Choi Kup Sze. / "June 2004." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (p. 122-127). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

As a good and competent surgical simulator, it should provide surgeons with visual, tactile and behavioral illusion of reality. In literature, methods for object deformation range from non-physically based models to physically based models. Early works of non-physically based models focused on pure geometrical models that were originally employed in computer-aided design. These methods could be used to produce vivid deformable effects in computer animation. However, the soft tissue simulation in surgical applications requires more realistic models based on physical properties of human tissues. As a result, the mass-spring model and the finite element model have become the most popular representations for deformable organs in surgical simulation. Our research focuses on the real-time soft tissue deformable model based on the finite element method for surgical application. / Extended from the hybrid condensed finite element model, an interactive hybrid condensed model with hardware acceleration by the graphics processing unit (GPU) is proposed. Two methods are developed in order to map the data onto the GPU in accordance with the application data structure. The performance of the primary calculation task in the solver is enhanced. Furthermore, an improved scheme is presented to conduct the newly applied forces induced by dragging or poking operations in the non-operational region. / In the thesis, new approaches to establish a physically based model for soft tissue deformation and cutting in virtual-reality-based simulators are proposed. A deformable model, called the hybrid condensed finite element model, based on the volumetric finite element method is presented. By this method, three-dimensional organs can be represented as tetrahedral meshes, divided into two regions: the operational region and the non-operational one. Different methods treat the regions with different properties in order to balance the computational time and the level of the simulation realism. The condensation technique is applied to only involve the calculation of the surface nodes in the non-operational region while the fully calculation of the volumetric deformation is processed in the operational part. This model guarantees the smooth simulation of cutting operation with the exact cutting path when users manipulate a virtual scalpel. Moreover, we discuss the relevant aspects on what affect the efficiency of implementing the finite element method, as well as the issues considered for choosing the effective solving method to our problem. Three numerical methods have been examined in our model. / Surgical simulator, which benefits from virtual reality techniques, presents a realistic and feasible approach to train inexperienced surgeons within a safe environment. It plays more and more important role in medical field and also changes the world of surgical training. Especially, the minimally invasive microsurgery, which offers patients various attractive advantages over the traditional surgery, has been widely used in otolaryngology, gastroenterology, gynecology and neurology in the last two decades. / Through the combination of these approaches, a physically based model which allows users to freely perform the soft tissue cutting and detecting, such as poking or dragging operations, with soft tissue deformation is achieved in real-time. / Wu Wen. / "August 2006." / Adviser: Pheng Ann Heng. / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1745. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 112-127). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

by Lau Wan Yee, Joseph. / Thesis (M.D.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references (leaves 145-189). / Title Page --- p.1 / Dedication --- p.2 / Table of Contents --- p.3 / Hypotheses --- p.7 / Precis to the thesis --- p.8 / List of Publications of my research work used in this thesis --- p.19 / List of Figures --- p.25 / List of Tables --- p.26 / Acknowledgments --- p.27 / Statement of Originality --- p.28 / Chapter PART I --- HISTORICAL REVIEW --- p.30 / Chapter Chapter 1 --- History of Endoscopic and Laparoscopic Surgery --- p.31 / Chapter 1.1 --- History of Endoscopic Surgery --- p.31 / Chapter 1.2 --- History of Documentation of Endoscopic and Laparoscopic Surgery --- p.38 / Chapter 1.3 --- History of Laparoscopic Surgery --- p.39 / Chapter 1.4 --- The future of Endoscopic and Laparoscopic Surgery --- p.52 / Chapter Chapter 2 --- History of Perforated Peptic Ulcer --- p.53 / Chapter PART II --- SIZE OF THE PROBLEM --- p.57 / Chapter Chapter 1 --- Incidence of Feptic Ulcer in Different Parts of The World --- p.58 / Chapter Chapter 2 --- Incidence of Peptic Ulcer in Hong