resin based device with valve I. The machined connector, which was sterilized only with ethylene oxide, remained unchanged after the procedure. The prototype which was submitted to ethylene oxide, hydrogen peroxide and autoclave, had introduced dimensional and functional changes with the ethylene oxide. As for the flow leak, the best solution is the combination of the resin-based connector with valve I, demanding less of the compensation system. For conclusive results, in vivo essays are expected.

A Ressonância Magnética (RM) é um método de diagnóstico por imagem que apresenta vantagens em relação aos demais métodos, o que fez com que o número de equipamentos instalados nos grandes centros brasileiros aumentasse 88% nos últimos 5 anos e cerca de 508% nos últimos 15 anos, o que demonstra a importância dessa modalidade como meio de diagnóstico por imagem. Para garantir uma imagem médica com qualidade diagnóstica, é necessário que os equipamentos sejam monitorados quanto à qualidade das imagens que produzem. Por isso, com o objetivo de manter a qualidade das imagens médicas em seu mais alto nível e assegurar o bom funcionamento dos equipamentos, é que são implementados programas de Controle de Qualidade (CQ) em RM. No Brasil, há poucos trabalhos publicados discutindo os procedimentos para o CQ em RM e não existem normas nacionais para sua regulamentação. A normatização e recomendação sobre CQ em equipamentos de RM se restringe a trabalhos de organizações internacionais. Os objetos de teste comercialmente disponíveis mais conhecidos são o objeto de teste (OT) Eurospin e o American College of Radiology (ACR), sendo que diversos grupos de pesquisa internacionais têm publicado trabalhos sobre o CQ em RM com resultados promissores utilizando esses objetos. O objetivo desse trabalho é estudar a metodologia de utilização dos objetos de teste Eurospin e ACR, comparando as diferenças de execução dos testes, resultando em um material de orientação para utilização destes objetos de teste na rotina de CQ em RM. Os parâmetros de qualidade – razão sinal ruído (RSR), uniformidade, distorção geométrica, espessura de corte, posição de corte, resolução espacial de alto contraste, porcentagem do sinal fantasma e detecção de baixo contraste – foram avaliados e executados em dois equipamentos de RM de 1,5 T com os objetos de teste ACR e Eurospin. Os dois equipamentos de RM utilizados apresentaram resultados de todos os testes dentro dos critérios de aceitação. Os objetivos desse trabalho foram alcançados, visto que foi possível estudar a metodologia de utilização dos objetos de teste Eurospine ACR e comparar as formas de execução, tendo sido elaborado um protocolo operacional para realização do CQ em RM. / Magnetic resonance imaging (MRI) is a method of diagnostic imaging which has advantages over other methods, which caused the number of installed equipment in the large Brazilian centers increased 88% over the past 5 years and about 508% in the last 15 years, which shows the importance of this method as a diagnostic imaging modality. To ensure medical imaging with diagnostic quality, it is necessary that the equipment is monitored for quality of the images they produce. Therefore, in order to maintain the quality of medical images at the highest level and ensure the proper performance of equipment, are implemented Quality Control (QC) programs in MRI. In Brazil, there are few works published discussing the procedures for the QC in MRI and there are no national standards for its regulation. The standardization and recommendation on QC in MRI is restricted to the work of international organizations. The best-known commercially available test objects are the test object (TO) Eurospin and the American College of Radiology (ACR), and several international research groups have published studies on QC in MRI with promising results using these objects. The aim of this work is to study the methodology of use of the test objects Eurospin and ACR, comparing the differences in test implementation, resulting in a guidance material for use of the test objects in the QC routine in MRI. The quality parameters – signal noise ratio (SNR), uniformity, geometric distortion, slice thickness, slice position, high-contrast spatial resolution, percentage of ghost signal and low contrast detection – were evaluated and performed in two MRI equipment of 1.5 T with the test objects ACR and Eurospin. The two MRI systems showed results of all tests within the acceptance criteria. The objectives of this study were achieved, since it was possible to study the methodology of using Eurospin and ACR test objects and compare the performance, and an operational protocol guide for performing the QC in MRI was developed.

