Dissertations / Theses on the topic 'Anatomical simulator'

L'usage d'humains virtuels s'est démocratisé à de nombreuses activités ces dernières années.Au-delà de la chirurgie virtuelle, les corps virtuels sont de plus en plus utilisés pour concevoir des dispositifs médicaux, des véhicules et des outils de notre quotidien plus généralement.Ils se sont avérés être également d'extraordinaires supports à l'apprentissage de l'anatomie.De récents films (Avatar, Le seigneur des anneaux, etc) ont démontré que l'anatomie et la biomécanique peuvent être utilisées pour concevoir des personnages d'une grande qualité.Cependant, reproduire le comportement des structures anatomiques demeure une tâche complexe, et de nombreuses connaissances variées sont nécéssaires à la mise en place de simulation de qualité de nos organes. Ceci fait de la modélisation pour la simulation d'humains une problématique non résolue, une tâche fastidieuse, mais également un sujet de recherche fascinant.À travers ces travaux de thèse, nous abordons cette problématique de la construction de systèmes musculo-squeletiques pour ces domaines variés : animation, biomécanique et aide à l'apprentissage.Notre objectif est de simplifier le processus entier de création en le rendant plus intuitif et plus rapide.Notre approche consiste à pallier à chacune des difficultés, à savoir : la représentation et la manipulation de connaissances anatomiques, la modélisation géométrique et la simulation efficace de systèmes musculosquelettiques grâce à trois principalescontributions introduites durant ces travaux de recherche.Notre première contribution se focalise sur la construction biomécanique d'un modèle hybride du rachis lombaire.Dans ces travaux, nous montrons que les approches hybrides combinant des systèmes de corps rigides et des modèles éléments finis permettent d'obtenir des simulations en temps intéractifs, précises, et respectant les principes de l'anatomie et de la mécanique.Notre seconde contribution s'intéresse aux problématiques liées à la complexité des connaissances anatomiques, physiologiques et fonctionnelles. En se basant sur une ontologie de l'anatomie et une ontologie inédite de la physiologie humaine, nous introduisonsun pipeline pour la construction automatique de modèles simulant les fonctions de nos organes.Celles-ci permettent d'exploiter les connaissances anatomiques complexes via des requêtes simples.Les sorties de ces requêtes sont utilisées pour créer des modèles simulables retranscrivant les aspects fonctionnels tels qu'ils ont été formalisés et décrits par les anatomistes.Enfin, notre troisième contribution : le transfert d'anatomie, permet d'adapter les modèles géométriques et mécaniques à la morphologie de patients spécifiques.Cette nouvelle méthode de recalage permet de reconstruire automatiquement l'anatomie interne d'un personnage défini par sa peau en transférant les organes d'un personnage de référence.Elle permet de pallier à la nécessité de re-construire ces géometries pour chaque nouvelle simulation, et contribue ainsi à accélérer la mise en place de simulations spécifiques à une grande variété d'individus de morphologie différente
The use of virtual humans has spread in various activities in recent years.Beyond virtual surgery, virtual bodies are increasingly used to design medical devices, vehicles, and daily life hardware more generally.They also turn out to be extraordinary supports to learn anatomy.Recent movies (Avatar, Lord of the Rings, etc) demonstrated that anatomy and biomechanics can be used to design high-quality characters.However, reproducing the behavior of anatomical structures remains a complex task, and a great amount and variety of knowledge is necessary for setting up high quality simulations.This makes the modeling of human body for simulation purposes an open problem, a tedious task, but also a fascinating research subject.Through this PhD, we address the problem of the construction of biomechanical models of the musculoskeletal systems for several domains : animation, biomechanics and teaching.Our goal is to simplify the entire process of model design by making it more intuitive and faster.Our approach is to address each difficulty : the representation and use of anatomical knowledge, the geometrical modeling and the efficient simulation of the musculoskeletal system thanks to three novel contributions introduced during these research works.Our first contribution focuses on the biomechanical construction of a hybrid model of lumbar spine.In this work, we show that hybrid approaches that combine both rigid body systems and finite element models allow interactive simulations, accurate, while respecting the principles of anatomy and mechanics.Our second contribution addresses the problem of the complexity of anatomical, physiological and functional knowledge.Based on a novel ontology of anatomical functions of the human body, we introduce a novel pipeline to automatically build models that simulate physiological functions of our bodies.The ontology allows us to extract detailed knowledge using simple queries.The outputs of these queries are used to set up simulation models of the functional aspects as they were formalized and described by anatomists.Finally our third contribution, the anatomy transfer, allows the mapping of available geometrical and mechanical models to the morphology of any specific individual.This novel registration method enables the automatic construction of the internal anatomy of any character defined by his skin, by transferring organs from a reference character.It allows to overcome the need to re-construct these geometries for each new simulation, and it contributes to accelerate the simulations setup for a range of people with different morph

