Implicit models inherently support automatic blending and trivial collision detection which makes them an effective tool for designing complex organic shapes with many applications in various areas of research including surgical simulation systems. However, slow rendering speeds can adversely affect the performance of simulation and modelling systems. In addition, when the models are incorporated in a surgical simulation system, interactive and smooth cutting becomes a required feature for many procedures. In this research, we propose a comprehensive framework for high-performance rendering and physically-based animation of tissues modelled using implicit surfaces. Our goal is to address performance and scalability issues that arise in rendering complex implicit models as well as in dynamic interactions between surgical tool and models. Complex models can be created with implicit primitives, blending operators, affine transformations, deformations and constructive solid geometry in a design environment that organizes all these in a scene graph data structure called the BlobTree. We show that the BlobTree modelling approach provides a very compact data structure which supports the requirements above, as well as incremental changes and trivial collision detection. A GPU-assisted surface extraction algorithm is proposed to support interactive modelling of complex BlobTree models. Using a finite element approach we discretize those models for accurate physically-based animation. Our system provides an interactive cutting ability using smooth intersection surfaces. We show an application of our system in a human skull craniotomy simulation. / Graduate / 0984 / pourya.shirazian@gmail.com

The temporal bone is an anatomically complex region within the skull. Current training for temporal bone surgery includes cadaveric, physical and virtual haptic simulations and apprenticeships. Cadavers are limited by low supply. Haptic devices are limited by their force and stiffness ratings and thus cannot adequately simulate rigid materials. Physical simulations excel at simulating stiff materials but do a poor job of soft tissue. The research objective was to develop a mixed reality (MR) temporal bone surgical haptic simulation. This novel concept would utilize physical models to simulate bone and haptic forces to simulate soft tissue. A surgical drill was attached to a Quanser® High Definition Haptic DeviceTM (HD2) via a clamp. An algorithm was implemented to simulate a force at the drill tip and to negate the weight of the clamp. This modified haptic system was interfaced to a temporal bone haptic simulation. Haptic chatter unique to the modified haptic system was observed and low-pass filters were used to mitigate this issue. Due to the poor positional accuracy of the HD2, MR simulation was not achieved. However, VR haptic simulation was achieved. Six expert surgeons were recruited to investigate the following questions: "What is the impact of different haptic hardware on surgical realism?" and "Would end users prefer a surgical drill over a standard haptic manipulandum?" Three cases were compared: a Phantom Omni®, a standard HD2 and a modified HD2 with attached drill. Expert surgeons rated the standard HD2 and Phantom Omni equivalently whilst preferring the modified HD2 with attached drill. Though the modified HD2 scored higher in all categories only “Acoustics” and “Overall Appreciation” displayed statistical significance. This implies that drill acoustics is critical for realism. / February 2016

