Medicine and Health Sciences Commons^™

Automating The Radiation Therapy Treatment Planning Process For Pediatric Patients With Medulloblastoma, Soleil Hernandez

Dissertations & Theses (Open Access)

Over the past 50 years, pediatric cancer 5-year survival rates increased from 20% to 80% in high-income countries, however, these trends have not been mirrored in low-and-middle-income countries (LMICs). This is due in part to delayed diagnosis, higher rates of advanced disease at presentation and a growing lack of access to high quality medical personnel and technology necessary to deliver complex treatments.

The long-term goal of this study was to alleviate demanding workflows and increase global access to high-quality pediatric radiation therapy by harnessing the power of artificial intelligence to automate the radiation therapy treatment planning process for pediatric patients …

An Evaluation Of Methods To Reduce Inframammary Surface Dose In Prone Breast Irradiation, Seth Alvarado

Doctoral Dissertations

In cases of breast radiation treatments via external beam radiation therapy, the incidence of radiation dermatitis has been reported. In prior studies, this acute radiation side-effect has been correlated with the immobilization devices in cases of prone breast irradiation. They attribute this to the bolus effect that occurs with the interaction of the incident photon beam at different projections causing an increase in measured surface dose. The type of radiation planning technique, and patient positioning during the undertaking of these techniques, have also shown to influence this bolus effect. This study focuses on these factors in treatment planning in order …

An Evaluation Of Methods To Reduce Inframammary Surface Dose In Prone Breast Irradiation, Seth Alvarado

Culminating Experience Projects

In cases of breast radiation treatments via external beam radiation therapy, the incidence of radiation dermatitis has been reported. In prior studies, this acute radiation side-effect has been correlated with the immobilization devices in cases of prone breast irradiation. They attribute this to the bolus effect that occurs with the interaction of the incident photon beam at different projections causing an increase in measured surface dose. The type of radiation planning technique, and patient positioning during the undertaking of these techniques, have also shown to influence this bolus effect. This study focuses on these factors in treatment planning in order …

Nanoparticles For Biomedical Applications, Joseph Kim

Dissertations & Theses (Open Access)

This thesis presents development and evaluation of the potential of three new nanoparticles for biomedical applications. With the rapid growth of the field of nanoscience, researchers have explored developing nanoparticles for various biomedical applications, including imaging, therapy, and drug delivery. This thesis demonstrates the development of two C­₆₀ fullerene based nanoparticles and one boron based nanoparticle to answer key questions related to their biological potential.

In the first part of the thesis, we describe synthesis and characterization of a pure boron nanoparticle containing asolectin phospholipid-based liposome construct prepared using a water-in-oil emulsion method, as a novel alternative agent for …

Targeting Prostate Cancer Through High Dose Rate Brachytherapy, Christopher Smith

Electronic Thesis and Dissertation Repository

While prostate cancer is not typically an aggressive disease, it can be lethal for some patients. Treatment of the disease has proven to be effective; however, when the disease recurs locally it does so most commonly at the site of the dominant intraprostatic lesion (DIL). An effective treatment method for prostate cancer is high dose rate brachytherapy (HDR-BT). This is a radiation therapy where a radioactive seed is interstitially inserted into the patient to deliver the radiation dose. It was the goal of this work to utilize preprocedural imaging and pathological data from radical prostatectomy specimens to investigate methods to …

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 …

Exploring The Roles Of Long Non-Coding Rnas In Glioblastoma Tumor Recurrence And Therapy Resistance, Christian Tyler Stackhouse

All ETDs from UAB

ABSTRACT Glioblastoma (GBM) is the most common and devastating primary CNS brain tumor with a median survival time of around 14 months. Most patients succumb to re-current disease which is often more malignant than the primary tumor and is frequently therapy resistant. There have not been significant advances in the treatment of GBM despite decades of research. This is partly due to the lack of accurate preclinical models and of the focus on primary rather than recurrent tumors. We created a 350 gene custom GBM-specific panel which contains 16 molecular signatures including molecular sub-typing signatures. We have demonstrated concordance of …

Investigation Of Stereotactic Body Radiation Therapy Delivery Accuracy On An Elekta Linear Accelerator, Addie Barron

LSU Master's Theses

Purpose: This work investigated the delivery accuracy of high-dose lung and spine stereotactic treatments delivered with the Elekta Infinity and Versa HD platforms. The accuracy of these platforms will be used for consideration in implementing a spine stereotactic radiosurgery (SSRS) program at Mary Bird Perkins Cancer Center.