Doctor en Ingeniería Eléctrica
Durante una neurocirugía se debe contar con información anatómica precisa, la cual es comúnmente obtenida por medio de un registro entre la posición del paciente y datos pre-operatorios. Uno de los principales problemas para realizar este registro es la deformación del cerebro durante la cirugía, fenómeno conocido como Brain Shift. Para solucionar este problema se han creado modelos mecánicos del cerebro, con los cuales es posible aproximar la deformación real. Estos modelos mecánicos requieren un modelo anatómico del paciente, el cual se obtiene, en la mayor parte de los casos, por medio de una segmentación manual o semi-manual. El objetivo de esta tesis es mejorar la obtención del modelo anatómico, proponiendo un método automático para obtener un modelo anatómico del cerebro, adaptado a la anatomía particular del paciente y adecuado para un posterior modelamiento mecánico. El método propuesto realiza una pre-segmentación del cerebro, seguida de una segmentación basada en modelos deformables para identificar las estructuras anatómicas más relevantes para el modelamiento mecánico. Se incluyen las estructuras comúnmente utilizadas en la literatura: superficie cortical, superficie interna del cráneo y ventrículos. Además, se incluyen las membranas internas del cerebro: falx cerebri y tentorium cerebelli. Estas membranas se han incorporado en los modelos de muy pocas publicaciones, aun cuando su importancia es reconocida en la literatura. La segmentación por modelos deformables que se ha implementado está principalmente basada en mallas simplex, las cuales son duales topológicos de las mallas de triángulos. Para aprovechar las cualidades complementarias de estas dos representaciones, se ha desarrollado un nuevo método de transformación entre ellas. Nuestro método usa una interpolación geométrica basada en la distancia a los planos tangentes a los vértices de las mallas. El método de transformación fue evaluado usando mallas estándar y obtuvo excelentes resultados al compararlo con el método actualmente más usado, el cual emplea el centro de gravedad de las caras de las mallas. En nuestro método de segmentación las estructuras son segmentadas de manera secuencial y respetando las relaciones anatómicas entre ellas. La segmentación obtenida fue evaluada empleando las bases de datos en linea más usadas (BrainWeb, IBSR, SVE). La segmentación de cada estructura fue evaluada de manera independiente y se realizaron algunas comparaciones con métodos de segmentación populares y establecidos, obteniendo resultados superiores. Las segmentaciones de la superficie cortical, la superficie interna del cráneo y los ventrículos fueron evaluadas usando los indices de Jaccard (J) y Dice (κ). Los resultados para la superficie cortical fueron: J = 0,904 y κ = 0,950 en BrainWeb; J = 0,902 y κ = 0,948 en IBSR; J = 0,946 y κ = 0,972 en SVE. Los resultados para la superficie interna del cráneo fueron J = 0,945 y κ = 0,972 en BrainWeb. Los resultados para los ventrículos fueron: J = 0,623 y κ = 0,766 en IBSR. Las segmentaciones de las membranas internas del cerebro fueron evaluadas midiendo la distancia entre nuestra segmentación y la posición estimada de las membranas en la base de datos IBSR. La distancia media para el tentorium cerebelli fue 1,673 mm, y para el falx cerebri fue 0,745 mm.

Improved knowledge of human nerve function and recruitment would enable innovation in the Biomedical Engineering field. Better understanding holds the potential for greater integration between devices and the nervous system as well as the ability to develop therapeutic devices to treat conditions affecting the nervous system. This work presents a three-dimensional volume conductor model of the human arm for coupling with code describing nerve membrane characteristics. The model utilizes an inhomogeneous medium composed of bone, muscle, skin, nerve, artery, and vein. Dielectric properties of each tissue were collected from the literature and applied to corresponding material subdomains. Both a fully anatomical version and a simplified version are presented. The computational model for this study was developed in COMSOL and formatted to be coupled with SPICE netlist code. Limitations to this model due to computational power as well as future work are discussed. The final model incorporated both anatomically correct geometries and simplified geometries to enhance computational power. A stationary study was performed implementing a boundary current source through the surface of a conventionally placed electrode. Results from the volume conductor study are presented and validated through previous studies.

Thesis (Ph. D.)--University of California, Riverside, 2009.
Includes abstract. Title from first page of PDF file (viewed January 28, 2010). Available via ProQuest Digital Dissertations. Includes bibliographical references (p. 100-106).

Background: Experimental mapping and computer modelling provide important platforms to study the fundamental mechanisms underlying normal and abnormal activation of the heart. However, accurate computer modelling requires detailed anatomical models and needs support and validation from experimental data. Aims: 1) Construction of detailed anatomical heart models with the cardiac conduction system (CCS). 2) Mapping of the electrical activation sequence in rabbit atria to support and validate computer simulation. 3) Mapping of the spontaneous activity in the atrioventricular ring tissues (AV rings), which consist of nodal-like myocytes and can be a source of atrial tachycardia. Methods: High-resolution magnetic resonance imaging (MRI) and computed tomography (CT) were used to provide two-dimensional (2D) images for the construction of the detailed anatomical heart models. Immunohistochemistry and Masson’s trichrome staining were used to distinguish the CCS in the heart. LabVIEW was used in the development of a multi-electrode mapping system. The multi-electrode mapping technique was employed to map the electrical activation sequence of the rabbit atria. The cellular automaton model was used to simulate electrical activation of the rabbit atria. Results: 1) Three detailed anatomical models were constructed, including a detailed three dimensional (3D) anatomical model of the rabbit heart (whole of the atria and part of the ventricles), a 3D anatomical model of the rat heart with the CCS and AV rings, and a 3D anatomical model of the human atrioventricular node. 2) A multi-electrode mapping system was developed. 3) The electrical activation sequence of the rabbit atria was mapped in detail using the multi-electrode mapping system. The conduction velocity in the rabbit atria was measured. The mapping data showed the coronary sinus and the left superior vena cava do not provide an interatrial conduction route during sinus rhythm in the rabbit heart. 4) Electrical activation of the rabbit atria was simulated with the support of the 3D anatomical model of the rabbit atria and the experimental mapping data. 5) The spontaneous activity in the rat AV rings was mapped using the multi-electrode mapping system. Conclusions: The detailed anatomical models developed in this study can be used to support accurate computer simulation and can also be used in anatomical teaching and research. The experimental mapping data from the rabbit atria can be used to support and validate computer simulation. The computer simulation study demonstrated the importance of anatomical structure and electrophysiological heterogeneity. This study also demonstrated that the AV rings could potentially act as ectopic pacemakers.

Simulation, in its many forms, has been a part of nursing education and practice for many years. The use of games, computer-assisted instruction, standardized patients, virtual reality, and low-fidelity to high-fidelity mannequins have appeared in the past 40 years, whereas anatomical models, partial task trainers, and role playing were used earlier. A historical examination of these many forms of simulation in nursing is presented, followed by a discussion of the roles of simulation in both nursing education and practice. A viewpoint concerning the future of simulation in nursing concludes this article.