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Submitted by Maria Cristina (library@lncc.br) on 2017-05-04T16:14:48Z No. of bitstreams: 1 Dissertacao Leticia.pdf: 8187070 bytes, checksum: 9986568a293dff7d82ef96a704c5eeda (MD5) / Approved for entry into archive by Maria Cristina (library@lncc.br) on 2017-05-04T16:15:07Z (GMT) No. of bitstreams: 1 Dissertacao Leticia.pdf: 8187070 bytes, checksum: 9986568a293dff7d82ef96a704c5eeda (MD5) / Made available in DSpace on 2017-05-04T16:15:18Z (GMT). No. of bitstreams: 1 Dissertacao Leticia.pdf: 8187070 bytes, checksum: 9986568a293dff7d82ef96a704c5eeda (MD5) Previous issue date: 2017-02-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Capes) / Virtual Reality may be considered a computational tool often used to aid in medical training, specially in surgical training. That allows surgeons to gain dexterity and experience in surgery without risking real patient lifes, reducing the probability of medical errors to occur, henceforth providing a better quality of life to patients. Due to the fragility of the human eye, more than most other areas of medicine, ophthalmology can greatly benefit from surgical simulations. One of the most common surgeries in that field, cataract surgery is one of the most commonly performed. It increases the quality of life of the patient greatly, as it reestablishes their proper sight. This work introduces a cataract surgery simulator. The simulator uses a tactile device to increase its effectiveness.It provides the user with theoretic and practical knowledge. The simulator uses a serious game approach, containing four phases to be subdued. A set of interactive menus allow the user to control the procedure, which is actually performed through the tactile device (a Geomagic Touch). The user, henceforth, gains dexterity,which shall be useful in real life surgeries performed in the future. / A Realidade Virtual é uma ferramenta computacional utilizada para auxiliar na aprendizagem de procedimentos cirúrgicos na medicina, podendo minimizar erros cometidos pelos profissionais da área, e consequentemente, prover um melhor tratamento ao paciente. Devido à fragilidade do olho humano, dentre as áreas da medicina, a oftalmologia necessita da utilização da Realidade Virtual para treinar previamente um cirurgião inexperiente. Dentre as diversas cirurgias realizadas por oftalmologistas, o procedimento cirúrgico para o tratamento da acuidade visual denominada catarata, é considerado importante devido ao resultado positivo na qualidade de vida da população quando necessita ser realizada, além da incidência frequente da mesma na sociedade. Neste trabalho, foi desenvolvido um simulador de cirurgia de catarata com a utilização do dispositivo háptico Geomagic Touch, a fim de auxiliar estudantes de oftalmologia no treinamento teórico e prático da cirurgia denominada facoemulsificação. Para isto, o fenômeno no mundo real foi observado e suas características e eventos principais foram selecionados. Para este primeiro protótipo, algumas abstrações foram feitas para que o fenômeno pudesse ser representado computacionalmente. Assim, um serious game foi desenvolvido e a partir de fases e menus interativos, o usuário pode aprimorar seu conhecimento e aperfeiçoar sua destreza na manipulação dos equipamentos cirúrgicos.

The research presented in this thesis describes a substantial part of the design of a prototypical surgical training simulator. The results are intended to be applied in future simulators used to educate and train surgeons for bone milling operations. In earlier work we have developed a haptic bone milling surgery simulator prototype based on three degrees-of-freedom force feedback. The contributions presented here constitute an extension to that work by further developing the haptic algorithms to enable six degrees-of-freedom (6-DOF) haptic feedback. Such feedback is crucial for a realistic haptic experience when interacting in a more complex virtual environment, particularly in milling applications.The main contributions of this thesis are:The developed 6-DOF haptic algorithm is based on the work done by Barbic and James, but differs in that the algorithm is modified and optimized for milling applications. The new algorithm handles the challenging problem of real-time rendering of volume data changes due to material removal, while fulfilling the requirements on stability and smoothness of the kind of haptic applications that we approach. The material removal algorithm and the graphic rendering presented here are based on the earlier research. The new 6-DOF haptic milling algorithm is characterized by voxel-based collision detection, penalty-based and constraint-based haptic feedback, and by using a virtual coupling for stable interaction.Milling a hole in an object in the virtual environment or dragging the virtual tool along the surface of a virtual object shall generate realistic contact force and torque in the correct directions. These are important requirements for a bone milling simulator to be used as a future training tool in the curriculum of surgeons. The goal of this thesis is to present and state the quality of a newly developed 6-DOF haptic milling algorithm. The quality of the algorithm is confirmed through a verification test and a face validity study performed in collaboration with the Division of Orthopedics at the Karolinska University Hospital. In a simulator prototype, the haptic algorithm is implemented together with a new 6-DOF haptic device based on parallel kinematics. This device is developed with workspace, transparency and stiffness characteristics specifically adapted to the particular procedure. This thesis is focuses on the 6-DOF haptic algorithm. / QC 20120226

