Health and Medical Physics Commons^™

Establishing A Comprehensive Framework For Sfrt Lattice Treatments: Optimization, Planning, And Clinical Evaluation, Gregory M. Gill

UNLV Theses, Dissertations, Professional Papers, and Capstones

Spatially fractionated radiation therapy (SFRT) using lattice radiotherapy (LRT) has emerged as a promising treatment technique for bulky, nonresectable tumors by delivering spatially heterogeneous dose distributions consisting of high-dose vertices embedded within lower-dose regions. Although early clinical experiences have demonstrated potential therapeutic benefit, widespread clinical implementation of LRT remains limited due to the absence of standardized treatment planning workflows, consistent optimization strategies, and clearly defined evaluation metrics for heterogeneous dose distributions. The objective of this study is to develop and evaluate a structured framework to support efficient, reproducible, and safe clinical implementation of LRT.

To address these challenges, a comprehensive …

Theory, Experiments, And Image Recovery Algorithms For X-Ray Interferometry, Hunter C. Meyer

LSU Doctoral Dissertations

Purpose: X-ray grating interferometry is a form of X-ray phase contrast imaging capable of simultaneously measuring attenuation, differential-phase, and dark-field images arising from X-ray absorption, refraction, and small-angle scattering, respectively. These additional contrast mechanisms have potential clinical and industrial applications, particularly for lung tissue characterization and disease identification. As grating interferometers approach clinical viability, key challenges include reducing X-ray dose, mitigating mechanical instability, and correcting spectral artifacts resulting from beam hardening.

Methods: The modulated phase grating interferometer (MPGI) is a potential solution for reducing X-ray dose by eliminating the analyzer grating used in alternative interferometer designs, including the Talbot-Lau interferometer …

Exploring The Impact Of Adverse Childhood Experiences On Preventive Healthcare Utilization In Rural Georgia, Ryan R. Traylor

College of Graduate Studies: Theses & Dissertations

This study examines the relationship between Adverse Childhood Experiences (ACEs) and preventive healthcare use among adults in Georgia, specifically within rural populations facing structural barriers. Using 2023 Georgia Behavioral Risk Factor Surveillance System (BRFSS) data, the research analyzes associations between ACE exposure, rural residence, and preventive care outcomes, including physical exams and flu vaccinations. Guided by an intersectionally adapted version of Andersen’s Behavioral Model of Health Services Use, the study evaluates how predisposing factors, enabling resources, and perceived barriers relate to healthcare engagement. Logistic regression analyses assess the correlation of ACE exposure, cost barriers, provider access, and sociodemographics with preventive …

A Framework For Digital Energy Modulation And Translation In Projectional X-Ray Imaging, Richard R. Wargo

Theses and Dissertations

In projectional X-ray imaging, acquisition energy fundamentally influences subject contrast, image noise, and radiation dose. While dual-energy techniques exploit spectral differences to optimize contrast and enable material separation, acquiring multiple images of the same anatomy often requires additional exposures and increased system complexity.

This dissertation presents a framework for digital energy modulation (DEM), in which computational models are trained to translate projection images between energy domains without requiring additional X-ray acquisitions. DEM is conceived as a generalizable strategy for controlled contrast modulation in projection imaging, with potential applications in image optimization, radiation therapy alignment, and dual-energy applications.

The framework was …

Customized Feminine Hygiene Wash Containing Postbiotics From Lactobacillus Spp. To Treat Urinary Tract Infections (Uti), Veena G. Nair

Theses and Dissertations

Probiotics, which support host health by maintaining normal microbial flora, offer a promising approach for preventing recurrent infections. To evaluate the prophylactic potential of vaginal probiotics against urinary tract infections (UTIs), we conducted a study on 54 healthy South Indian women aged 18–40 who visited the Obstetrics and Gynaecology outpatient clinic at Trichy SRM Medical College and Research Centre between June and July 2022. Vaginal swabs were collected following ethical guidelines, and commensal microbiota were isolated for probiotic characterization, with the broader objective of developing a customized feminine hygiene wash enriched with vaginal postbiotics.