L'imagerie par résonance magnétique du processus de diffusion (IRMd) de l'eau dans le cerveau a connu un succès fulgurant au cours de la décennie passée pour cartographier les connexions cérébrales. C'est toujours aujourd'hui la seule technique d'investigation de la connectivité anatomique du cerveau humain in vivo. Mais depuis quelques années, il a été démontré que l'IRMd est également un outil unique de biopsie virtuelle in vivo en permettant de sonder la composition du parenchyme cérébral également in vivo. Toutefois, les modèles développés à l'heure actuelle (AxCaliber, ActiveAx, CHARMED) reposent uniquement sur la modélisation des membranes axonales à l'aide de géométries cylindriques, et restent trop simplistes pour rendre compte précisément de l'ultrastructure de la substance blanche et du processus de diffusion dans l’espace extra-axonal. Dans un premier temps, un modèle analytique plus réaliste de la substance blanche cérébrale tenant compte notamment de la dépendance temporelle du processus de diffusion dans le milieu extra-axonal a été développé. Un outil de décodage complexe permettant de résoudre le problème inverse visant à estimer les divers paramètres de la cytoarchitecture de la substance blanche à partir du signal IRMd a été mis en place en choisissant un schéma d'optimisation robuste pour l'estimation des paramètres. Dans un second temps, une approche Big Data a été conduite pour améliorer le décodage de la microstructure cérébrale. Un outil de création de tissus synthétiques réalistes de la matière blanche a été développé, permettant de générer très rapidement un grand nombre de voxels virtuels. Un outil de simulation ultra-rapide du processus de diffusion des particules d'eau dans ces voxels virtuels a ensuite été mis en place, permettant la génération de signaux IRMd synthétiques associés à chaque voxel du dictionnaire. Un dictionnaire de voxels virtuels contenant un grand nombre de configurations géométriques rencontrées dans la matière blanche cérébrale a ainsi été construit, faisant en particulier varier le degré de gonflement de la membrane axonale qui peut survenir comme conséquence de pathologies neurologiques telles que l’accident vasculaire cérébral. L'ensemble des signaux simulés associés aux configurations géométriques des voxels virtuels dont ils sont issus a ensuite été utilisé comme un jeu de données permettant l'entraînement d'un algorithme de machine learning pour décoder la microstructure de la matière blanche cérébrale à partir du signal IRMd et estimer le degré de gonflement axonal. Ce décodeur a montré des résultats de régression encourageants sur des données simulées inconnues, montrant le potentiel de l’approche computationnelle présentée pour cartographier la microstructure de tissus cérébraux sains et pathologiques in vivo. Les outils de simulation développés durant cette thèse permettront, en utilisant un algorithme de recalage difféomorphe de propagateurs de diffusion d’ensemble également développé dans le cadre de cette thèse, de construire un atlas probabiliste des paramètres microstructuraux des faisceaux de matière blanche
Diffusion Magnetic Resonance Imaging of water in the brain has proven very useful to establish a cartography of brain connections. It is the only in vivo modality to study anatomical connectivity. A few years ago, it has been shown that diffusion MRI is also a unique tool to perform virtual biopsy of cerebral tissues. However, most of current analytical models (AxCaliber, ActiveAx, CHARMED) employed for the estimation of white matter microstructure rely upon a basic modeling of white matter, with axons represented by simple cylinders and extra-axonal diffusion assumed to be Gaussian. First, a more physically plausible analytical model of the human brain white matter accounting for the time-dependence of the diffusion process in the extra-axonal space was developed for Oscillating Gradient Spin Echo (OGSE) sequence signals. A decoding tool enabling to solve the inverse problem of estimating the parameters of the white matter microstructure from the OGSE-weighted diffusion MRI signal was designed using a robust optimization scheme for parameter estimation. Second, a Big Data approach was designed to further improve the brain microstructure decoding. All the simulation tools necessary to construct computational models of brain tissues were developed in the frame of this thesis. An algorithm creating realistic white matter tissue numerical phantoms based on a spherical meshing of cell shapes was designed, enabling to generate a massive amount of virtual voxels in a computationally efficient way thanks to a GPU-based implementation. An ultra-fast simulation tool of the water molecules diffusion process in those virtual voxels was designed, enabling to generate synthetic diffusion MRI signal for each virtual voxel. A dictionary of virtual voxels containing a huge set of geometrical configurations present in white matter was built. This dictionary contained virtual voxels with varying degrees of axonal beading, a swelling of the axonal membrane which occurs after strokes and other pathologies. The set of synthetic signals and associated geometrical configurations of the corresponding voxels was used as a training data set for a machine learning algorithm designed to decode white matter microstructure from the diffusion MRI signal and estimate the degree of axonal beading. This decoder showed encouraging regression results on unknown simulated data, showing the potential of the presented approach to characterize the microstructure of healthy and injured brain tissues in vivo. The microstructure decoding tools developed during this thesis will in particular be used to characterize white matter tissue microstructural parameters (axonal density, mean axonal diameter, glial density, mean glial cells diameter, microvascular density ) in short and long bundles. The simulation tools developed in the frame of this thesis will enable the construction of a probabilistic atlas of the white matter bundles microstructural parameters, using a mean propagator based diffeomorphic registration tool also designed in the frame of this thesis to register each individual

Dans les nouveaux protocoles thérapeutiques par voie inhalée, le dosage des particules actives reste un problème complexe qui dépend de trois principaux facteurs : leur taille, la dynamique des flux et les variations de calibre bronchique. La solution nécessite de disposer d'un modèle de distribution des gaz et aérosols administrés dans les poumons. Ventilation pulmonaire et effets du cycle respiratoire sur la dynamique des fluides deviennent deux enjeux clés de la pratique clinique.

Dans ce contexte, le projet RNTS RMOD a pour objectif de développer un simulateur morpho-fonctionnel des voies respiratoires pour l'aide au diagnostic, au geste médico-chirurgical et à l'administration de médicaments par inhalation.

Contribuant au projet RMOD, la recherche développée dans cette thèse propose une modélisation in-silico de la structure des voies aériennes supérieures (VAS) et proximales (VAP) à partir d'examens tomodensitométriques (TDM). L'investigation morphologique et la simulation fonctionnelle bénéficient alors de géométries 3D réelles, adaptées au patient et spécifiques des pathologies rencontrées.

La modélisation développée fait coopérer des méthodes originales de segmentation, de construction de surface maillée et d'analyse morpho-fonctionnelle.

La segmentation des VAP est obtenue par un schéma diffusif et agrégatif gouverné par un modèle markovien, dont l'initialisation repose sur l'opérateur de coût de connexion sous contrainte topographique. De cette segmentation, l'axe central de l'arbre bronchique est extrait de manière robuste et précise en combinant information de distance, propagation de fronts, et partition conditionnelle locale. Cet axe central est représenté sous forme d'une structure hiérarchique multivaluée synthétisant caractéristiques topologiques et géométriques de l'arbre bronchique. Une surface maillée est ensuite construite en appliquant une procédure de Marching Cubes adaptative, les paramètres des différents filtres mis en jeu étant automatiquement ajustés aux caractéristiques locales du réseau bronchique conditionnellement aux attributs de l'axe central.