<p>A prototype of a haptic and virtual reality simulator has been developed for simulation of the bone milling and material removal process occurring in several operations, e.g. temporal bone surgery or dental milling. The milling phase of an operation is difficult, safety critical and very time consuming. Reduction of operation time by only a few percent would in the long run save society large expenses. In order to reduce operation time and to provide surgeons with an invaluable practicing environment, this licentiate thesis discusses the introduction of a simulator system to be used in both surgeon curriculum and in close connection to the actual operations.</p><p>The virtual reality and haptic feedback topics still constitute a young and unexplored area. It has only been active for about 10-15 years for medical applications. High risk training on real patients and the change from open surgery to endoscopic procedures have enforced the introduction of haptic and virtual reality simulators for training of surgeons. Increased computer power and the similarity to the successful aviation simulators also motivate to start using simulators for training of surgical skills.</p><p>The research focus has been twofold: 1) To develop a well working VR-system for realistic graphical representation of the skull itself including the changes resulting from milling, and 2) to find an efficient algorithm for haptic feedback to mimic the milling procedure using the volumetric Computer Tomography (CT) data of the skull. The developed haptic algorithm has been verified and tested in the simulator. The visualization of the milling process is rendered at a graphical frame rate of 30 Hz and the haptic rendering loop is updated at 1000 Hz. Test results show that the real-time demands are fulfilled. The visual and haptic implementations have been the two major steps to reach the over all goal with this research project.</p><p>A survey study is also included where the use of VR and haptic simulators in the surgical curriculum is investigated. The study starts with a historical perspective of the VR and haptic topics and is built up by answering different questions related to this topic and the implementation of simulators at the medical centres. The questions are of general concern for those developing surgical VR and haptic simulators.</p><p>Suggested future work includes modelling, development and validation of the haptic forces occurring in the milling process and, based on this, implementation in the simulator system. Also, further development of the simulator should be done in close cooperation with surgeons in order to get appropriate feedback for further improvements of the functionality and performance of the simulator.</p>

Mitral valve repair, the preferred method of treating mitral regurgitation, is a demanding surgical procedure consisting of the resection and approximation of valve tissue. Operating on an arrested heart, the clinician is forced to predict closed valve shape and the effect of surgical modifications. The valve's complex morphology makes this a difficult task, and as a result, the procedure is underperformed by less experienced surgeons in lieu of the simpler, less effective valve replacement. / Engineering and Applied Sciences

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A prototype of a haptic and virtual reality simulator has been developed for simulation of the bone milling and material removal process occurring in several operations, e.g. temporal bone surgery or dental milling. The milling phase of an operation is difficult, safety critical and very time consuming. Reduction of operation time by only a few percent would in the long run save society large expenses. In order to reduce operation time and to provide surgeons with an invaluable practicing environment, this licentiate thesis discusses the introduction of a simulator system to be used in both surgeon curriculum and in close connection to the actual operations. The virtual reality and haptic feedback topics still constitute a young and unexplored area. It has only been active for about 10-15 years for medical applications. High risk training on real patients and the change from open surgery to endoscopic procedures have enforced the introduction of haptic and virtual reality simulators for training of surgeons. Increased computer power and the similarity to the successful aviation simulators also motivate to start using simulators for training of surgical skills. The research focus has been twofold: 1) To develop a well working VR-system for realistic graphical representation of the skull itself including the changes resulting from milling, and 2) to find an efficient algorithm for haptic feedback to mimic the milling procedure using the volumetric Computer Tomography (CT) data of the skull. The developed haptic algorithm has been verified and tested in the simulator. The visualization of the milling process is rendered at a graphical frame rate of 30 Hz and the haptic rendering loop is updated at 1000 Hz. Test results show that the real-time demands are fulfilled. The visual and haptic implementations have been the two major steps to reach the over all goal with this research project. A survey study is also included where the use of VR and haptic simulators in the surgical curriculum is investigated. The study starts with a historical perspective of the VR and haptic topics and is built up by answering different questions related to this topic and the implementation of simulators at the medical centres. The questions are of general concern for those developing surgical VR and haptic simulators. Suggested future work includes modelling, development and validation of the haptic forces occurring in the milling process and, based on this, implementation in the simulator system. Also, further development of the simulator should be done in close cooperation with surgeons in order to get appropriate feedback for further improvements of the functionality and performance of the simulator. / QC 20101112