Master's Thesis - Studierstube Augmented Reality Project - Graz ...

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Chapter 4 Work-Flow and System Architecture This chapter introduces the necessary preprocessing steps before a visualization of PC- MRI datasets can be performed. Section 4.1 gives an overview of the requirements for an accurate visualization and the already available tools. Furthermore the desired software integrations ad combinations are proposed there. Subsequently, section 4.2 outlines the abilities of the Siemens Med 4D-Flow Toolbox [Reiter2006] which produces an intermediate result file for further processing. The parts of this file format which are necessary for this work are described in section 4.3 and appendix A. With these definitions a data reader can be implemented. The second part of this chapter, starting from section 4.4, deals with utilized tools and libraries. Finally, the programming environment and the medical image viewer iMEDgine are presented. iMEDgine was extended with hardware accelerated, visualization algorithms in this thesis. 4.1 Requirements Visualization of raw PC-MRI data, as they are described in chapter 3, requires preprocessing for aliasing corrections, baseline corrections and noise corrections. Therefore we used a toolkit (4D-Flow Toolbox) which we have developed for Siemens Medical Solutions in a previous project. The correction mechanisms of this toolkit are described in detail in section 4.2. For the resulting intermediate files, which are defined in section 4.3, we could subsequently elaborate the following requirements for a high-level 62
4.1 Requirements visualization of corrected four-dimensional velocity fields with additional medical image data. 1. After a measurement sequence, all resulting images are stored in the PACS 1 in the DICOM 2 format. Since only medical staff at facilities with PACS can access them, we decided to export them to DVD’s or CD’s. However, this implies that we need access to medical DICOM images and to the correlated DICOM-directories which are generated for exported datasets. An suitable interface is therefore the first requirement. 2. As already mentioned, most of the datasets need some preprocessing steps before a visualization can be done. With the 4D-Flow Toolbox it is possible to correct aliasing and baseline effects, to suppress noise and to draw segmentation contours. The resulting velocity field is not stored in the DICOM format but in a couple of its own files. Therefore we need to define a reader to access velocity fields in these 4D-Flow Toolbox intermediate format files. 3. Subsequently an efficient intern administration of the available medical image volumes and the associated velocity fields is crucial. We have to consider that some of the data may be of interest in different parts of the resulting software but that resources are limited on a personal computer. Furthermore most of the data is transformed to GPU-readable 3D-textures, so we have to consider an efficient way to administer data in GPU memory too. 4. The main objectives are interactive and highly efficient visualizations of interesting flow patterns with a concurrent rendering of morphological background information. The rendering of medical image volumes can be costly, so we have to consider fast algorithms for a concurrent calculation and visualization of flow patterns without a high CPU-load. Programs executed on the graphics unit of a PC seem to be ideal, so we need additional support for such kinds of algorithms. 5. To provide an overview of different flow patterns for comparison reasons we have to provide possibilities for a concurrent arrangement of different visualizations. The same data should be presented in different ways of representation. 1 PACS = Picture Archiving and Communications System 2 DICOM = Digital Imaging and Communications in Medicine 63
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Master’s Thesis Quantitative Meas
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I hereby certify that the work pres
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Kurzfassung In dieser Arbeit werden
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CONTENTS 4.2.2 Noise Suppression .
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Chapter 1 Introduction Assessment o
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Figure 1.1: This workflow diagram d
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Chapter 2 Visualization Visualizati
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2.1 Technical Visualization (a) (b)
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2.1 Technical Visualization Next a
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Chapter 6 Experiments Several atten
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6.3 Results 6.3 Results To complete
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6.4 Scalability activity. The highe
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6.4 Scalability (a) Stream lines fo
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6.4 Scalability (a) Stream tubes ap
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6.4 Scalability Figure 6.10: Compar
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Chapter 7 Future Work This chapter
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7.3 Derived Magnitudes possibilitie
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7.5 Clinical Evaluations (a) Stereo
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Beside the improvement of known spa
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Appendix A Intermediate File Format
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A.2 Data Files Offset Name Type Des
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This chapter supplements chapter 5
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143 Figure B.3: An thinned out UML
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Figure B.5: This UML class diagram
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Glossary Notation bipolar gradient
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Glossary Notation Description MIP M
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Glossary Notation Description shade
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LIST OF FIGURES 3.5 The slice-profi
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List of Tables 2.1 CPU - GPU analog
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REFERENCES [Brill1994] M. Brill, W.
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REFERENCES [iMedgine2006] T. Gross,
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REFERENCES [Kniss2002a] Joe Kniss,
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REFERENCES [Markl2003] Michael Mark
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REFERENCES [Roth1982] Scott D. Roth
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REFERENCES [Vivek1999] andAlexPang
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INDEX flow data, 135 format definit
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Master's Thesis - Studierstube Augmented Reality Project - Graz ...

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