La segmentation des VAS repose sur une propagation markovienne exploitant les variations locales de densité. L'initialisation combine morphologie mathématique et information de contour afin de garantir la robustesse à la topologie. Une procédure de type triangulation de Delaunay restreinte à une surface fournit ensuite la représentation maillée des VAS. Il est établi que la topologie et la géométrie des structures complexes composant les VAS sont effectivement préservées.

Pour permettre aux médecins de valider les modèles maillés ainsi construits, un environnement virtuel 3D convivial et interactif a été réalisé. En outre, la morphologie des voies aériennes exo- et endo-luminale est analysée de façon automatique à partir de simulations d'écoulement pour des géométries réelles.

Enfin, une modélisation unifiée des VAP et VAS est obtenue pour la première fois. Elle démontre la pertinence des approches développées. Elle ouvre la voie à la construction de modèles in-silico complets de l'appareil respiratoire ainsi qu'aux études fonctionnelles prenant en compte les paramètres morphologiques susceptibles d'influer localement ou globalement sur la dynamique des écoulements.

Os métodos de controle de qualidade tradicionais aplicados ao radiodiagnóstico, é a melhor maneira de garantir a boa qualidade das imagens produzidas. No entanto, a investigação de particularidades oriundas do processo de formação de imagens radiológicas requer ferramentas computacionais complementares, em função do número de variáveis envolvidas. Entretanto, os fantomas computacionais baseados em voxels não conseguem representar as variações morfométricas necessárias para a simulação de exames cujo diagnóstico é baseado em imagem. Neste trabalho foi desenvolvido um novo tipo de fantoma computacional, baseado em modelagem 3D, que possui as vantagens apresentadas pelos fantomas computacionais tradicionais sem os problemas encontados nestes. A ferramenta de modelagem utilizada, o Blender, é disponibilizada gratuitamente na internet. A técnica utilizada foi a box modeling, que consiste na deformação de uma primitiva básica, nesse caso um cubo, até que apresente a forma da estrutura que se deseja modelar. Para tanto, foram utilizadas como referencia, imagens obtidas de atlas de anatomia e fotografias de um esqueleto fornecido pela Universidade de Mogi das Cruzes. Foram modelados o sistema ósseo, os órgãos internos e a anatomia externa do corpo humano. A metodologia empregada permitiu a alteração de parâmetros do modelo dentro da ferramenta da modelagem. Essa possibilidade foi mostrada através da variação, dos formatos do intestino e do aumento da quantidade de tecido adiposo da malha referente a pele. A simulação das imagens radiológicas foi realizada a partir de coeficientes de atenuação de massa de materiais, ossos e tecidos e de modelos com diversas características físicas. Essa versatilidade permite prever a influência que as diferenças morfométricas entre os indivíduos provocam nas imagens, propriciando dessa forma, uma ferramenta relevante complementar aos métodos de controle de qualidade tradicionais.
The conventional methods of quality control applied to radio diagnosis are the best way to have assured good quality of the produced images. Due the amount of variables to consider, the study of particular issues of the process of formation of radiological images requires complementary computational tools. However, the computational voxel based phantoms are not suitable to represent the morphometrical variations, intended for test simulations with image based diagnosis. This work developed a new type of computational phantom, based on 3D modelling. It has the same advantages of the conventional ones, without some of their restrictions. The modeling tool employed, Blender, is available on internet for free download. The project uses the technique called box modeling, which consists in the deformation of a primitive form (a cube, in this case) until it presents a similar form to that it is wanted to model. In order to achieve it, some images, obtained from anatomy atlas and a skeleton pictures obtained from University of Mogi das Cruzes, were used as reference. Were built models from skeletal system, internal organs and external human body anatomy. The applied methodology allowed model´s parameter settings on the modelling tool. This option was presented by means of intestine format variation and increase of adipose tissue on the mesh that represents skin. The simulation of radiological images was done by means of x-ray mass attenuation coefficients, bones and tissues and models with diferent physical characteristics. This flexibility allows the analysis and forecasting of the influences that morphometrical differences of individual implies on images, revealing an important tool that complements the conventional quality control tools.