Kong 1970 -1993 --- p.60 / Chapter Chapter 3 --- Incidence of Perforated Peptic Ulcer --- p.70 / Chapter 3.1 --- Incidence of Perforated Peptic Ulcer in Different Parts of The World --- p.70 / Chapter 3.2 --- Incidence of Perforated Peptic Ulcer in Hong Kong --- p.71 / Chapter 3.3 --- "Incidence of Perforated Peptic Ulcer in Prince of Wales Hospital, Hong Kong" --- p.71 / Chapter PART III --- CURRENT TREATMENT OF PERFORATED PEPTIC ULCER --- p.74 / Chapter Chapter 1 --- Recent Developments in Treatment of Uncomplicated Peptic Ulcer --- p.75 / Chapter Chapter 2 --- My Contributions to the Medical Treatment of Uncomplicated Peptic Ulcer --- p.78 / Chapter Chapter 3 --- Review on Current Treatment of Perforated Peptic Ulcer --- p.79 / Chapter 3.1 --- Introduction --- p.79 / Chapter 3.2 --- Currently Available Treatment Options --- p.80 / Chapter 3.2.1 --- Perforated Duodenal Ulcer --- p.81 / Chapter [A] --- Nonoperative Treatment --- p.81 / Chapter [B] --- Laparotomy and patch repair --- p.83 / Chapter [C] --- Definitive Ulcer Surgery --- p.84 / Chapter [D] --- Laparoscopic Treatment --- p.87 / Chapter 3.2.2 --- Perforated Gastric Ulcer --- p.89 / Chapter PART IV --- DEVELOPMENT OF LAPAROSCOPIC REPAIR OF PERFORATED PEPTIC ULCER IN OUR CENTRE --- p.91 / Chapter Chapter 1 --- Development of the Technique of Laparoscopic Suture Repair of Perforated Peptic Ulcer --- p.92 / Chapter 1.1 --- Surgical Technique --- p.93 / Chapter 1.2 --- Initial Results of Laparoscopic Suture Repair --- p.95 / Chapter Chapter 2 --- Development of the Technique of Laparoscopic Sutureless Repair of Perforated Peptic Ulcer --- p.98 / Chapter 2.1 --- Animal Studies --- p.98 / Chapter [A] --- Pilot Animal Study --- p.99 / Chapter [B] --- Mortality Rate on Different Methods of Repair of the Perforations --- p.100 / Chapter [C] --- Strength of the Repair Site by Studying the Bursting Pressure --- p.103 / Chapter [D] --- Detailed Histological Study --- p.108 / Chapter 2.2 --- Clinical Studies --- p.111 / Chapter [A] --- Surgical technique of Laparoscopic Sutureless Repair --- p.113 / Chapter [B] --- Initial Results of Laparoscopic Sutureless Repair --- p.114 / Chapter PART V --- TESTING THE HYPOTHESES OF THIS THESIS --- p.117 / Chapter Chapter 1 --- A Non-randomised Clinical Study --- p.119 / Chapter Chapter 2 --- A Randomised Clinical Study --- p.126 / Chapter PART VI --- CONCLUSIONS --- p.140 / Chapter PART VII --- THE FUTURE OF LAPAROSCOPIC REPAIR OF PERFORATED PEPTIC ULCER --- p.142 / Chapter PART VIII --- REFERENCES --- p.145 / References to the Precis --- p.146 / References to Part I Chapter 1 --- p.147 / References to Part I Chapter2 --- p.157 / References to Part II --- p.162 / References to Part III --- p.168 / References to Part IV --- p.183 / References to Part V --- p.186 / References to Part VII --- p.189 / APPENDIX I BRIEF SUMMARY OF MY CONTRIBUTIONS TO THE MEDICAL TREATMENT OF UNCOMPLICATED PEPTIC ULCER --- p.190

Finally, the system of vascular interventional radiology simulator is discussed by integrating all presented techniques and designing a trackball mouse based hardware sensors. Training experiments demonstrate that the presented techniques benefit rapid development of realistic and interactive vascular interventional radiology simulators. / Fourth, in order to clearly visualize vascular networks and the placement of instruments while treating the lesion, a physics-based simulation for angiography procedure is presented based on navier-stokes equation and semi-lagrangian method. The multi-scale vessel grid is reconstructed for flow distribution, and point sprites based rendering is adopted to preserve real-time visualization of the procedure. The experiments demonstrate that our results are more realistic compared to previous methods and are closer to the real angiography procedure. / In order to build a high fidelity interventional simulator for physician training and surgery planning, accurate reconstruction of three dimensional vascular network, real-time simulation of angiographic medium propagation and physics-based simulation of interaction between surgical instruments and vessel wall are absolutely indispensable. Thus, first, a methodology for geometric vascular modeling is proposed. As the reconstructed models are essential for many subsequent applications such as deformable modeling and visualization, a series of methods are proposed based on the parallel transport frames in order to maintain high mesh quality of these models. An improved bifurcation modeling method and two novel trifurcation modeling methods are developed based on 3D Bezier curve segments in order to ensure the continuous surface transition at furcations. To solve the twisting problem caused by frame mismatch of two successive furcations, a frame blending scheme is implemented. A curvature based adaptive