A Estimulação Elétrica Funcional (EEF), que utiliza pulsos elétricos para a reprodução de movimentos artificialmente, é uma técnica consolidada no tratamento de pacientes em reabilitação. Para tal, são usados equipamentos específicos para a geração destes sinais, chamados de eletroestimuladores. O presente trabalho descreve o desenvolvimento de um eletroestimulador portátil com oito canais independentes e síncronos entre si, permitindo a programação temporal de ativação dos seus canais, o que proporciona a reprodução de movimentos artificiais similares aos reais. O hardware do dispositivo possui dimensões reduzidas (115 mm X 162 mm X 43 mm) e gera estímulos elétricos bifásicos com amplitudes de ±100 mA. Estes pulsos possuem durações de 100 a 800 µs e freqüência de 50 a 1000 Hz. Utilizou-se uma interface em display líquido (LCD) sensível ao toque (touchscreen), para a interação do usuário com o software embarcado, que é responsável por controlar todo o sistema. Um software desktop foi criado para a geração dos programas estimulatórios, contendo também um simulador virtual que por meio de um modelo humano 3D permite ajustes no programa estimulatório antes de executá-lo em um paciente. O equipamento foi desenvolvido de forma a cumprir as normas de segurança elétrica da ABNT referentes a equipamentos eletromédicos para estimulação neuromuscular. Testes in vitro foram feitos seguindo os roteiros descritos nessas normas para garantir a conformidade de seu funcionamento e dos pulsos elétricos fornecidos pelo dispositivo. O equipamento apresentou resultados dentro dos limites de segurança, de temperaturas excessivas, de exatidão de dados de operação, de proteção contra características de saída incorreta e, contra erros humanos. Também, 10 voluntários participaram de testes in vivo com o objetivo de validação clínica do dispositivo. A validação consistiu na comparação de amplitudes de movimento obtidas pelos voluntários em reproduções de movimentos funcionais durante o uso do eletroestimulador desenvolvido e de um comercial. Com erro máximo de 3%, o eletroestimulador desenvolvido foi capaz de executar movimentos funcionais por meio de parâmetros da EEF, podendo ser útil no tratamento de reabilitação física. / The use of electrical pulses for artificial reproduction movements, or Functional Electrical Stimulation (FES), is a consolidated technique for treating patients in rehabilitation. For this use, special instruments are employed to generate the signals, known as electrostimulators. This work describes the development of a portable electrostimulator with eight independent and synchronous channels, allowing a temporal activation program of their channels and making it possible to reproduce artificial movements similar to real ones. The hardware of this device has small dimensions (115 mm X 162 mm X 43 mm) and generates biphasic electrical pulses with maximum amplitudes of ± 100 mA. The pulses have durations from 100 to 800 µs and frequency from 50 to 1000 Hz. Also, there is an interface with a touchscreen liquid crystal display (LCD) for user interaction with the embedded software, which is responsible for controlling the complete system. A desktop software was developed to generate stimulatory programs, containing a virtual simulator that, using a 3D human model, allows adjustments in the stimulatory program before running it on a patient. The instrument complies with the electrical standards of the ABNT relating to electromedical equipment for neuromuscular stimulation. In vitro tests were performed following the rules described in standards to ensure compliance of functioning, and the electrical pulses provided by the device. As a result, the device showed values within the standard limits of safety, excessive temperatures, accuracy of operating data, protection of incorrect output, and human errors. Also, ten volunteers participated of in vivo tests to validate the instrument. The in vivo tests consisted on a comparison of movement ranges obtained by the volunteers in reproduction of functional movements during the use of a commercial electrostimulator and the developed one. With a maximum error of 3%, the developed instrument was capable to perform functional movements, and thus may be useful in treatment of physical rehabilitation.

Este trabalho apresenta o desenvolvimento de um estimulador galvânico vestibular para ser usado em experimentos de imageamento por ressonância magnética funcional (fMRI). Em experiências de fMRI é necessário a produção de estímulos somatossensoriais no paciente. Os estímulos devem ser sincronizados com a sequência de pulsos da fMRI. O estimulador foi dividido em circuitos analógicos (colocados dentro da sala do magneto) e circuitos digitais (sala de comando do sistema de MRI). A comunicação entre os circuitos é feita através de fibra óptica. Experimentos de fMRI realizados com voluntários demonstraram que o estimulador proposto é capaz de manter a sincronização com sistema de fMRI e pode ser usado para localizar as áreas do cérebro que são ativados pelo sistema vestibular. / This work presents the development of a galvanic vestibular stimulator to be used in functional magnetic resonance imaging experiments (fMRI). In fMRI experiments it is required the production of somatosensory stimuli in the patient must be sincronized with the fMRI pulse sequence. The stimulator circuits were divided in analog circuits (placed within the magnet room) and digital circuits (placed in the MRI command room). The communication between the circuits is made through optical fiber. fMRI experiments performed with volunteers demonstrated that the proposed stimulator is able to keep the sincronization with the MRI system and can be used to locate the brain areas that are activated by the vestibular system.