Lactobacilli cell-free supernatant (CFS) demonstrated potent …

Resilience And Reality: Exploring The Lived Experiences Of People Living With Hiv In Texas During The Covid-19 Pandemic – A Qualitative Study., Ahmed F. Alanazi

Social Work Dissertations - Archive

This study investigated the lived experiences of individuals living with HIV (PLWH) in the Dallas-Fort Worth (DFW) area of Texas during the COVID-19 pandemic, using an Interpretative Phenomenological Analysis (IPA) framework. The research examined the intersection of health, social dynamics, and psychological resilience among PLWH, who faced compounded vulnerabilities due to systemic inequities and the dual public health crises of HIV and COVID-19. Through semi-structured interviews with ten participants from diverse backgrounds, the study captured the profound impacts of disrupted healthcare systems, heightened stigma, and social isolation on this marginalized population. The findings reveal that the pandemic exacerbated existing inequities …

Post-Modeling Adjustments And Delivered Dose Verification Of The 6fff Beam Model Commissioned For The Monaco Treatment Planning System, Grant C. Debevec

LSU Master's Theses

External beam radiation therapy has been shown to be an effective treatment method for tumors and abnormalities of the spine and vertebral region. Treating the spine using a stereotactic body radiation therapy (SBRT) technique can reduce toxicity to the spinal cord. The 6 MV flattening filter free (6FFF) beam model is currently used to plan and calculate dose for SBRT treatment plans, and the treatment plans are delivered using a linear accelerator (LINAC).

The commissioned beam model represents an invariant component of a LINAC. For volumetric modulated arc therapy (VMAT) treatment plans, the multileaf collimator (MLC) positions are changing throughout …

The Theory Of X-Ray And Neutron Interferometry Using A Modulated Phase Grating, Hunter C. Meyer

LSU Master's Theses

Grating interferometry exploits wave interference to simultaneously image multiple physical properties of an object and can be performed using X-rays or neutrons. The modulated phase grating interferometer (MPGI) is a recently developed interferometry system that allows for the simultaneous acquisition of attenuation, differential-phase contrast, and dark-field images, which highlight X-ray or neutron absorption, refraction, and small angle scatter, respectively. This interferometry system uses a single grating, with a relatively high period envelope function, to produce interference fringes that can be directly resolved by standard high resolution detectors. The grating is sampled at a relatively low pitch, to meet coherence requirements …

The Role Of Sport For Adolescents: The Effect Of Sport Participation As A Unique Form Of Physical Activity On Mental Health And Overall Subjective Well-Being During Adolescence, Caleb M. Rogers

Senior Theses

Well-being is an extremely multifaceted domain, as there are numerous factors that contribute to one’s way of life. Objective well-being focuses primarily on material factors such as access to food, housing, and a steady household income. Although these factors play a large role, it is important to analyze well-being from the perspective of the individual. Subjective well-being focuses on how one perceives one's own well-being. Physical activity has been well established as one factor associated with improvements within this domain for adolescents. This project investigates the role of one specific form of physical activity during adolescence: sport. The general assumption …

Outpatient Fall Prevention In Ambulatory Adults 65 Years Old And Over, Dorothy L. Osborne-White

Doctor of Nursing Practice (DNP) Scholarly Projects - Archive

Background: In the United States (U.S.), falls are the leading cause of injury among adults 65 and over, resulting in 36 million falls yearly (Moreland et al., 2020). According to the Centers for Disease Control and Prevention (CDC, 2023), one in four older adults experiences a fall each year. Falls are the world's second most prominent cause of accidental deaths (World Health Organization [WHO], 2021). Falls are the leading cause of both fatal and non-fatal injuries among older adults (Moreland et al., 2020).

Methods: A quality improvement project that included a fall bundle was implemented in a primary clinic. A …

Patient Specific Normalized Glandular Dose Range Estimate For Mammography, Lacey Medlock

LSU Master's Theses

Breast cancer is the most common type of cancer among women in the United States. It is also the second leading cause of death by cancer among women in the United States. Early detection is key to preventing fatalities. There are over 39 million mammography screening procedures performed yearly [3]. We know that exposure to radiation, including in routine mammography, may induce secondary cancers [4]. Thus, it is important to be able to accurately estimate the dose delivered to a patient during breast cancer screening. The dose delivered to a patient is regulated in the US and in many other …

Interrogations Of The Tumor Microenvironment Using Magnetic Resonance Imaging, Tianzhe Li

Dissertations and Theses (Open Access)

