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 22 for “"ion chamber"”.
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An Evaluation of The Consistency of Imrt Patient-Specific Qa Techniques
… the integrity of an intensity modulated radiation therapy (IMRT) treatment, each plan must be validated through a measurement-based quality assurance (QA) procedure, known as patient specific IMRT QA. Many methods of measurement and analysis have evolved for this QA. There is not a standard …
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Studies of alpha-radioactivity in the marine environment
This dissertation deals with the alpha-radioactivity in the marine environment around South Africa, and the published literature relating to alpha-emitting nuclides in sea water and in marine organisms is surveyed in Chapter 1. As a first step in the investigation, the total alpha-activity of some …
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Detectors in Medical Physics Measuring Dose by Detectors
… the depth dose curve for both energies. In addition the doses were obtained by using three method of detectors suck as the ion chamber, TLDs, and films. Approximately the same results of doses were obtained for all measurement by using different detectors. Therefore, these detectors are reliable …
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The design, construction, and testing of a reactimeter
… The reactimeter is comprised of a compensated ion chamber that measures the neutron flux of the reactor and a microcomputer that performs the reactivity calculations. The calculations are based on the six group, point reactor kinetics equations. To simplify the algorithm programming into the …
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Modification and Implementation of The Rpc Heterogeneous Thorax Phantom For Verification of Proton Therapy Treatment Procedures
… phantoms that are used to evaluate radiation treatment procedures as part of a comprehensive quality assurance program for institutions participating in clinical trials. It was hypothesized that the existing RPC heterogeneous thorax phantom can be modified to assess lung tumor proton beam …
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Development and Commissioning of An Independent Peer Review System For A Small Animal Irradiator
… small animal irradiators lacks the standardization of clinical radiotherapy practice, yet plays a central translational role in human trial design. The purpose of this work was to improve the dosimetric accuracy and consistency of animal studies by developing an independent peer review system to …
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Radiobiology of normal rat lung in Boron Neutron Capture Therapy
… Capture Therapy (BNCT) is a binary cancer radiation therapy that utilizes biochemical tumor cell targeting and provides a mixed field of high and low Linear Energy Transfer (LET) radiation with differing biological effectiveness. This project investigated the radiobiology of normal rat lung in …
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Photoproduction of positive pions near threshold in hydrogen
… available measurements of pi+ photoproduction cross sections very near threshold 0 To do this, a 1410 hydrogen bubble chamber was used in an X-ray beam with Emax = 230 MeV. Meson tracks could be observed from their origins in the photon beam. Only those events were used in which the '1T+ …
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Examination of secondary electrons generated by encapsulated gamma sources to improve contact dosimetry estimates
Secondary electron generation on the surface of encapsulated gamma sources can play a large role in the dose measured near the surface of the encapsulation. The National Council on Radiation Protection and Measurements (NCRP) Report - 40 contains contact dose rate conversion factors for …
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Irradiators for measuring the biological effects of low dose-rate ionizing radiation fields
Biological response to ionizing radiation differs with radiation field. Particle type, energy spectrum, and dose-rate all affect biological response per unit dose. This thesis describes methods of spectral analysis, dosimetry, biological assays, and mathematical modeling for determining the …
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Characterizing canine dose from external beam irradiation
… basis as well as for the collective population due to increased frequency of and dependency on CT scans for diagnostic and therapeutic imaging. Colorado State University recently integrated a large bore multi-slice Positron Emission Tomography and Computed Tomography (PET/CT) scanner into …
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Development of A Remote Dosimetric Audit Framework For Carbon Therapy
<p>Carbon ion therapy is available at over a dozen institutions around the world and is being employed for treatment of cancer. The increased biological effect of carbon compared to conventional photon-based radiotherapy holds promise for the therapeutic benefit in historically radioresistant …
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In vivo imaging of cortical porosity by synchrotron phase contrast micro computed tomography
… is relatively new and allows the three dimensional quantification of change in trabecular bone microarchitecture over time. The use of in vivo µCT is limited by the radiation dose created by the x-ray beam, with commercially available in vivo systems generally operating in the 10-20 um …
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Gamma and neutron dose profiles near a Cf-252 brachytherapy source
A new generation of medical grade Cf-252 sources was developed in 2002 at the Oak Ridge National Laboratory (ORNL). The combination of small size and large activity of these Cf-252 sources makes them suitable to be used with the conventional high-dose-rate (HDR) remote afterloading systems for …
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Direct optimization of 3D dose distributions using collimator rotation
… goal of this thesis is to improve the precision and efficiency of radiation therapy treatment. This goal is achieved by developing and implementing a direct aperture optimization (DAO) platform where the multileaf collimator (MLC) is rotated between each aperture. The approach is referred to …
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Accelerator-Based Neutron Branchytherapy
The feasibility of a new modality of radiation therapy, Accelerator-Based Neutron Brachytherapy (ABNBT), has been demonstrated through simulations and experimental work. The candidate nuclear reactions investigated are 9Be(d,n)'OB, 9Be(p,n)9B, and 7Li(p,n)7Be, with charged particle beam energies of …
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Facilitating the Clinical Translation of Flash Radiotherapy Through Dosimetry Development and Beam Parameter Optimization
… Professor: Emil Schüler, PhD</p> <p>Radiation therapy (RT) is a crucial component of curative cancer therapy, with a majority of cancer patients in the United States receiving RT as part of treatment. The goal of RT is to maximize the therapeutic index in curing disease while minimizing any …
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In Vivo Dosimetry Using Plastic Scintillation Detectors For External Beam Radiation Therapy
… of dose delivered to patients during radiation therapy, has significant potential in ensuring safe and effective treatment in radiation therapy. It can serve as point-of-delivery, patient specific quality assurance and direct verification of treatment. Despite evidence that <em>in vivo</em> …
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CONE BEAM COMPUTED TOMOGRAPHY (CBCT) DOSIMETRY: MEASUREMENTS AND MONTE CARLO SIMULATIONS
… beam geometry producing a 2D image per projection. Due to its faster image acquisition time, wide coverage length per scan, and fewer motion artifacts, the CBCT system is rapidly replacing the conventional CT system and becoming popular in diagnostic and therapeutic radiology. However, there …
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