Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains ix, 65 p. : ill. Vita. Includes abstract. Includes bibliographical references (p. 54-57).

The increasing demand for efficient cancer treatment inspired the researchers for new investigations about an alternative treatment of cancer. Microwave ablation is the newest ablation technique to cure cancer. This method is minimally noninvasive and inexpensive compared to the other methods. However, current microwave ablation systems suffer due to narrowband nature of the antenna (dipole or slot) placed at the tip of the probe. Therefore, this study developed an ultra-wideband ablation probe that operates from 300MHz to 10 GHz. For this purpose, a small wideband antenna is designed to place at the tip of the probe and fabricated. These probes are tested at ISM frequencies (2.4 GHz and 5.8GHz) in skin mimicking gels and pig liver. Microwave ablation probe design, simulation results, and experiment results are provided in this thesis.

Os aplicadores de 90Sr+90Y utilizados no Brasil em betaterapia para prevenção de quelóide e pterígio são importados e suas características dosimétricas são obtidas através de tabelas e manuais dos fabricantes apenas de forma ilustrativa pelos fabricantes. A rotina exaustiva dos profissionais de física médica nos serviços de radioterapia muitas vezes não viabiliza a realização de procedimentos para confirmação destes parâmetros. Este trabalho apresenta o desenvolvimento de uma metodologia para dosimetria de aplicadores de betaterapia de 90Sr+90Y. O software MCNP5 que é baseado no método de Monte Carlo foi utilizado para simulação das curvas de porcentagem de dose profunda e perfis de distribuição de dose produzidos por estes aplicadores. As medidas experimentais da atenuação da radiação, perfil radial e axial, foram realizadas com uma mini-câmara de extrapolação, dosímetros termoluminescentes e filmes radiocrômicos. Os resultados das medidas experimentais foram comparados com os valores simulados. Ambas as curvas de porcentagem de dose profunda e os perfis de distribuição de dose radiais, teóricos e experimentais, apresentaram boa concordância, o que pode validar o uso do software MCNP5 para estas simulações, reforçando a viabilidade do uso deste método nos procedimentos de dosimetria destas fontes emissoras de radiação beta. / The 90Sr+90Y applicators, used in Brazil betatherapy for prevention of keloids and pterigium, are imported and their dosimetric features are obtained through charts and manuals provided only in an illustrated form by the manufacturers. The exhaustive routine of the medical physicists in the clinic often do not make possible the accomplishment of procedures for the confirmation of these parameters. This work presents the development of a methodology for the dosimetry of 90Sr+90Y betatherapy applicators. The MCNP5 software that is based on the Monte Carlo method was used for the simulation of the percentage depth dose curves and dose distribution profiles produced by these applicators. The experimental measurements of the radial and axial radiation attenuation, have been done with a mini-extrapolation chamber, thermoluminescent dosimeters and radiographic films. The experimental results have been compared with the simulated values. Both percentage depth dose curves and the radial dose profiles, the theoretical and the experimental ones, have presented good agreement, which may validate the use of the MCNP5 software for these simulations, confirming the viability of the usage of this method in procedures of beta emitter sources dosimetry.

Os aplicadores de 90Sr+90Y utilizados no Brasil em betaterapia para prevenção de quelóide e pterígio são importados e suas características dosimétricas são obtidas através de tabelas e manuais dos fabricantes apenas de forma ilustrativa pelos fabricantes. A rotina exaustiva dos profissionais de física médica nos serviços de radioterapia muitas vezes não viabiliza a realização de procedimentos para confirmação destes parâmetros. Este trabalho apresenta o desenvolvimento de uma metodologia para dosimetria de aplicadores de betaterapia de 90Sr+90Y. O software MCNP5 que é baseado no método de Monte Carlo foi utilizado para simulação das curvas de porcentagem de dose profunda e perfis de distribuição de dose produzidos por estes aplicadores. As medidas experimentais da atenuação da radiação, perfil radial e axial, foram realizadas com uma mini-câmara de extrapolação, dosímetros termoluminescentes e filmes radiocrômicos. Os resultados das medidas experimentais foram comparados com os valores simulados. Ambas as curvas de porcentagem de dose profunda e os perfis de distribuição de dose radiais, teóricos e experimentais, apresentaram boa concordância, o que pode validar o uso do software MCNP5 para estas simulações, reforçando a viabilidade do uso deste método nos procedimentos de dosimetria destas fontes emissoras de radiação beta. / The 90Sr+90Y applicators, used in Brazil betatherapy for prevention of keloids and pterigium, are imported and their dosimetric features are obtained through charts and manuals provided only in an illustrated form by the manufacturers. The exhaustive routine of the medical physicists in the clinic often do not make possible the accomplishment of procedures for the confirmation of these parameters. This work presents the development of a methodology for the dosimetry of 90Sr+90Y betatherapy applicators. The MCNP5 software that is based on the Monte Carlo method was used for the simulation of the percentage depth dose curves and dose distribution profiles produced by these applicators. The experimental measurements of the radial and axial radiation attenuation, have been done with a mini-extrapolation chamber, thermoluminescent dosimeters and radiographic films. The experimental results have been compared with the simulated values. Both percentage depth dose curves and the radial dose profiles, the theoretical and the experimental ones, have presented good agreement, which may validate the use of the MCNP5 software for these simulations, confirming the viability of the usage of this method in procedures of beta emitter sources dosimetry.