Introdução: Universidades e hospitais solicitam alternativas para o uso de animais no treinamento médico sempre que possível. O custo dos manequins artificiais atualmente aprovados pelo Colégio Americano de Cirurgiões muitas vezes torna o seu uso proibitivo em países em desenvolvimento e subdesenvolvidos. Um manequim artificial de baixo custo (SurgeMan®) foi desenvolvido no Brasil. Nosso objetivo primário foi determinar se o SurgeMan® é adequado de acordo com o grau de satisfação dos alunos e instrutores do programa ATLS® quando comparado com o modelo TraumaMan® e o modelo animal, que são os atualmente aprovados para os procedimentos cirúrgicos do curso. Nosso objetivo secundário foi determinar se os índices de satisfação do usuário para SurgeMan® são superiores a 80%. Métodos: Foi realizado um estudo cruzado prospectivo com três modelos. Foram utilizados os modelos: SurgeMan® (SMan), TraumaMan® (TMan) e um modelo animal (suínos da raça Landrace). Uma amostra de conveniência de 36 estudantes candidatos a alunos do curso ATLS® foi alocada em nove grupos de quatro alunos e monitorados por um instrutor durante toda a estação de atividades cirúrgicas. Cada grupo participou de todas as atividades cirúrgicas em cada um dos três modelos. Os procedimentos realizados foram: drenagem pleural, cricotireoidostomia, pericardiocentese e lavagem peritoneal diagnóstica (DPL). Os testes psicométricos foram concluídos com os alunos e instrutores preenchendo um questionário com escala de Likert na conclusão de cada atividade. Os estudantes e instrutores também foram questionados sobre a adequação dos modelos para a realização da prática de atividades cirúrgicas do curso ATLS®, se eles substituiriam ou não o modelo animal pelo SurgeMan® ou pelo TraumaMan® e sobre suas preferencias de modelo considerando aspectos éticos e financeiros e sem levar estes em consideração. Resultados: O modelo animal e TraumaMan® tiveram desempenho melhor do que SurgeMan® para todas as habilidades, exceto pericardiocentese, onde não houve diferença estatística entre os modelos (Anova para medidas repetidas). Quando fatores éticos e financeiros não foram levados em consideração: 58% dos alunos e 66% dos instrutores escolheram o modelo animal. Quando os fatores éticos e financeiros foram considerados os modelos foram igualmente recomendados pelos alunos (SMan.33%, TMan 30%, Suínos 33%) e os instrutores escolheram o SurgeMan® como primeira opção (SMan 66%, TMan 22%, Suínos 11%). Para a adequação de cada modelo para o aprendizado de habilidades no ATLS®, os alunos consideraram todos adequados (81% S.Man; 94% T.Man; 86% suínos; p = 0,184) e os instrutores consideraram apenas o modelo animal abaixo de 80% (SMan 88%, TMan 100%, Suínos 77%). Conclusão: TraumaMan® teve desempenho melhor do que SurgeMan® na maioria dos procedimentos. Os alunos consideram que tanto TraumaMan® quanto SurgeMan® são aceitáveis para a aprendizagem das habilidades cirúrgicas do ATLS®
Introduction: Universities and hospitals require the use of suitable alternatives to animals for training wherever possible. The cost of the currently approved artificial mannequins often makes their use prohibitive in low-income countries. A low cost Brazilian artificial mannequin (SurgeMan®) has been developed. Our primary objective was to determine whether SurgeMan® would have equivalent learner and instructor satisfaction scores compared with the currently approved TraumaMan® and an animal model for the surgical procedures of Advanced Trauma Life Support ATLS®. Our secondary objective was to determine if user satisfaction scores for the SurgeMan® exceeded 80%. Methods: This was a prospective crossover cohort study with 3 models, SurgeMan® (SMan), TraumaMan® (TMan), and an animal model (Landrace pigs). A convenience sample of 36 students enrolled in ATLS® courses was divided into 9 groups, which were monitored by 1 instructor per group throughout the skills station rotations. Each group participated in all skills in each of the 3 models. The procedures performed were tube thoracostomy, cricothyroidotomy, pericardiocentesis, and diagnostic peritoneal lavage (DPL). Psychometric testing was completed by having students and instructors fill out a Likert Scale at the completion of each activity. Students and instructors were also asked about the adequacy of the models for performing the surgical skills, if they would or would not substitute the animal model for the SurgeMan® or the TraumaMan®, and about their preferred model, with and without ethical and financial issues. Results: The animal model and the TraumaMan® performed better than the SurgeMan® for all skills except pericardiocentesis, where there was no difference in the models. When no ethical or financial factors were taken in consideration, 58% of the students and 66% of the instructors chose pigs as their preferred model. When all ethical factors were considered, all students equally recommended the models (SMan 33%, TMan 30%, pigs 33%) and the SurgeMan® was the first choice for the instructors (SMan 66%, TMan 22%, pigs 11%). The students thought all models were adequate for learning ATLS® skills (SMan 81%, TMan 94%, pigs 86%). The Instructors scored only the animal model under 80% (SMan 88%, TMan 100%, pigs 77%) for learning those skills. Conclusion: The TraumaMan® performed better than the SurgeMan® in most procedures. Students and instructors found that both the TraumaMan® and the SurgeMan® are acceptable for learning and teaching ATLS® surgical skills

Doutoramento em Engenharia Mecânica
A cortiça é um material celular natural capaz de suster quantidades consideráveis de energia. Estas características tornam este material ideal para determinadas aplicações como a proteção de impactos. Considerando equipamentos de segurança passiva pessoal, os materiais sintéticos são hoje em dia os mais utilizados, em particular o poliestireno expandido. Este também é capaz de absorver razoáveis quantidades de energia via deformação permanentemente. Por outro lado, a cortiça além de ser um material natural, é capaz de recuperar grande parte da sua forma após deformada, uma característica desejada em aplicações com multi-impacto. Neste trabalho é efetuada uma avaliação da aplicabilidade da cortiça em equipamentos de segurança pessoal, especificamente capacetes. Vários tipos de cortiça aglomerada foram caracterizados experimentalmente. Impactos foram simulados numericamente para avaliar a validade dos modelos constitutivos e as propriedades utilizadas para simular o comportamento da cortiça. Capacetes foram selecionados como caso de estudo, dado as energias de impacto e repetibilidade de impactos a que estes podem ser sujeitos. Para avaliar os capacetes de um ponto de vista biomecânico, um modelo de cabeça humana em elementos finitos foi desenvolvido. Este foi validado de acordo com testes em cadáveres existentes na literatura. Dois modelos de capacete foram modelados. Um modelo de um capacete rodoviário feito de materiais sintéticos, o qual se encontra disponível no mercado e aprovado pelas principais normas de segurança de capacetes, que serve de referência. Este foi validado de acordo com os impactos da norma. Após validado, este foi avaliado com o modelo de cabeça humana em elementos finitos e uma análise ao risco de existência de lesões foi efetuado. Com este mesmo capacete, foi concluído que para incorporar cortiça aglomerada, a espessura teria de ser reduzida. Então um novo modelo de capacete foi desenvolvido, sendo este uma espécie de modelo genérico com espessuras constantes. Um estudo paramétrico foi realizado, variando a espessura do capacete e submetendo o mesmo a duplos impactos. Os resultados destes impactos e da análise com o modelo de cabeça indicaram uma espessura ótima de 40 mm de cortiça aglomerada, com a qual o capacete tem uma melhor resposta a vários impactos do que se feito de poliestireno expandido.
Cork is a natural cellular material capable of withstanding considerable amounts of energy. These features make it an ideal material for some applications, such as impact protection. Regarding personal safety gear, synthetic materials, particularly expanded polystyrene, are typically used. These are also able to absorb reasonable amounts of energy by deforming permanently. On the other hand, in addition to cork being a natural material, it recovers almost entirely after deformation, which is a desired characteristic in multi-impact applications. In this work, the applicability of agglomerated cork in personal safety gear, specifically helmets, is analysed. Different types of agglomerated cork were experimentally characterized. These experiments were simulated in order to assess the validity of the constitutive models used to replicate cork's mechanical behaviour. In order to assess the helmets from a biomechanical point of view, a finite element human head model was developed. This head model was validated by simulating the experiments performed on cadavers available in the literature. Two helmet models were developed. One of a motorcycle helmet made of synthetic materials, which is available on the market and certified by the main motorcycle helmets safety standards, being used as reference. This helmet model was validated against the impacts performed by the European standard. After validated, this helmet model was analysed with the human head model, by assessing its head injury risk. With this helmet, it was concluded that a thinner helmet made of agglomerated cork might perform better. Thus, a new helmet model with a generic geometry and a constant thickness was developed. Several versions of it were created by varying the thickness and subjecting them to double impacts. The results from these impacts and the analyses carried out with the finite element head model indicated an optimal thickness of 40 mm, with which the agglomerated cork helmet performed better than the one made of expanded polystyrene.