Both tumor acidosis and tumor hypoxia are characteristics commonly found in the microenvironment of solid malignant tumors. Accurate characterization of the two phenomena could provide important information to clinicians for devising suitable treatment plans. Tumor acidosis and hypoxia are closely linked to each other. Tumor acidosis is caused by the inclination of cancer cells towards anaerobic respiration, and one of the main contributing factors for the avoidance of aerobic respiration is tumor hypoxia. Both phenomena can indicate the high metastatic potential of cancers and can also cause resistance of the cancer systems against anti-cancer therapies. Therefore, developing novel molecular imaging …

Ai-Enabled Online Plan Adaptation For Mr-Guided Stereotactic Ablative Radiotherapy (Sabr) Of Head And Neck Cancer, Yao Zhao

Dissertations and Theses (Open Access)

Head and neck cancer (HNC) is a prevalent cancer type worldwide. Stereotactic ablative radiotherapy (SABR) has emerged as an effective treatment for HNC, delivering highly conformal doses to the tumor target while sparing surrounding normal tissues with a sharp dose gradient. However, the accuracy of the treatment delivery is limited by setup errors, anatomical changes, and intra-/inter-fraction organ motion. The emergence of MR-guided adaptive radiotherapy (ART) has the potential to further improve the SABR of HNC, by providing superior visualization of soft tissue and enabling real-time plan adaptation based on the daily anatomical changes of patients. This novel technology has …

Treatment Planning Automation For Rectal Cancer Radiotherapy, Kai Huang

Dissertations and Theses (Open Access)

Background

Rectal cancer is a common type of cancer. There is an acute health disparity across the globe where a significant population of the world lack adequate access to radiotherapy treatments which is a part of the standard of care for rectal cancers. Safe radiotherapy treatments require specialized planning expertise and are time-consuming and labor-intensive to produce.

Purpose:

To alleviate the health disparity and promote the safe and quality use of radiotherapy in treating rectal cancers, the entire treatment planning process needs to be automated. The purpose of this project is to develop automated solutions for the treatment planning process …

Dose Calculation And Prediction Methods For Gamma Knife Stereotactic Radiosurgery, Payton Hayes Stone

LSU Doctoral Dissertations

Implementation of automation routines leveraging deep learning (DL) methods has been a growing topic of interest. The focus of this work is on the Gamma Knife (GK) workflow, specifically the approximation of dose distributions from GK plan parameters and the prediction of dose distributions using DL. These works contribute towards the larger goal of treatment plan prediction and are seen as intermediate steps towards that end. The approximation of dose distributions was motivated by the closed nature of the GK system, which causes complications with the evaluation of the predictions made by the DL models. The approximation utilizes a superposition …

Development Of A Qa Plan For A 3.0t Cannon Galan Mr-Sim, Nathaniel D. Teague

Theses and Dissertations

Purpose: To develop and incorporate a QA (quality assurance) program for a Canon Galan 3 tesla MR Simulator for applications in radiation therapy.

Methods and materials: The QA program was centered around tests performed with three separate levels of frequency. The daily QA procedure consisted of scanning a vendor provided daily QA cube phantom that measures basic performance parameters. Additionally, a series of basic safety check were performed. The monthly QA procedure consisted of several tests, including scanning the ACR MRI large accreditation phantom and manually performing its corresponding image quality tests. Scanning the MagPhan RT for its detailed geometric …

Infrastructure Development For Personalized Risk Prediction To Reduce Cardiovascular Disease In Childhood Cancer Survivors, Suman Shrestha

Dissertations and Theses (Open Access)

Although childhood cancer survivors have lengthy life expectancies, they run the risk of experiencing long-term health issues as a result of their treatment. The most frequent non-cancerous cause of morbidity and mortality for these survivors is cardiac disease. Radiation therapy (RT) has been linked in numerous cohort studies to a higher chance of developing a late cardiac disease in these survivors, and this risk rises with higher mean heart doses and increased RT exposure to larger cardiac volumes. Since, the heart is a heterogeneous organ made up of several distinct substructures, RT dose received by the entire heart does not …

A Retrospective Dosimetry Comparison To Define Uncertainties Found In A Novel Intensity Modulated Electron Therapy (Imet) Treatment Technique For Use In Radiation Therapy, Marco A. Masciantonio

Honors Undergraduate Theses

This study will investigate the difference in radiation at different volumes between traditional electron beam therapy and a novel IMET. The difference in dose will be recorded between the novel IMET and the IMET with a slight shift in the target area. The percent difference between this new model treatment and the model treatment with a shift will be calculated. The main goal of this project is to determine if the target area is still sufficiently treated with this slight shift of the patient in different directions. The percent difference is crucial for the success of this project. It will …

