Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 26 for “"dose calculations"”.
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Improving Dose Calculations In Electron-beam Radiation Therapy
… tumour sites. However, the simplistic methods of dose calculation in current clinical use lack sufficient accuracy in many situations of clinical importance. This thesis rests on the premise that a more accurate dose calculation method must incorporate all the major physical processes which shape …
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Development and Evaluation of Advanced Dose Calculations for Modern Radiation Therapy Techniques
… fail to predict precisely the physical radiation dose distribution. Thus the clinical outcome of the treatment can not be properly evaluated by physicians. By using more sophisticated dose calculations based on superposition or Monte Carlo techniques this problem would be reduced or would actually …
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The development and use of fifteen year-old equivalent mathematical phantom for internal dose calculations
… means of obtaining estimates of absorbed dose for children of that age. Dimensions representative of an average fifteen year-old human, obtained from various biological and medical research, were transformed into a mathematical construct of idealized shapes of the exterior, skeletal …
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Voxel-Level Absorbed Dose Calculations With A Deterministic Grid-Based Boltzmann Solver For Nuclear Medicine and The Clinical Value of Voxel-Level Calculations
<p>Voxel-level absorbed dose (VLAD) is rarely calculated for nuclear medicine (NM) procedures involving unsealed sources or 90Y microspheres (YM). The current standard of practice for absorbed dose calculations in NM utilizes MIRD S-values, which 1) assume a uniform distribution in organs, 2) do …
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Development of A New Independent Monte Carlo Dose Calculation Quality Assurance Audit to ol For Clinical Trials
… (TPS) may use a number of different radiation dose calculation algorithms during the planning process. The Radiological Physics Center (RPC), tasked with ensuring clinically comparable and consistent dose delivery amongst institutions participating in NCI funded multi-institutional clinical …
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Measured dose distributions of iodine-125 sources and the computerised optimisation of their positions in brachytherapy planning
… and becoming increasingly varied. The spatial dose distributions around two types of 1-125 seeds in general use, were measured using a Geiger-Muller chamber. Seeds with the 1-125 adsorbed onto resin spheres had a 10% less anisotropic dose distribution than seeds containing a silver wire with …
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Reduction of Dose Calculation Errors For Patients With Metal Implants Receiving Photon Radiation Therapy
… these metal implants can degrade the accuracy of dose calculations. Dose calculation errors result from limitations of modern dose calculation algorithms in modeling metal/tissue interface effects. Metals also cause streak artifacts in the computed tomography (CT) images that are used for …
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Benchmarking and Implementation of A New Independent Monte Carlo Dose Calculation Quality Assurance Audit to ol For Clinical Trials
… treatment planning systems employ a variety of dose calculation algorithms to plan and predict the dose distributions a patient receives during external beam radiation therapy. Traditionally, the Radiological Physics Center has relied on measurements to assure that institutions participating in …
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Evaluation and Clinical Implementation of a Dual-Energy CT Stopping-Power Ratio Mapping Technique for Proton-Therapy Treatment Planning
… potential to treat tumors with better conformal dose distribution than competing modalities when the rapid dose falloff at the end of the proton-beam range is correctly aligned to the edge of the clinical target volume (CTV). However, its clinical potential is dependent on the accurate …
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Improving Cone-Beam Computed Tomography Based Adaptive Radiation Therapy with Deep Learning
… consequently leads to inaccuracies in CBCT-based dose calculations. Additionally, auto-segmentation of CBCT is impeded by low image quality and a lack of training labels. Although addressing this issue is difficult, enhancing auto-segmentation is essential, as manual segmentation is highly …
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ENVIRONMENTAL RADIATION DOSE ASSESSMENT AND VALIDATION FOR URANIUM HEXAFLUORIDE STORAGE MANAGEMENT
… for performing environmental radiation dose assessment for storage of a large number (thousands) of uranium hexafluoride (UF6) cylinders in an outdoor storage area. The primary objective was to substantially improve the Monte Carlo computational efficiency by an order of magnitude or …
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Dose Calculation For Electron Therapy
<p>The dose delivered by electron beams has a complex dependence on the shape of the field; any field shaping shields, design of collimator systems, and energy of the beam. This complicated dependence is due to multiple scattering of the electron beam as the beam travels from the accelerator head …
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Characterization of Oslds For Use In Small Field Photon Beam Dosimetry
… various correction factors associated with OSLD dose calculations. The uncertainties for each correction factor were also investigated. It was determined that the linearity, depletion, fading, and energy correction factors were identical to the RPC commissioning data for non-masked OSLDs. The …
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Influence on different Monte-Carlo variances at the dose calculation and the impact to the commissioning
… is gradually being introduced for clinical dose computation in the quest to improve the accuracy of predicting the dose distribution to a medium from a given beam setup. Dosimetric measurement is used to verify the accuracy of the calculated dose distribution before the beam setup can be …
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Analysis of 3D and 4D proton treatment planning for hepatic tumors
… is to assess the difference between 4D liver dose calculations versus standard 3D treatment planning and to investigate the dosimetric gain of gating on radiation dose to normal tissue. 4DCT scans are collected for 25 patients with hepatic tumors treated by proton radiotherapy. The 4D …
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Statistical analysis of renal function in patients with cancer
… rate (GFR). Many clinical decisions, for example dose calculations for chemotherapy drugs, are based on a patient’s GFR. The most accurate way to determine a patient’s GFR involves costly, time-consuming, and consequently frequently unavailable methods. Therefore, GFR is commonly estimated using …
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Applications of Voronoi partitions in particle therapy
… in modern cancer management due to its increased dose to the targeted tumors and improved sparing of surrounding normal tissues and critical structures. Many challenging and interesting mathematical optimization problems arise in the planning of charged particle radiation therapy. In this thesis, …
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Characterization of Treatment Planning System Photon Beam Modeling Errors In Iroc Houston Phantom Irradiations
… of the treatment planning system’s (TPS) dose calculation algorithm is critical because any errors in this process impact all treatment plans prepared in the system. Previously, TPS errors have been identified as a major cause for poor phantom irradiation performance, which may also mean …
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A Comparison of Two Teaching Methods for Pediatric Medication Administration: Multimedia and Text-Based Modules
… on how to calculate pound to kilogram, safe-dose ranges, intravenous flow rates, and fluid maintenance. The dependent variable was knowledge acquisition of mathematical calculation skills for medication administration. Calculation skills were defined operationally as a student's ability to …
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