Medicine and Health Sciences Commons^™

In-Phantom Film Measurements Of Two Treatment Planning Systems For Single-Fraction Spine Sbrt, Michael J. Taylor

LSU Master's Theses

Purpose: Treatment planning accuracy for spine stereotactic body radiation therapy (SBRT) varies depending on the dose calculation algorithm utilized in the treatment planning system (TPS). This project compared the end-to-end accuracy between spine SBRT plans calculated in a convolution-superposition based TPS (TPS_CS) and Monte Carlo based TPS (TPS_MC) with radiochromic film measurements. The hypothesis was that TPS_MC would calculate the dose gradient in the critical region between the vertebral body and the spinal cord more accurately than TPS_CS.

Methods: Single-fraction spine SBRT treatments following RTOG 0631 and local institutional guidelines were planned in …

Structural Shielding Considerations For Vmat, Ana Lucia Dieguez

LSU Master's Theses

Introduction: As noted in National Council on Radiation Protection and Measurements (NCRP) Report 151, the medical physicist or other qualified expert has the responsibility to keep abreast of any new technology or treatment method that could potentially impact structural shielding design. Volumetric arc therapy (VMAT) became prevalent after the publication of Report 151 and thus was not explicitly addressed in Report 151. If the shielding-related characteristics of VMAT differ enough from the expectations of Report 151, especially in the circumstance of a vault utilized exclusively for VMAT, a shielding design based on Report 151 could potentially be inadequate. The …

Bypassing The Blood-Brain Barrier: A Physical And Pharmacological Approach For The Treatment Of Metastatic Brain Tumors, Samuel A. Sprowls

Graduate Theses, Dissertations, and Problem Reports

This dissertation (a) provided an in depth literature review of methods to disrupt the BBB/BTB and improve therapeutic distribution to brain tumors, (b) evaluated the use of azacitidine as a single agent therapy for the treatment of brain metastasis of breast cancer and a potential molecular mechanism by which brain tropic cells are sensitized to hypomethylating agents, (c) determined the impact cannabidiol has on P-glycoprotein mediated efflux at the blood-brain barrier and its potential for use as a single agent treatment for metastatic brain tumors, (d) developed a preclinical radiation therapy protocol for use in small animals and in vitro …

Phantom Ocean, Real Impact: Natural Surf Sound Experiments Alter Foraging Activity And Habitat Use Across Taxa, Ryan N. Wardle

Master's Theses

A growing body of research focuses on how background sounds shape and alter critical elements of animals’ lives, such as foraging behavior, habitat use, and ecological interactions (Bradbury & Vehrencamp, 2011; Barber et al., 2010; Kight & Swaddle, 2011; Shannon et al., 2016). Much of this research has centered on the effects of anthropogenic noise (Dominoni et al., 2020; Francis & Barber, 2013; Ortega, 2012; Swaddle et al., 2015), but recent studies have also revealed that natural sound sources can influence animal behavior (Davidson et al., 2017; Le et al., 2019). Natural sounds, such as crashing surf, can create conditions …

Countermovement Jump Assessment For Monitoring Prolonged Fatigue In Collegiate Female Soccer Players, Jeffrey A. Wilkins

Boise State University Theses and Dissertations

Introduction: Females are 4 to 6 times more likely to sustain an anterior cruciate ligament (ACL) injury than their male counterparts during running and cutting sports, such as soccer. This sex disparity is thought to result from altered lower limb neuromuscular control that females present when fatigued at the end of practice or games. Yet, current fatigue monitoring techniques typically vary in their reliability, applicability and efficiency. Purpose: The purpose of this study is to test the feasibility of the countermovement jump (CMJ) to quickly and reliably monitor fatigue in female soccer athletes. Methods: Twenty-two (age: 19.3 ± 1.1 yrs, …

Modeling Proton Relative Biological Effectiveness Using Monte Carlo Simulations Of Microdosimetry, Mark A. Newpower

Dissertations & Theses (Open Access)

Proton therapy is a radiotherapy modality that can offer a better physical dose distribution when compared to photon radiotherapy by taking advantage of the Bragg peak, a narrow region of rapid energy loss. Proton therapy is also known to offer an enhanced relative biological effectiveness (RBE) compared to photons. In the current clinical standard, RBE is fixed at 1.1 at all points along the proton beam, meaning protons are assumed to require 10% less dose than photons to achieve target coverage and organ at risk (OAR) sparing. However, there is mounting clinical evidence, and a significant number of in vitro …

Performance Evaluation Of Material Decomposition Using Rapid Kvp-Switching Dual-Energy Ct For Assessing Bone Mineral Density, John M. Wait

Dissertations & Theses (Open Access)

Osteoporosis is diagnosed by assessing the bone mineral density (BMD) of the trabecular bone, and has previously been characterized with dual-energy x-ray absorptiometry (DXA) or single-energy computed tomography (SECT). Dual-energy computed tomography (DECT) is able to create two three-dimensional sets of images representing the densities of two materials in a given basis pair. DECT is theoretically capable of providing a true density measurement of trabecular bone material with the proper material basis pair.