sampling scheme combined with a mesh quality guided frame tilting algorithm is developed to construct an evenly distributed, non-concave and self-intersection free surface mesh. In terms of surface mesh quality criteria, our methodology can generate vascular models with better mesh quality than previous methods. / Second, we extend our geometric modeling method for illustrative visualization of vasculature, which is an indispensable component in medical education and training. Illustration of vasculature accentuates depth perception and provides a specific manner to identify the branching pattern and topology of vascular structure, which is crucial for therapy planning and real surgery in order to give an effective treatment. With advanced GPU acceleration techniques including render to texture (RTT) , framebuffer object (FBO) and fast image convolution, a real-time visualization can be achieved. / Third, an interactive simulation of angioplasty procedure is reported. To achieve an efficient modeling of soft tissue deformation and virtual device mechanics, mass spring models are adopted to construct the deformable models of vessel wall and stent. By designing a quasi-equilateral triangular mesh model of blood vessel and stent, a linear spring coefficients setting method is adopted to achieve the same accuracy compared with finite element method. With the employment of Physics Processing Unit (PPU), a real-time simulation of the interaction between blood vessel wall and surgical device is developed for vascular interventional radiology simulation. / Vascular diseases have been the leading cause of death worldwide. Interventional procedures are an increasingly promising therapy for treating vascular diseases, which are usually done by a guidewire-catheter combination under the fluoroscopic guidance. However, due to the complicated vascular network, bending of surgical instruments and the risk of vessel injury, these techniques need to be performed by highly trained and experienced specialists. Virtual reality based training of these procedures offers high flexibility and cost effective alternative. Furthermore, it allows training evaluation and accelerates learning process without risk to patients, therefore has distinct advantages than traditional training methods on animals or cadavers. / Guo, Jixiang. / Advisers: Pheng-Ann Heng; Tien-Tsin Wong. / Source: Dissertation Abstracts International, Volume: 73-06, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 97-111). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Made available in DSpace on 2016-01-26T12:51:37Z (GMT). No. of bitstreams: 1 eumildodecampos junior_tese.pdf: 1761590 bytes, checksum: 07f0e6564f9169c180cc6baf09d6de84 (MD5) Previous issue date: 2011-12-16 / Dysphagia caused by chagasic megaesophagus compromises the clinical status and quality of life of patients. In this context, the Serra Dória s operation is a useful procedure in cases of advanced or recurrent disease. Little is known about the cardiovascular complications related to this surgery. Objective: This study aim to identify preoperative risk factors associated with cardiovascular complications after Serra Dória s operation in patients with megaesophagus caused by Chagas disease at the hospital period to document the data in order to better preoperative evaluating of these of these patients. Methods: This is a retrospective study evaluating patients who underwent the Serra Dória s operation at the General Surgery Service of Hospital de Base (FUNFARME), Faculty of Medicine of Sao Jose do Rio Preto (FAMERP) from 1998 to 2010. Initially, we assessed 103 medical records and excluded from the study 16 patients with idiopathic achalasia and 11 incomplete charts; therefore, the study population consisted of 76 patients with chagasic megaesophagus who underwent Serra Dória s procedure. The study was approved by the Ethics in Research Committee No. 254/2011. The following preoperative variables were included in the multivariate stepwise regression analysis: the model: age, sex, degrees of megaesophagus, operation for recurrence of symptoms, need for transfusion of red blood cells, blood pressure, electrolytes, comorbidities, electrocardiographic findings and degree of surgical risk. Cardiovascular complications were as follows: levels of hypotension and hypertension and cardiac arrhythmias without hemodynamic instability observed during the surgery and in the postoperative period. Student s t test was used in the comparison of continuous variables, whereas the chi-squared test was used in the comparison of categorical variables. Variables associated with the presence of cardiovascular complications at the p<0.05 were included in multivariate logistic stepwise regression. Those that remained associated with the presence of cardiovascular complications