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Articles 1 - 6 of 6
Full-Text Articles in Medicine and Health Sciences
A Quantitative Method For Reproducible Ionization Chamber Alignment To A Water Surface For External Beam Radiation Therapy Depth Dose Measurements, James Ververs
Theses and Dissertations
Ionization chambers (ICs) are the most commonly used detectors for radiation therapy dose measurements. Typical IC measurements use cylindrical ICs in a water phantom and therefore require initial IC alignment to the water surface. This alignment has long been ignored and only recently has a qualitative governing recommendation been made. This thesis describes a reproducible methodology for quantitative ionization chamber water surface alignment. Depth-ionization measurements are taken with twenty-eight IC designs under varying conditions including, but not limited to, changes in scan direction, speed, and resolution, radiation beam type, field size, energy, and electron contamination. Measurements are acquired using standard …
Statistical Image Reconstruction For Quantitative Computed Tomography, Joshua Evans
Statistical Image Reconstruction For Quantitative Computed Tomography, Joshua Evans
Theses and Dissertations
Statistical iterative reconstruction (SIR) algorithms for x-ray computed tomography (CT) have the potential to reconstruct images with less noise and systematic error than the conventional filtered backprojection (FBP) algorithm. More accurate reconstruction algorithms are important for reducing imaging dose and for a wide range of quantitative CT applications. The work presented herein investigates some potential advantages of one such statistically motivated algorithm called Alternating Minimization (AM). A simulation study is used to compare the tradeoff between noise and resolution in images reconstructed with the AM and FBP algorithms. The AM algorithm is employed with an edge-preserving penalty function, which is …
Contextual Factors And Reproductive Control In U.S. Women, Brianna Magnusson
Contextual Factors And Reproductive Control In U.S. Women, Brianna Magnusson
Theses and Dissertations
Introduction: Access to family planning services is a major public health issue. State policies and funding for family planning services may increase access to contraceptive services and help women avoid unintended pregnancies. Study Design: We identified sexually active, fertile women participants of the National Survey of Family Growth (2006-2008). Women were categorized as consistent or inconsistent users of contraceptives based on self-report. States were classified based on 2006 Medicaid family planning waiver status (income expansions, limited expansions, or no Medicaid family planning expansions), 2006 public funding for family planning in dollars per woman, and insurance coverage of contraceptive mandate status …
Radiation Therapy Treatment Plan Optimization Accounting For Random And Systematic Patient Setup Uncertainties, Joseph Moore
Radiation Therapy Treatment Plan Optimization Accounting For Random And Systematic Patient Setup Uncertainties, Joseph Moore
Theses and Dissertations
External-beam radiotherapy is one of the primary methods for treating cancer. Typically a radiotherapy treatment course consists of radiation delivered to the patient in multiple daily treatment fractions over 6-8 weeks. Each fraction requires the patient to be aligned with the image acquired before the treatment course used in treatment planning. Unfortunately, patient alignment is not perfect and results in residual errors in patient setup. The standard technique for dealing with errors in patient setup is to expand the volume of the target by some margin to ensure the target receives the planned dose in the presence of setup errors. …
Characterization Of A Blast Wave Device And Blast Wave Induced Traumatic Brain Injury In A Rat Model By Magnetic Resonance Imaging And Spectroscopy, Frank Corwin
Theses and Dissertations
Blast wave induced traumatic brain injury (bTBI) is a modality of injury that has come into prominence at the current time due to the large number of military and civilian personnel who have experienced the localized shock wave produced by explosive devices. The shock wave will travel concentrically outward from the explosive center, being absorbed and transmitted thru soft objects, such as tissue, and reflecting off stationary obstructions. Transmission and absorption in tissues can result in a number of physiological measureable injuries, the most common of which being what is frequently called “blast lung”. Blast lung involves the spalling effect …
The Epidemiology Of Human Rabies Postexposure Prophylaxis In Virginia, 2002 And 2003, Marilyn Goss Haskell
The Epidemiology Of Human Rabies Postexposure Prophylaxis In Virginia, 2002 And 2003, Marilyn Goss Haskell
Theses and Dissertations
Objective: To describe a sample that received human rabies postexposure prophylaxis (PEP) in Virginia as a result of animal exposures in 2002 and 2003 and to determine the extent to which PEP decisions were appropriate.Methods: PEP surveillance data were requested from 35 Virginia health districts within 5 regions. Retrospective chart review was used to gather demographic, exposure and source animal data from patient records and animal exposure reports. Descriptive statistics are presented. True exposures and appropriateness of PEP were defined using the 2004 Virginia Rabies Control Guidelines and the Recommendations of the 1999 Advisory Committee on Immunization Practices. The 2003 …