A technology gap persists in the visualization of optically inaccessible flow fields such as those in integrated systems. Advances in positron emission tomography (PET) technology are enabling its use in the engineering field to address this technology gap. This dissertation discusses a numerical study performed to characterize a modern PET system’s ability to reconstruct a three-dimensional mapping of the optically inaccessible flow field downstream of an orifice. A method was devised to simulate a ring detector response to a fluorine-18 radioisotope/water solution injected into the flow through a standard thickness pipe with orifice. A commercial computational fluid dynamics code and the Geant4 Applications for Tomographic Emission Monte-Carlo simulation physics package were used to carry out the simulations. Results indicate that geometrical features, such as the pipe internal diameter, can be resolved to within a few millimeters with specific activity levels of 155 Bq/Voxel (91.2 Bq/mm3), and acquisition times as low as 15 seconds. Results also suggest that flow features, such as the radial extent of the shear layer between the primary and secondary, recirculating flow can be resolved to within 5 mm with the same activity level, but with acquisition times of 45 seconds. Additionally, a series of simulations were performed to establish a count rate performance curve for the unique subject of the present study. A resulting peak noise equivalent count rate (NECR) of 37 kcps (counts per second) was obtained at a total activity level of 13 MBq within the detector field of view. The identified peak NECR and acquisition times, combined with reported maximum producible quantities of F-18 radioisotope were used to determine if the PET flow visualization technique was feasible. Resulting maximum allowable acquisition durations of 858.5 s and 1450.5 s were clear indications of the feasibility of this techniques ability to visualize the flow features of interest.
|Advisor:||Gross, Andreas, Pate, Stephen|
|Commitee:||Papavassiliou, Vassilios, Shu, Fangjun, Brown, Susan|
|School:||New Mexico State University|
|Department:||Mechanical and Aerospace Engineering|
|School Location:||United States -- New Mexico|
|Source:||DAI-B 82/7(E), Dissertation Abstracts International|
|Subjects:||Aerospace engineering, Physics|
|Keywords:||Computational fluid dynamics, Monte Carlo simulation, Optically inaccessible flow visualization, Pipe flow, Positron emission tomography|
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