Investigating The Uncertainties In Ct Non-Small Cell Lung Cancer Radiomics, Gary Ge

Theses and Dissertations--Radiation Medicine

Radiomics is a technique that extracts quantitative features, termed radiomic features, from medical images using data-characterization algorithms. These radiomic features can be used to identify tissue characteristics and radiologic phenotyping that are not observable by clinicians in a non-invasive, low-cost manner, potentially generating image biomarkers for clinical decision. To date, there are still many uncertainties involved in radiomics which limit its clinical implementation. Herein, we propose to explore the impact of each component in the radiomics pipeline on predicting clinical outcomes. In Chapter II, we conduct a thorough review of CT lung cancer radiomics studies to examine the typical feature …

Modeling Of Island Block Scatter For Intensity Modulated Bolus Electron Conformal Therapy, Joseph G. Scotto

LSU Master's Theses

Purpose: Bolus electron conformal therapy (BECT) benefits treatment of the post-mastectomy chest wall, head and neck, paraspinal muscles, and extremities. Patient dose heterogeneities caused by bolus can be reduced through intensity modulation (IM) across the incident electron beam. This requires passive radiotherapy intensity modulation for electrons (PRIME) devices, which utilize tungsten pins (island blocks) imbedded in machinable foam. IM-BECT treatment planning requires accurate dose calculation using the pencil beam redefinition dose algorithm (PBRA). Currently, the PBRA models island blocks as perfect collimators. This work explores models to account for electrons scattering into and out of the sides of island blocks. …

A Deep Learning U-Net For Detecting And Segmenting Liver Tumors, Vidhya Cardozo

Theses and Dissertations

Visualization of liver tumors on simulation CT scans is challenging even with contrast-enhancement, due to the sensitivity of the contrast enhancement to the timing of the CT acquisition. Image registration to magnetic resonance imaging (MRI) can be helpful for delineation, but differences in patient position, liver shape and volume, and the lack of anatomical landmarks between the two image sets makes the task difficult. This study develops a U-Net based neural network for automated liver and tumor segmentation for purposes of radiotherapy treatment planning. Non-contrast simulation based abdominal CT axial scans of 52 patients with primary liver tumors were utilized. …

Reconsidering The Obstetrical Dilemma: Correlations Between Head And Pelvic Size, Kelsey Catrice Fox

LSU Master's Theses

The Obstetrical Dilemma (OD) theory has become canon in biological anthropology. The OD posits that i] dystocia results from bipedal mothers and encephalized infants, ii] contrasting selection for bipedality and obstetrics hinders locomotive efficiency, and iii] the contradicting requirement of the fetus being small enough to pass through the birth canal yet being cognitively advanced enough to cling to its mother after birth. Females, theoretically, exhibit deficient gait efficiency for the sake of successful childbirth. An obstetric advantage theory has been posited where taller individuals with a larger head size have larger pelves. If the distance between the acetabulae increases …

Towards Optimizing Quality Assurance Outcomes Of Knowledge-Based Radiation Therapy Treatment Plans Using Machine Learning, Phillip Douglas Hardenbergh Wall

LSU Doctoral Dissertations

Knowledge-based planning (KBP) techniques have been shown to provide improvements in plan quality, consistency, and efficiency for advanced radiation therapies such as volumetric modulated arc therapy (VMAT). While the potential clinical benefits of KBP methods are generally well known, comparatively less is understood regarding the impact of using these systems on resulting plan complexity and pre-treatment quality assurance (QA) measurements, especially for in-house KBP systems. Therefore, the overarching purpose of this work was to assess QA implications with using an in-house KBP system and explore data-driven methods for mitigating increased plan complexity and QA error rates without compromising dosimetric plan …

Quantitative Study Of The Antimicrobial Effects Of Silver On The Motility Of Escherichia Coli, Benjamin Russell

Graduate Theses and Dissertations

In recent decades, the number of antibiotic-resistant bacterial infections has grown to become a serious global threat. This rise can be attributed to the widespread misuse of antibiotics and the lack of newly developed drugs to fight resistant organisms. Novel bactericidal substances have, therefore, garnered significant research interest. Silver, due to its powerful antimicrobial effects, is one such substance. Silver is typically most effective in cationic form; however, advancements in nanotechnology have paved the way for the controlled fabrication of nano-silver. Silver nanoparticles have been shown to have increased antibacterial potency for a variety of reasons, including the release of …