Using the rapid kVp-switching GE HD750 scanner, the concentrations of various solutes were assessed in two-material syringe-phantoms in different experimental conditions with DECT material density images, SECT …

Forecasting Longitudinal Changes In Oropharyngeal Tumor Volume, Position, And Morphology During Image-Guided Radiation Therapy, Adam D. Yock

Dissertations & Theses (Open Access)

The purpose of this work was to generate, evaluate, and compare models that predict longitudinal changes in oropharyngeal tumor volume, position, and morphology during radiation therapy.

One volume, one position, and two morphology (size, shape, and position) feature vectors were used to describe 35 oropharyngeal gross tumor volumes (GTVs) during radiation therapy. The two morphology feature vectors comprised the coordinates of the GTV centroids and one of two shape descriptors. One shape descriptor was based on radial distances between the GTV centroid and 614 surface landmarks. The other was based on a spherical harmonic decomposition of these distances. For a …

Impact Testing Of Youth-Level Helmets Versus College-Level Helmets, Nicole Hermann

Industrial Technology and Packaging

With so many studies being conducted on professional football players regarding concussions and other related brain injuries, it’s amazing that such an important demographic has been missed. While NFL players are just as subjected to serious injuries as anyone else or even more so, it is important to remember that these players are outfitted, in most cases, with top-of-the-line equipment -- especially their helmets. If the focus is shifted to a younger demographic, youth football players in middle school and high school, the equipment is far less advanced and in a vast majority of cases, has been previously used by …

Modeling Thermal Inactivation Of Bacillus Spores, Emily A. Knight

Theses and Dissertations

This research models and analyzes methods to damage Bacillus anthracis spores through heat treatment. AFIT researchers have developed methods to characterize the effects of heating spores to high temperatures and for short durations similar to the thermal pulse of conventional weapon detonation. This research models the current experiment and evaluates the rate of thermal diffusion throughout the spores. A micro-model of the effects of dry and wet heating on a spore is presented. Heating a spore energizes adsorbed, absorbed, and chemically bound water molecules. These energized molecules have greater mobility within the spore, as well as between the spore and …

Exercise Adherence: Motivational Factors Influencing Exercise Adherence And Fitness Level, Justin Recklau

Undergraduate Theses and Capstone Projects

There are many factors that influence adherence to an exercise program. This research study aimed to determine which factors most effectively ensured adherence, with the hypothesis that no single factor was indicative of exercise adherence as adherence is a dynamic item. The results target exercise professionals to assist them in retaining clientele and encouraging clientele to adhere to exercise programs. A survey was implemented that had clients self-report their stage in the transtheoretical model as well as how strongly they felt about five positive factors to exercise as well as five barriers to exercise. In addition to surveys, body composition, …

Downstream Pathway Activation In Cultured Hepatocytes Following Treatment With Francisella Tularensis, Nicole Wakefield

Undergraduate Theses and Capstone Projects

Francisella tularensis, the intracellular pathogen that causes tularemia, was investigated to determine how it infects and replicates within mammalian hepatocytes. To date, it has been shown that hepatocytes can be infected by F. tularensis and that this causes considerable change in the protein phosphorylation state of several vital signaling molecules within the host cell. Protein kinase pathways can be mapped as signatures of infection. Hepatocytes tend to be susceptible to infection by F. tularensis, thus stimulating internal signaling. The Francisella strains used were selected with the goal of producing a model that can be used to elucidate the cell signaling …

The Effects Of A Low-Intensity Exercise Program On The Fitness Level Of A 22 Year-Old Female With Congenital Univentricular Heart Repair, Alice A. Elkins

Theses, Dissertations and Capstones

This case study examined the effects of exercise on a 22 year-old female with a repaired univentricular heart through early, modified Fontan technique. Improvements in oxygen consumption, blood pressure, heart rate and body composition were observed after a 12-week supervised fitness program. This program considers reversing hypoactivity and the subsequent deconditioning and obesity associated with this patient.

The Coronary Distribution Zone : Mathematical Modelling Of The Left Ventricular Epicardial Surface For Area Calculation, Three-Dimensional Rotaton And Display, S. Matts E. Sjölander

Loma Linda University Electronic Theses, Dissertations & Projects

A computer model of the left ventricular (LV) epicardial surface was developed from Jang’s truncated ellipsoidal model, which has a minor to major axis ratio of 6:10. The model was applied in calculating the area of a segment of the myocardium, jeopardized by an impending occlusion of its associated artery. The endangered segment of the LV muscle was also visualized in different projections by rotations in three space and graphical displays simulating the three dimensions.

The area formula for the surface of the ideal model , a truncated prolate spheroid, was derived and used in producing maps for manual calculations …