Als artistes l’estudi de l’anatomia els serveix, ens serveix, per entendre la relació entre la forma exterior i les estructures responsables de la creació d’aquesta forma. En aquest treball seguiré un enfocament similar en el desenvolupament de models basats en l'anatomia, especialment pel que fa als músculs i als ossos. Consideraré la influència de la musculatura en les formes superficials i desenvoluparé uns models de musculatura que s’adaptin automàticament als canvis de la postura d'un esquelet articulat subjacent que farà les funcions d’esquelet funcional. Els models s'implementaran en un llenguatge que ofereix uns mecanismes i procediments útils per definir i manipular models articulats de forma que a posteriori i amb un maquinari molt més potent també sigui aplicable a altres parts del cos humà no visibles (en el sentit d’afectables) des de la morfologia externa com poden ser el sistema limfàtic, el digestiu o el circulatori dels quals no se’n farà l’animació degut a la gran quantitat de recursos que es necessiten com a conseqüència de l’elevat nombre de polígons que contenen. Per mostrar el funcionament d’aquest procediment l’aplicaré en diverses situacions als dos models de figura humana realitzats en aquest treball. En aquesta tesi abordaré el procés de modelat d’un cos humà masculí sintètic i d’un de femení fent ús d’un software de representació tridimensional. L'objectiu final és la realització d'un model humà tridimensional d’home i d’un de dona amb la màxima fidelitat possible a la realitat. Els moviments i les animacions obtingudes amb ambdós models estaran sota llicència de Creative Commons per tal de fer viable els dos aspectes següents: 1. Que d’una banda aquests resultats puguin ser emprats pels estudiants d’arts en general i d’animació en particular per assolir coneixements anatòmics i poder així estudiar i analitzar postures i moviments que d’altra manera serien difícils de retenir. 2. Que en formar part d’una base de dades de moviments i estar aquests sota una llicència compartida tots ens puguem beneficiar de les aportacions que algú altre pugui també fer i incorporar a posteriori en aquesta base de dades. Aquest treball està estructurat en quatre capítols. En el Capítol I hi trobem una part introductòria on es detallen els antecedents històrics pel qu fa al procediment emprat, es justifica la realització del treball i es fa un repàs de les dues gransestructures, axial i apendicular, com a responsables de la major part de la geometria visible del cos humà El Capítol II fonamenta teòricament la creació de gràfics 3D en general, el sistema de modelat emprat tot comparant-lo amb els altres sistemes i el procés tècnic de riggejat i mapejat del models generats. En el Capítol III es detallen les característiques necessàries que han de reunir els esquelets funcionals per poder rebre animació de forma automatitzada i s’aplica l’animació a aquests a partir d’arxius MoCap. En el Capítol IV es detalla la implementació de les animacions en quatre simuladors 3D i es valoren les possibilitats que té cadascún i les funcionalitats que podrà fer servir l’usuari.

CAPES
Estudos realizados com cães apontam que dos grupos tumorais analisados, os de mama representam cerca de 25% a 50% dos tipos de tumores. Deste total, metade é considerado maligno. Apesar de representar um valor considerável de malignidade, estudos nesta área são poucos representativos e escassos na literatura. É de conhecimento que os tumores são causados por mudanças químicas e bioquímicas que ocorrem na célula. Atualmente, pesquisas são realizadas para entender o comportamento dessas alterações e por este motivo é de grande valia conhecer os elementos traço presentes nestes tecidos. Para esta finalidade a técnica mais empregada é a de ED-XRF (Fluorescência de Raios X de Dispersão de Energia), uma vez que é uma técnica analítica não destrutiva que permite determinar e quantificar a composição elementar das amostras, porém não identifica elementos com baixos números atômicos (menor que Z=10). Foram analisadas 56 amostras de tecido mamário canino benignas e malignas, fixadas em formalina a 10% tamponada e mantida à temperatura ambiente. Primeiramente para a quantificação dos elementos traço Ca, Fe, Cu e Zn foram determinadas as curvas de calibração de padrões diluídos em água, com concentrações de Ca, Fe, Cu e Zn, variando de 400 mg/kg a 35 mg/kg, de 20 mg/kg a 2 mg/kg, de 10 mg/kg a 1 mg/kg e de 100 mg/kg a 9 mg/kg, respectivamente. As medições foram submetidas à técnica de ED-XRF utilizando um tubo de raios X com ânodo de prata e técnica de exposição de 30 kV e 100uA e um tempo de exposição de 1000 segundos (incerteza ≤ 3%). O código XRMC (X-Ray Monte Carlo) foi utilizado para validação do método experimental, que tem o objetivo de simular computacionalmente as respostas esperadas para os ensaios experimentais validando assim a eficácia da metodologia. As concentrações dos elementos traço obtidas foram analisadas estatisticamente onde verificou-se uma variação significativa do elemento Zn, estando este presente em maior concentração no tecido mamário maligno do que no benigno. Este resultado pode estar relacionado à presença deste elemento nas matrizes de metaloproteinases, e em neoplasias malignas estão mais concentradas porque há característica de invasão tumoral neste tipo de neoplasia. Em outra comparação estatística pode-se verificar que os elementos traços Fe, Cu e Zn tem concentração equivalente tanto na região central do tumor tanto quanto na periferia, com exceção do Ca, este concentrando-se mais na região tumoral o que pode se dever às calcificações. Estudos nessa área são de grande potencial por permitir um melhor entendimento do processo patológico em tumores mamários caninos.
Studies with dogs show that the breast cancer represent about 25% to 50% of tumor types. Of this total, half is considered malignant. Despite representing a considerable amount of malignancy, studies in this area are few representative and scarce in the literature. It is known that tumors are caused by chemical and biochemical changes that occur in the cell. Currently, surveys are conducted to understand the behavior of these changes and for this reason, it is of great value to know the trace elements present in these tissues. For this purpose, the most common technique is to ED-XRF (X-Ray Fluorescence Energy Dispersion) since it is a non-destructive analytical technique to determine and quantify the elemental composition of the samples, although it doesn’t identify elements with low atomic numbers (less than Z= 10). Were analyzed 56 samples of canine breast tissue benign and malignant, fixed in 10% buffered formalin and kept at ambient temperature. First, for the measurement of trace elements Ca, Fe, Cu and Zn were determined standards for calibration curves diluted in water to concentrations of Ca, Fe, Cu and Zn, ranging from 400 mg/kg to 35 mg/kg, from 20 mg/kg to 2 mg/kg, from 10 mg/kg to 1 mg/kg and from 100 mg/kg to 9 mg/kg, respectively. Measurements were subjected to ED-XRF technique using an X-ray tube with silver anode and exposure technique of 30 kV and 100 uA and exposure time of 1000 seconds (uncertainty ≤ 3%). The XRMC code (X-Ray Monte Carlo) was used for validation of experimental method, which is intended to simulate by computer the expected responses for experimental tests, therefore validating the methodology efficiency. The concentrations of trace elements obtained were analyzed statistically where there was a significant variation of Zn element, the latter being present in higher concentration in malignant breast tissue than benign. This result may be related to the presence of this element in the matrix metalloproteinases, and malignant neoplasms are more concentrated because there are characteristic of tumor invasion in this type of neoplasm. In another statistical comparison it can be seen that the trace elements Fe, Cu and Zn is equivalent concentration both in the central region of the tumor as well as in the periphery, with the exception of Ca, this focusing more on the tumor region may be due to calcifications. Studies in this area are of great potential for allowing a better understanding of the disease process in canine mammary tumors.