Methods: A geometric phantom was used to perform Winston-Lutz type tests that assessed the relevant degrees of freedom (gantry, collimator, and couch) of the delivery system. A lung stereotactic body radiation therapy (SBRT) and spine SRS treatment plan were generated for use in end-to-end testing. Delivery accuracy was tested using a novel diode …

Optimization Of Decision Making In Personalized Radiation Therapy Using Deformable Image Registration, Jason Vickress

Electronic Thesis and Dissertation Repository

Cancer has become one of the dominant diseases worldwide, especially in western countries, and radiation therapy is one of the primary treatment options for 50% of all patients diagnosed. Radiation therapy involves the radiation delivery and planning based on radiobiological models derived primarily from clinical trials. Since 2015 improvements in information technologies and data storage allowed new models to be created using the large volumes of treatment data already available and correlate the actually delivered treatment with outcomes. The goals of this thesis are to 1) construct models of patient outcomes after receiving radiation therapy using available treatment and patient …

Development Of 3d-Printed Patient Specific Bolus For Clinical Use In Total Scalp Irradiation, Garrett Baltz

Dissertations & Theses (Open Access)

Total scalp irradiation (TSI) is a specialized radiation therapy technique that aims to deliver a uniform dose to the entire scalp. Original electron-based TSI techniques had limited homogeneity due to hot and cold spots created at field junctions due to the multiple matched fields that were required to treat the entire scalp. The transition to photon volumetric-modulated arc therapy based TSI techniques has improved homogeneity, to the point where non-conformal bolus is now a limiting factor. Bolus is required to build-up full dose to the scalp surface in total scalp irradiation. Creating bolus that is conformal to the scalp is …

High-Throughput Mapping Of The Biological Effects Of Particle Therapy, Lawrence Bronk

Dissertations & Theses (Open Access)

Radiation therapy is an essential tool in the cure of many cancer patients. Charged particle based radiation therapies are gaining momentum as the physical dose distributions of ions are superior to standard photons due their limited range. Additionally, charged particle radiation has been shown to have linear energy transfer (LET) specific relative biological effectiveness (RBE) when compared to photons. It is essential to employ accurate biophysical models for particle beams in order to maximize the therapeutic potential of particle therapy through the introduction of biologically optimized treatment planning. The development of such models requires the support of large amounts of …

Investigation Of Radiation Injury In The Esophagus From Definitive Chemoradiation Therapy Using Novel Imaging Biomarkers, Joshua S. Niedzielski

Dissertations & Theses (Open Access)

Radiation injury in the esophagus occurs with high frequency from the treatment of non-small cell lung cancer (NSCLC). Radiation esophagitis is an acute normal tissue toxicity that negatively affects treatment efficacy by limiting dose and potentially interrupting radiation therapy. Clinical quantification of this toxicity is typically achieved by utilizing physician grading scales, assigning complication severity on an ordinal scale of symptom presentation and/or physician chosen interventions. These criteria are subjective in nature, both from the physician assigning the grade and the patient reporting the symptom. Furthermore, radiation therapy planning guidelines for the esophagus are derived from toxicity prediction models utilizing …

Statistical Modeling Of Interfractional Tissue Deformation And Its Application In Radiation Therapy Planning, Douglas J. Vile

Theses and Dissertations

In radiation therapy, interfraction organ motion introduces a level of geometric uncertainty into the planning process. Plans, which are typically based upon a single instance of anatomy, must be robust against daily anatomical variations. For this problem, a model of the magnitude, direction, and likelihood of deformation is useful. In this thesis, principal component analysis (PCA) is used to statistically model the 3D organ motion for 19 prostate cancer patients, each with 8-13 fractional computed tomography (CT) images. Deformable image registration and the resultant displacement vector fields (DVFs) are used to quantify the interfraction systematic and random motion. By applying …

