AbstractProblem MotivationBackgroundDesign SpecificationsCommon Coil DesignsExperimental DesignCoil DesignSimulationsHall Effect Probe (Gauss Meter)CalibrationSignal AmplificationData AcquisitionResultsSimulationsExperimental ResultsPotential Sources of ErrorFuture WorkConclusionsReferencesAppendix A – Product Design SpecificationsAppendix B – Simulation ScriptsBiot-Savart ComputationFieldlines ComputationUNIVERSITY OF WISCONSIN – MADISONDEPARTMENT OF BIOMEDICAL ENGINEERINGBME 200/300 – DESIGNMRI Gradient CoilsFinal ReportNeal Haas - BSACPeter Kleinschmidt – LeaderAnne Loevinger - CommunicatorLuisa Meyer - BWIG10/20/2008ContentsAbstract................ .................................................................................................................... ............. ......3Problem Motivation.....................................................................................................................................3Background..................................................................................................................................................4Design Specifications............................................................................................................................ .......6Common Coil Designs..................................................................................................................................7Experimental Design... .................................................................................................................................8Coil Design........................................................................................................................................... ....9Simulations..............................................................................................................................................9Hall Effect Probe (Gauss Meter)..................................................................................................... ........10Calibration............................................................................................................................. ............. ...10Signal Amplification................................................................................................................... ............10Data Acquisition.....................................................................................................................................11Results...................................................................................................................................... ............. .... 12Simulations................................................................................................................................. ...........12Experimental Results.............................................................................................................................13Potential Sources of Error.................................................................................................................. ....13Future Work...............................................................................................................................................14Conclusions............................................................................................................................................... . 14References................................................................................................................................................ . 16Appendix A – Product Design Specifications..............................................................................................17Appendix B – Simulation Scripts. ................................................................................................. ............. .19Biot-Savart Computation.................................................................................................................. .....19Fieldlines Computation.... ......................................................................................................................23Appendix C – Simulated and Experimental Data.................................................................... ............. ......C12AbstractAs part of a broader goal to develop novel applications of Magnetic Resonance Imaging (MRI), a low-cost and modular MRI system is currently being developed. One component of this project is the design, construction and testing of gradient coils to function within the system. Several common gradient coil designs serve as a basis for development. A simulation script was developed to approximate magnetic field strengths produced by a given coil design. In order to validate the simulation, a testing environment was developed using a Hall Probe to measure themagnetic fields created by a coil of wires. A set of coils was constructed based on a Golay pair concept with the aim of generating a linearly varying x-gradient. Though the measured data showed some variability, it corresponded fairly well to the simulated fields. The simulation showed a significant degree of linearity within a confined area of the magnetic field. The measured field also showed some linearity, though less reliably. Future work will build on the knowledge gained from the simulations and experimental data to refine data acquisition methods and to optimize coil design. Problem MotivationMagnetic Resonance Imaging (MRI) is a non-invasive medical imaging technique that creates cross-sectional images of the body. It mainly functions as a tool to help physicians diagnose medical conditions. By taking advantage of the nuclear spin inherent in protons and influencing them with a powerful magnetic field, MRIs can align the magnetic poles of all hydrogen protons (1H) in a specimen. After alignment, it creates images with the aid of radio frequency amplifiers,data acquisition units, and computers. Additionally, MRIs use gradient coils as a way to distinguish points in three-space.A clinical MRI system is not always the most convenient tool for medical use. It cannot always provide medical specialists with the detailed, potentially life-saving information that they desire.The clinical MRI at its current stage of development is not equipped to perform the needed rapid imaging. Currently the complete system is unable to image in real time. This could prove useful in many medical circumstances
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