La present tesi doctoral s’ha centrat en el repte d’aconseguir, mitjançant Fabricació Additiva (FA), models per a assaig quirúrgic, sota la premissa que els equips per fer-los haurien de ser accessibles a l’àmbit hospitalari. L’objectiu és facilitar l’extensió de l’ús dels prototips com a eina de preparació d’operacions quirúrgiques, transformant la pràctica mèdica actual de la mateixa manera que en el seu moment ho van fer tecnologies com les que van facilitar l’ús de radiografies. El motiu d’utilitzar FA, en lloc de tecnologies més tradicionals, és la seva capacitat de materialitzar de forma directa les dades digitals obtingudes de l’anatomia del pacient mitjançant sistemes d’escanejat tridimensional, fent possible l’obtenció de models personalitzats. Els resultats es centren en la generació de nou coneixement sobre com aconseguir equipaments d’impressió 3D multimaterials accessibles que permetin l’obtenció de models mimètics respecte als teixits vius. Per facilitar aquesta buscada extensió de la tecnologia, s’ha focalitzat en les tecnologies de codi obert com la Fabricació per Filament Fos (FFF) i similars basades en líquids catalitzables. La recerca s’alinea dins l’activitat de desenvolupament de la FA al CIM UPC, i en aquest àmbit concret amb la col·laboració amb l’Hospital Sant Joan de Déu de Barcelona (HSJD). El primer bloc de la tesi inclou la descripció de l’estat de l’art, detallant les tecnologies existents i la seva aplicació a l’entorn mèdic. S’han establert per primer cop unes bases de caracterització dels teixits vius -sobretot tous- per donar suport a la selecció de materials que els puguin mimetitzar en un procés de FA, a efectes de millorar l’experiència d’assaig dels cirurgians. El caràcter rígid dels materials majoritàriament usats en impressió 3D els fa poc útils per simular tumors i altres referències anatòmiques. De forma successiva, es tracten paràmetres com la densitat, la viscoelasticitat, la caracterització dels materials tous a la indústria, l’estudi del mòdul elàstic de teixits tous i vasos, la duresa d’aquests, i requeriments com l’esterilització dels models. El segon bloc comença explorant la impressió 3D mitjançant FFF. Es classifiquen les variants del procés des del punt de vista de la multimaterialitat, essencial per fer models d’assaig quirúrgic, diferenciant entre solucions multibroquet i de barreja al capçal. S’ha inclòs l’estudi de materials (filaments i líquids) que serien més útils per mimetitzar teixits tous. Es constata com en els líquids, en comparació amb els filaments, la complexitat del treball en processos de FA és més elevada, i es determinen formes d’imprimir materials molt tous. Per acabar, s’exposen sis casos reals de col·laboració amb l’HJSD, una selecció d’aquells en els que el doctorand ha intervingut en els darrers anys. L’origen es troba en la dificultat de l’abordatge d’operacions de resecció de tumors infantils com el neuroblastoma, i a la iniciativa del Dr. Lucas Krauel. Finalment, el Bloc 3 té per objecte explorar nombrosos conceptes (fins a 8), activitat completada al llarg dels darrers cinc anys amb el suport dels mitjans del CIM UPC i de l’activitat associada a treballs finals d’estudis d’estudiants de la UPC, arribant-se a materialitzar equipaments experimentals per validar-los. La recerca ampla i sistemàtica al respecte fa que s’estigui més a prop de disposar d’una solució d’impressió 3D multimaterial de sobretaula. Es determina que la millor via de progrés és la de disposar d’una pluralitat de capçals independents a fi de capacitar la impressora 3D per integrar diversos conceptes estudiats, materialitzant-se una possible solució. Cloent la tesi, es planteja com seria un equipament d’impressió 3D per a models d’assaig quirúrgic, a fi de servir de base per a futurs desenvolupaments.
La presente tesis doctoral se ha centrado en el reto de conseguir, mediante Fabricación Aditiva (FA), modelos para ensayo quirúrgico, bajo la premisa que los equipos para obtenerlos tendrían que ser accesibles al ámbito hospitalario. El objetivo es facilitar la extensión del uso de modelos como herramienta de preparación de operaciones quirúrgicas, transformando la práctica médica actual de la misma manera que, en su momento, lo hicieron tecnologías como las que facilitaron el uso de radiografías. El motivo de utilizar FA, en lugar de tecnologías más tradicionales, es su capacidad de materializar de forma directa los datos digitales obtenidos de la anatomía del paciente mediante sistemas de escaneado tridimensional, haciendo posible la obtención de modelos personalizados. Los resultados se centran en la generación de nuevo conocimiento para conseguir equipamientos de impresión 3D multimateriales accesibles que permitan la obtención de modelos miméticos respecto a los tejidos vivos. Para facilitar la buscada extensión de la tecnología, se ha focalizado en las tecnologías de código abierto como la Fabricación por Hilo Fundido (FFF) y similares basadas en líquidos catalizables. Esta investigación se alinea dentro de la actividad de desarrollo de la FA en el CIM UPC, y en este ámbito concreto con la colaboración con el Hospital Sant Joan de Déu de Barcelona (HSJD). El primer bloque de la tesis incluye la descripción del estado del arte, detallando las tecnologías existentes y su aplicación al entorno médico. Se han establecido por primera vez unas bases de caracterización de los tejidos vivos – principalmente blandos – para dar apoyo a la selección de materiales que los puedan mimetizar en un proceso de FA, a efectos de mejorar la experiencia de ensayo de los cirujanos. El carácter rígido de los materiales mayoritariamente usados en impresión 3D los hace poco útiles para simular tumores y otras referencias anatómicas. De forma sucesiva, se tratan parámetros como la densidad, la viscoelasticidad, la caracterización de materiales blandos en la industria, el estudio del módulo elástico de tejidos blandos y vasos, la dureza de los mismos, y requerimientos como la esterilización de los modelos. El segundo bloque empieza explorando la impresión 3D mediante FFF. Se clasifican las variantes del proceso desde el punto de vista de la multimaterialidad, esencial para hacer modelos de ensayo quirúrgico, diferenciando entre soluciones multiboquilla y de mezcla en el cabezal. Se ha incluido el estudio de materiales (filamentos y líquidos) que serían más útiles para mimetizar tejidos blandos. Se constata como en los líquidos, en comparación con los filamentos, la complejidad del trabajo en procesos de FA es más elevada, y se determinan formas de imprimir materiales muy blandos. Para acabar, se exponen seis casos reales de colaboración con el HJSD, una selección de aquellos en los que el doctorando ha intervenido en los últimos años. El origen se encuentra en la dificultad del abordaje de operaciones de resección de tumores infantiles como el neuroblastoma, y en la iniciativa del Dr. Lucas Krauel. Finalmente, el Bloque 3 desarrolla numerosos conceptos (hasta 8), actividad completada a lo largo de los últimos cinco años con el apoyo de los medios del CIM UPC y de la actividad asociada a trabajos finales de estudios de estudiantes de la UPC, llegándose a materializar equipamientos experimentales para validarlos. La investigación amplia y sistemática al respecto hace que se esté más cerca de disponer de una solución de impresión 3D multimaterial de sobremesa. Se determina que la mejor vía de progreso es la de disponer de una pluralidad de cabezales independientes, a fin de capacitar la impresora 3D para integrar diversos conceptos estudiados, materializándose una posible solución. Para cerrar la tesis, se plantea cómo sería un equipamiento de impresión 3D para modelos de ensayo quirúrgico, a fin de servir de base para futuros desarrollos.

