Nuclear Science and Engineering Institute electronic theses and dissertations (MU)The electronic theses and dissertations of the Nuclear Science and Engineering Institute.https://hdl.handle.net/10355/52642024-03-29T15:54:54Z2024-03-29T15:54:54Z3D imaging for brachytherapy patient and mold applicator positioning verificationPokhrel, Sagarhttps://hdl.handle.net/10355/667402022-09-27T19:36:07Z2017-01-01T00:00:00Z3D imaging for brachytherapy patient and mold applicator positioning verification
Pokhrel, Sagar
We developed a stereo vision method for 3D imaging of HDR brachytherapy skin cancer applicator positioning and tracking with respect to patients' anatomical features. The setup consists of two high-resolution scientific scan cameras (3840 x 2748 pixels) mounted on high-precision 4D of freedom optical mounts for submillimeter and sub degree positioning. A Rando phantom was used as a surrogate for patients' skin cancer and keloid treatments using a 3D printed applicator. Stereo images were recorded and analyzed using an in-house developed LabVIEW interface to determine the relative position of the applicator with respect to skin reference markers. Oncentra treatment planning system was used to perform reference applicator positioning in X, Y and Z coordinate to evaluate the stereo system accuracy and resolution. Calibration of the system spatial resolution shows optimal performance at 1000mm from the camera imaging plane to the imaged object. Calibrated screen target measurements show that positional error in the XY-plane is less than 0.39[plus or minus]0.21mm and a discrepancy in depth measurement within 0.48[plus or minus]0.32mm. Rando phantom experiments were performed to mimic skin cancer facial treatments. Tracking several reference points at the applicator we validate an average localization precision of 0.41[plus or minus]0.32mm, 0.46[plus or minus]0.38mm, and 0.3[plus or minus]0.21mm for the X, Y, and Z coordinates respectively. Applicator misplacement was simulated to determine dosimetric errors originated by applicator positioning inaccuracies. Misalignment of applicator by 5mm caused dosimetric shift up to 2.6% for overall PTV and 6.45% in reference points in treated region. The developed 3D imaging system was validated as a high-resolution and accurate stereo vision solution capable of submillimeter pre-treatment, intra and inter-fraction applicator positioning, and repeatability. This system can be used to continuously track the intra-fraction motion of the skin applicator with respect to the patient's anatomical surface to enhance treatment accuracy, safety, and quality.
2017-01-01T00:00:00ZThe adsorption of fission products on VHTR structural materialsBranney, Sean J., 1980-https://hdl.handle.net/10355/120012022-09-27T18:41:06Z2010-01-01T00:00:00ZThe adsorption of fission products on VHTR structural materials
Branney, Sean J., 1980-
The Very High Temperature Reactor (VHTR) is being considered as a candidate for the next generation of nuclear reactors. There are several areas that require further study in VHTR reactor designs. One such area is the adsorption of fission products on the reactor's structural materials, such as graphite and stainless steel. It is important to know how much of these fission products have adsorbed on various parts of the reactor both for the purposes of understanding the possible activity of the components during maintenance operations, and also to quantify potential releases of these fission products during accident scenarios. The adsorption of fission products on reactor materials has been studied in the past, but further data are required. This project was undertaken in order to acquire some of these data. Several analysis methods were used during the course of this study, including Gravimetry, Neutron Activation Analysis, Energy Dispersive Spectroscopy, and Inductively Coupled Plasma Mass Spectroscopy. Some isotherm data has been generated and recommendations for future work have been formulated.
The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract, appears in the public.pdf file.; Title from PDF of title page (University of Missouri--Columbia, viewed on October 25, 2011).; Thesis advisor: Dr. Tushar Ghosh.; Vita.; Ph. D. University of Missouri--Columbia 2010.
2010-01-01T00:00:00ZAdsorption of water vapor by selected containment aerosols : chlorides and cement dustLi, Zhiping, 1967-https://hdl.handle.net/10355/58552022-09-27T19:07:23Z2006-01-01T00:00:00ZAdsorption of water vapor by selected containment aerosols : chlorides and cement dust
Li, Zhiping, 1967-
[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] The macroscopic adsorption isotherms of water vapor on selected containment aerosols of a nuclear reactor such as cesium iodide, cesium chloride, potassium chloride, lithium chloride, and containment concrete dust were studied using a Cahn 2000 electrobalance. The equilibrium adsorption data were obtained at various relative humidities and temperatures. The adsorption isotherm data of water vapor on cesium chloride, potassium chloride, and cesium iodide are of Type III. The adsorption isotherm data of water vapor on containment concrete are Type VIII. The equilibrium adsorption data on all these adsorbents provided a single characteristic curve when correlated according to Polanyi's potential theory. Hysteresis was observed upon desorption for cesium chloride and containment concrete samples. The isosteric heats of adsorption were calculated at different loadings. The isosteric heats of adsorption illustrate that all the adsorbents provided energetically heterogeneous adsorption sites. Jovanovic equation and an empirical equation suggested by Loyalka and Ghosh were used to fit the data over the entire pressure range.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file.; Title from title screen of research.pdf file (viewed on May 6, 2009); Vita.; Thesis (Ph. D.) University of Missouri-Columbia 2006.
2006-01-01T00:00:00ZAerosol evolution : explorations in DSMC and sectional techniquesCampbell, Shawn A.https://hdl.handle.net/10355/490582022-09-27T19:35:50Z2015-01-01T00:00:00ZAerosol evolution : explorations in DSMC and sectional techniques
Campbell, Shawn A.
Understanding and improved modeling of aerosol evolution in nuclear reactor accidents is important in estimations of the nuclear source term as it is greatly affected by the formation and presence of aerosols in the reactor primary vessel and containment. Current numerical methods such as the widely used sectional technique used by MAEROS in MELCOR and CONTAIN have major inherent approximations which undermine their accuracy and versatility. In this work, the nature of some of the sectional approximations was explored for both single and multi-component aerosols as well as their influence on results. Efforts were then made towards improving the fidelity of the sectional technique to the particle physics by coupling it with a Direct Simulation Monte Carlo (DSMC) method. In addition to this, an alternative, mesh-free method for modeling a non-homogeneous aerosol with DSMC is presented which utilizes a clustering technique. The Partioning Around Medoids (PAM) technique associates particles according to a distance parameter and can be used in place of a mesh for associating neighboring particles for interaction. This cluster method and its application to DSMC are detailed and benchmarked.
2015-01-01T00:00:00Z