Evaluation Of Presage® Dosimeters For Brachytherapy Sources And The 3d Dosimetry And Characterization Of The New Agx100 125i Seed Model, Olivia Huang

Dissertations & Theses (Open Access)

With continuous new improvements in brachytherapy source designs and techniques, method of 3D dosimetry for treatment dose verifications would better ensure accurate patient radiotherapy treatment. This study was aimed to first evaluate the 3D dose distributions of the low-dose rate (LDR) Amersham 6711 Oncoseed^TM using PRESAGE^® dosimeters to establish PRESAGE^® as a suitable brachytherapy dosimeter. The new AgX100 ¹²⁵I seed model (Theragenics Corporation) was then characterized using PRESAGE^® following the TG-43 protocol.

PRESAGE^® dosimeters are solid, polyurethane-based, 3D dosimeters doped with radiochromic leuco dyes that produce a linear optical density response to radiation dose. …

Improving Cervical Cancer Nodal Boost Radiation Therapy By Quantifying Uncertainties And Exploring Advanced Radiation Therapy Modalities, Zhiqian Yu

Dissertations & Theses (Open Access)

Radiation therapy for patients with intact cervical cancer is frequently delivered using primary external beam radiation therapy (EBRT) followed by two fractions of intracavitary brachytherapy (ICBT). Although the tumor is the primary radiation target, controlling microscopic disease in the lymph nodes is just as critical to patient treatment outcome. In patients where gross lymphadenopathy is discovered, an extra EBRT boost course is delivered between the two ICBT fractions. Since the nodal boost is an addendum to primary EBRT and ICBT, the prescription and delivery must be performed considering previously delivered dose. This project aims to address the major issues of …

Redox-Regulated Relb-Ar Axis Mediates Prostate Specific Antigen Expression: Insight In Prostate Cancer Response To Radiation Therapy, Lu Miao

Theses and Dissertations--Toxicology and Cancer Biology

Although the prostate specific antigen (PSA) test is widely used in clinical settings for prostate cancer (PCa) diagnosis and post-treatment follow-up monitoring, false positive PSA test results, which contribute to over-diagnosis of PCa, and false negative results, which miss some patients with aggressive PCa, remain problems of clinical importance.

Our study demonstrates that radiation therapy, which is widely used for treatment of localized PCa, generates TNF-α in tumor cells and stromal fibroblasts, redox dependently. Interestingly, TNF-α rapidly and transiently triggers the RelA-mediated NF-κB canonical pathway, but its effect on RelB expression is more robust and long lasting, which leads to …

Improving The Accuracy Of Radiation Pneumonitis Dose Response Models, Yevgeniy Vinogradskiy

Dissertations & Theses (Open Access)

The prognosis for lung cancer patients remains poor. Five year survival rates have been reported to be 15%. Studies have shown that dose escalation to the tumor can lead to better local control and subsequently better overall survival. However, dose to lung tumor is limited by normal tissue toxicity. The most prevalent thoracic toxicity is radiation pneumonitis. In order to determine a safe dose that can be delivered to the healthy lung, researchers have turned to mathematical models predicting the rate of radiation pneumonitis. However, these models rely on simple metrics based on the dose-volume histogram and are not yet …

Thoracic Radiotherapy Treatment Planning With Cine Pet/Ct, Adam C. Riegel

Dissertations & Theses (Open Access)

Purpose: Respiratory motion causes substantial uncertainty in radiotherapy treatment planning. Four-dimensional computed tomography (4D-CT) is a useful tool to image tumor motion during normal respiration. Treatment margins can be reduced by targeting the motion path of the tumor. The expense and complexity of 4D-CT, however, may be cost-prohibitive at some facilities. We developed an image processing technique to produce images from cine CT that contain significant motion information without 4D-CT. The purpose of this work was to compare cine CT and 4D-CT for the purposes of target delineation and dose calculation, and to explore the role of PET in target …