A thesis submitted to the faculty of Engineering, University of the Witwatersrand, Johannesburg , in fulfillment of the requirements for the degree of Doctor of Philosophy. Johannesburg, November 1994
Organ function is often characterised using imaging techniques. In particular a tracer is often used which does not react with tissue, is low in concentration, follows body fluid flows and is distinguishable from the observed system and thus measurable. These requirements ensure linear characteristics of the tracer. In this thesis, these linear characteristics are used to develop a generalised mathematical theory to determine organ function from imaged tracer experiments. The theory is based on anatomical and physiological information for single and multiple input organs. [Abbreviated Abstract. Open document to view full version]
MT2018

Extracellular potentials due to firing of action potentials are computed around cortical neurons and populations of cortical neurons. These extracellular potentials are calculated as a sum of contributions from ionic currents passing through the cell membrane at various locations using Maxwell's equations in the quasi-static limit. These transmembrane currents are found from simulations of anatomically reconstructed cortical neurons implemented as multi-compartmental models in the simulation tool NEURON. Extracellular signatures of action potentials of single neurons are calculated both in the immediate vicinity of the neuron somas and along vertical axes. For the neuronal populations only vertical axis distributions are considered. The vertical-axis calculations were performed to investigate the contributions of action potential firing to laminar-electrode recordings. Results for high-pass (750 - 3000 Hz) filtered potentials are also given to mimic multi-unit activity (MUA) recordings. Extracellular traces from single neurons and populations (both synchronous and asynchronous) of neurons are shown for three different neuron types: layer 3 pyramid, layer 4 stellate and layer 5 pyramid cell. The layer 3 cell shows a 'closed-field' configuration, while the layer 5 pyramid demonstrates an 'open-field' appearance for singe neuron simulations which is less apparent in population simulations. The layer 4 stellate cell seems to fall somewhere in between the open- and closed-field scenarios. Comparing single neuron and synchronous populations, the amplitudes of the extracellular traces increase as population radii increase, though the shapes are generally similar. Asynchronous populations produce small amplitudes due to a time convolution of various neuron contributions.
Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005

PURPOSE: The purpose of this study was to analyze anatomical spatial limitations of the existing bone for maxillary anterior implant placement in normal subjects. MATERIALS AND METHODS: Fifty Two (52) Cone Beam Computed Tomography (CBCT) scans were selected. A 3i Osteotite (6 x 15mm) implant was superimposed on tooth positions from the right first premolar to left first premolar on reformatted cross sectional mages of maxillary anterior teeth. For the first trial, the implant was positioned following the alveolar bone axis. Utilizing Invivo 5 Software (Anatomage), the proximal overlaps between superimposed implants were evaluated at successive vertical steps of 2.5 mm. The prospective crown angulation or PCA (defined as the angulation between the crown axis and alveolar bone axis) was measured. The inter-canine distance across the arch, the palatal plane length and the palatal bony angulation (defined as the angulation between the palatal surface and the alveolar bone axis) were also measured. For the second trial, implant positioning followed a prosthetic driven position; the crown axis. The crown axis was defined as a line drawn from the midpoint of a line between the mid buccal/lingual CEJ to the incisal edge. The crest height and the apical height at which the implant's 1mm sleeve penetrated the buccal wall were calculated. RESULTS: The implant position at the central incisor and lateral incisor presented the highest percentage of overlap in both the biologically and prosthetically driven positions. The prospective crown angulation was higher at the location of the lateral incisor compared to the central incisor and canine position. The association between the remaining anatomical parameters and the prevalence of overlap was analyzed with bi-serial correlation. There was no significant relationship among any of these parameters. When the implant was simulated in a prosthetically driven position, the lateral incisor implant position frequently showed perforation at 5mm apical to the buccal crest margin demonstrating this position as highly sensitive. SUMMARY: The data demonstrated that the constriction of the alveolar bony volume in the anterior maxilla could affect implant placement. Understanding this bone morphology suggests a major limitation in the central/lateral positions which might require bone grafting. A new unique reference plane was utilized for this study.
2018-09-28T00:00:00Z