Evaluating Feline Release Criteria Following Iodine-131 Therapy For Hyperthyroidism, Anthony Davila

LSU Master's Theses

Hyperthyroidism is a very common endocrine disorder in both humans and cats. Radioactive iodine ablation therapy is considered the gold standard; however, the patient becomes a radiation source and poses a potential radiological risk to others. The regulations governing when the patient can be released differ between human medicine and veterinary medicine. A human patient can receive up to 33 mCi of I-131 and be discharged the same day; yet a feline patient can receive a dose as low as 2 mCi and require multiple days of hospitalization. This discrepancy has not been satisfactorily addressed; and overly restrictive release criteria …

Stray Radiation Dose From X-Ray And Proton Beam Radiation Therapies, Christopher William Schneider

LSU Doctoral Dissertations

The growing population of cancer survivors at risk of radiation induced side-effects is a public health concern. These side-effects include serious conditions such as second cancers, the majority of which occur outside of the primary treatment volume. Radiotherapy treatment planning systems systematically underestimate the dose to tissues out-of-field. Attempts to predict and reduce the risks of radiogenic side effects require accurate and personalized knowledge of the out-of-field radiation dose to patients. The long-term goal of this research is to provide clinical and research tools necessary to reduce the risk of radiotherapy side effects and improve the health outcomes of radiotherapy …

Computational Feasibility Of Simulating Whole-Organ Vascular Networks And Their Response To Injury, William Patrick Donahue

LSU Doctoral Dissertations

Healthy vasculature is critical to sustaining the function of normal tissues in the human body. Radiation therapy for cancer causes injury of the vasculature of non-cancerous tissues. These changes have been associated with potentially deadly conditions such as necrosis of the brain tissue. There are currently no computational methods to study the effects of radiation vascular injury in whole-organ vasculatures because of the large number of vessels involved. The goal of this work was to test the feasibility of simulating radiation damage to whole-brain vascular networks and calculate the resulting change in blood flow. To accomplish this, we developed algorithms …

Determination Of Scatter Fractions, Albedos, And Tenth Value Layers For Shielding Of Synchrotron Beamline Hutches, Bethany Lynn Broekhoven

LSU Master's Theses

Synchrotron facilities require substantial amounts of shielding to protect facility staff and researchers. To meet mandatory exposure limits, the traditional combination of time, distance, and shielding of the radiation source are utilized. Because of continuous 24-7 operation of most synchrotrons, time is the least useful tool. The experimental stations for synchrotron x-ray beamlines, called hutches, enforce a minimum distance from the source, but shielding provided by hutch walls is still the principal tool for a synchrotron facility. Currently there is no single resource for synchrotron beamline hutch shielding design in the literature; most hutch shielding is designed through either over-simplified …

Framework For Algorithmically Optimizing Longitudinal Health Outcomes: Examples In Cancer Radiotherapy And Occupational Radiation Protection, Lydia Joyce Wilson

LSU Doctoral Dissertations

Background: Advancements in the treatment of non-infectious disease have enabled survival rates to steadily increase in recent decades (e.g., diabetes, heart disease, and cancer). Epidemiological studies have revealed that the treatments for these diseases can have life-threatening and/or life–altering effects. Thus, realizing the full beneficial potential of advanced treatments necessitates new tools to algorithmically consider all major components of the health outcome, including benefit and detriment. The goal of this dissertation was to develop a framework for improving projected health outcomes following planned radiation exposures in consideration of all beneficial and detrimental, early and late, and fatal and non-fatal …

Feedforward And Feedback Signals In The Olfactory System, Srimoy Chakraborty

Graduate Theses and Dissertations

The conglomeration of myriad activities in neural systems often results in prominent oscillations. The primary goal of the research presented in this thesis was to study effects of sensory stimulus on the olfactory system of rats, focusing on the olfactory bulb (OB) and the anterior piriform cortex (aPC). Extracellular electrophysiological measurements revealed distinct frequency bands of oscillations in OB and aPC. However, how these oscillatory fluctuations help the animal to process sensory input is not clearly understood. Here we show high frequency oscillations in olfactory bulb carry feedforward signals to anterior piriform cortex whereas feedback from the aPC is predominantly …