were considered independent variables to predict the appearance of cardiovascular complications. Results: The mean age was 61 ±10 years with male predominance (42, 55%). Most patients were classified as advanced megaesophagus (65, 86%); 36(47%) of them had relapsed megaesophagus. In 22(29%) of cases there was at least one comorbidity, with hypertension being the most frequently found (25, 30%). In 34(45%) patients the surgical risk was classified as moderate to severe. Among the electrocardiographic findings found preoperatively, sinus rhythm was found in 68(89%) patients, and right bundle-branch block in 28(37%). Cardiovascular complication was observed in 29(38%) patients, with prevalence of hypotension in various levels (14, 41%), followed by cardiac arrhythmias in 12(35%). The largest number of cardiovascular complications occurred during the immediate postoperative period. Variables associated with the presence of complications in the univariate model were age (p=0.003) and left bundle-branch block (p= 0.02). However, only the aged above 61 years of age was an independent predictor of cardiovascular complications in the postoperative Serra Dória s operation. Conclusion: Age is an independent predictor of cardiovascular complications following the Serra Dória s procedure. / A disfagia causada pelo megaesôfago chagásico compromete o estado geral e a qualidade de vida dos pacientes. Neste contexto, a cirurgia de Serra Dória é um procedimento útil nos casos avançados ou de recidiva da doença. Pouco se sabe a respeito das complicações cardiovasculares relativas a esta cirurgia. Objetivo: O estudo buscou identificar fatores de risco pré-operatórios associados às complicações cardiovasculares após a cirurgia de Serra Dória no período hospitalar para documentar os dados visando melhorar a avaliação pré-operatória destes pacientes. Casuística e Métodos: Estudo retrospectivo que analisou pacientes submetidos à cirurgia de Serra Dória no Serviço de Cirurgia Geral do Hospital de Base (FUNFARME) da Faculdade de Medicina de São Jose do Rio Preto (FAMERP) no período de 1998 a 2010. Inicialmente foram analisados 103 prontuários e excluídos do estudo 16 portadores de acalasia idiopática e 11 prontuários incompletos; portanto, a amostra consistiu de 76 pacientes portadores de megaesôfago chagásico submetidos à cirurgia de Serra Dória. O estudo foi aprovado pelo Comitê de Ética e Pesquisa parecer nº 254/2011. As seguintes variáveis pré-operatórias foram incluídas na análise de regressão logística multivariada passo-a-passo: idade, sexo, graus do megaesôfago, operação por recidiva dos sintomas, necessidade de transfusão de hemácias, níveis de pressão arterial, eletrólitos, comorbidades, achados eletrocardiográficos e grau de risco cirúrgico. As complicações cardiovasculares consideradas foram: níveis de hipotensão e hipertensão arterial e arritmias cardíacas com ou sem instabilidade hemodinâmica, observadas durante o período transoperatório, pós-operatório imediato e enfermaria. Para análise das variáveis contínuas utilizou-se o Test t de student não pareado, e para as variáveis descontínuas, o teste de qui-quadrado. Variáveis associadas à presença de complicações cardiovasculares com p <0,05 foram incluídas no modelo multivariado de regressão logística passo-a-passo. Aquelas que se mantiveram associadas à presença de complicações cardiovasculares foram consideradas variáveis de predição independente para o aparecimento dessas complicações. Resultados: A idade média da amostra foi de 61 ± 10 anos com predomínio do sexo masculino (42, 55%). A maioria dos pacientes apresentou megaesôfago avançado (65, 86%), e 36(47%) com recidiva dos sintomas que necessitaram de novo procedimento. Em 22(29%) dos casos houve pelo menos uma comorbidade, sendo a hipertensão arterial a mais frequente (25, 30%). O risco cirúrgico em 34(45%) pacientes foi considerado como moderado a grave. Nos achados eletrocardiográficos do pré-operatório, os mais frequentemente encontrados foram 68(89%) com ritmo sinusal seguido pelo bloqueio completo do ramo direito do feixe de His em 28(37%). Observou-se complicação cardiovascular em 29(38%) pacientes, com predomínio de hipotensão arterial em vários níveis (14, 41%), seguida de arritmias cardíacas em 12(35%). O maior número de complicações cardiovasculares ocorreu no período pós-operatório imediato. As variáveis associadas à presença de complicações no modelo univariado foram a idade (p=0,003) e o bloqueio de ramo esquerdo do feixe de His (p=0,02). No modelo multivariado, apenas a idade igual ou superior a 61 anos mostrou-se variável de predição independente para o aparecimento de complicações cardiovasculares no pós-operatório da cirurgia de Serra Dória. Conclusão: A idade é um fator de predição independente de complicações cardiovasculares após a cirurgia de Serra Dória.