The acute nervous system toxicity of organophosphate (OP) pesticides is well described. However, the reported long-term effects of OP pesticides on the nervous system are inconsistent. This inconsistency may be due to imprecise estimates of pesticide exposure, variability of central nervous system (CNS) and peripheral nervous system (PNS) assessment, small samples, and poor control of confounding. The primary goal of this research was to examine the association between long-term OP pesticide use on CNS and PNS function among pesticide applicators. An additional goal was to examine the association between high pesticide exposure events (HPEEs), which typically do not result in acute toxicity, and CNS function. Study participants were recruited from among applicators enrolled in the Agricultural Health Study (AHS) in Iowa and North Carolina. In 2006-2008, 701 male pesticide applicators completed a battery of neurobehavioral (NB) and neurological tests. Information about individual pesticide use was obtained from previous AHS interviews and a questionnaire administered during NB testing. Associations between pesticide use and neurological outcomes were estimated with linear and logistic regression models while controlling for covariates. When associations were examined between agent-specific pesticide use and nine NB tests, significantly poorer performance was observed on four tests and significantly better performance on five tests. Additionally, for some pesticides, we observed differential associations by state, suggesting that regional differences in pesticide practices may influence neurotoxicity. Overall, our results did not provide strong evidence that OP pesticide use was associated with adverse NB test performance. A history of at least one HPEE was reported by 23 percent of participants. Significant adverse associations were observed between HPEEs and two of the nine NB tests. Participants with HPEEs were, on average, 4.9 seconds slower on a test of visual scanning/processing, and 2.2 seconds slower on a test of visual scanning/motor speed. Overall, small but meaningful associations were observed between HPEEs and adverse CNS function. When associations were examined between pesticide use and PNS function, five of six neurological physical examination outcomes were associated with ever-use of one or more OP pesticides. Odds ratios ranged from 1.9 to 3.1. However, mostly null associations were observed between OP pesticide use and electrophysiological tests, hand strength, sway speed and vibrotactile threshold. This study provides some evidence that long-term exposure to OP pesticides is associated with impaired PNS function. In summary, our results suggest that exposure to a few individual OP pesticides as well as HPEEs may contribute to adverse neurological function. The observed exposure-effect associations were present after adjustment for confounding and were independent of past-diagnosed pesticide poisoning. We believe this research contributes important new evidence to an inconsistent literature. Reducing pesticide exposure and preventing HPEEs among pesticide applicators remain important public health goals.

The popularity of variable-rate technology (VRT) has grown. However, the limitations and errors ofthis technology are generally unknown. Therefore, a spatial data model was developed to generate "asapplied"surfaces to advance precision agricultural (PA) practices. A test methodology based on ASAEStandard S341.2 was developed to perform uniform-rate (UR) and variable-rate (VR) tests to characterizedistribution patterns testing four VRT granular applicators (two spinner spreaders and two pneumaticapplicators). Single-pass UR patterns exhibited consistent shapes for three of the applicators with patternsshifts observed for the fourth applicator. Simulated overlap analysis showed that three of the applicatorsperformed satisfactorily with most CVs less than 20% while one applicator performed poorly (CVs andgt;25%). The spinner spreaders over-applied at the margins but the pneumatic applicators under-appliedsuggesting a required adjustment to the effective swath spacing. Therefore, it is recommended that CVsaccompany overlap pattern plots to ensure proper calibration of VRT application.Quantification of the rate response characteristics for the various applicators illustrated varying delayand transition times. Only one applicator demonstrated consistent delay and transition times. A sigmoidalfunction was used to model the rate response for applicators. One applicator exhibited a linear responseduring a decreasing rate change. Rate changes were quicker for the two newer VR control systemssignifying advancement in hydraulic control valve technology. This research illustrates the need forstandard testing protocols for VRT systems to help guide VRT software developers, equipmentmanufacturers, and users.The spatial data model uses GIS functionality to merge applicator descriptive patterns with a spatialfield application file (FAF) to generate an 'as-applied' surface representing the actual distribution ofgranular fertilizer. Field data was collected and used to validate the "as-applied" spatial model.Comparisons between the actual and predicted application rates for several fields were madedemonstrating good correlations for one applicator (several R2 andgt; 0.70), moderate success for anotherapplicator (0.60 andlt; R2 andlt; 0.66), and poor relationships for the third applicator (R2 andlt; 0.49). A comparison ofthe actual application rates to the prescription maps generated R2 values between 0.16 and 0.81demonstrating inconsistent VRT applicator performance. Thus, "as-applied" surfaces provide a means toproperly evaluate VRT while enhancing researchers' ability to compare VR management approaches.

Typescript. / Thesis (D.P.H.)--University of Hawaii at Manoa, 1990. / Includes bibliographical references (leaves 215-222). / Microfiche. / xiv, 222 leaves, bound ill., 2 col. maps 29 cm

Thesis (Ph.D. (Tropical Medicine))--Mahidol University, 2007. / LICL has E-Thesis 0025 ; please contact computer services. LIRV has E-Thesis 0025 ; please contact circulation services.