Ai-Driven Segmentation And Volumetric Response Modeling Of Liver Regions To Radiotherapy, Aashish Chandra Gupta

Dissertations and Theses (Open Access)

In liver-directed radiotherapy (RT), liver regions receiving higher doses typically undergo atrophy while contralateral/adjacent lower-dose regions may exhibit compensatory hypertrophy through regeneration of healthy tissue. Optimizing the RT plan to promote regional hypertrophy while minimizing the risk of developing atrophy has the potential to enhance post-RT liver function and long-term survivorship. However, current clinical practice largely relies on global liver dose-volume metrics during RT-planning, which may obscure favorable dose-response correlation and limit actionable guidance for clinicians. Therefore, we hypothesized that post-RT regional liver response is governed by a combination of region-specific dose-volume and patient clinical features, and that these responses …

Development Of Lineal Energy Spectrum-Based Biological Effects Models For Protons, Joseph M. Decunha, Fada Guan, David Grosshans, Zhongxing Liao, Dragan Mirkovic, Oleg Vassiliev, Radhe Mohan

Dissertations and Theses (Open Access)

In this dissertation, methods are developed and described to allow for the rapid calculation of microdosimetric spectra (specifically, lineal energy) for protons. SuperTrack, a GPU-accelerated tool for calculation of microdosimetric spectra was developed and is capable of computing lineal energy spectra up to 5000x faster than using Geant4 directly. Proton lineal energy spectra generated by SuperTrack are indistinguishable from those generated by Geant4. With SuperTrack, large libraries of lineal energy spectra for monoenergetic protons spanning 0-300 MeV have been developed. The proton lineal energy spectra calculated by SuperTrack have been compared to experimental measurements made by a tissue equivalent proportional …

Automated To Ols For Contour Review In Radiotherapy, Barbara Marquez

Dissertations and Theses (Open Access)

Peer review of organ-at-risk and target volume delineation is essential for patient safety and optimization of treatment outcomes. Peer review makes a substantial impact on patient outcomes, reporting notable rates of plan changes when reviewed and worse survival when patient cases are not reviewed. In around half of revised cases, target volume change is the required cause for modification (related to tumor control); in one in ten cases, it is normal tissue sparing (related to treatment toxicity). Essentially all North American institutions with accredited residency training programs hold peer review to some capacity. However, accessibility to practicing routine peer review …

Influential Factors And Predicting Dose Delivery Accuracy For Imaging And Radiation Oncology Core’S Phantom Program Using Machine Learning, Hunter Mehrens

Dissertations and Theses (Open Access)

IROC’s mission is to help ensure consistent and comparable, high-quality radiotherapy across clinics that participate in national clinical trials. To obtain this mission, IROC’s phantom program provides a third-party end-to-end check of the clinical workflow of a patient receiving radiotherapy. The goal of the phantom audit is to compare the dose delivered to the dose planned by the treatment system ensuring dose delivery accuracy. While IROC’s phantoms are better equipped to catch dose delivery errors compared to a clinic’s QA process, the end-to-end process and reporting of results is time-consuming creating a bottleneck for clinical trial participation. Furthermore, IROC’s passing …

Identification Of Immune-Associated Biomarkers Of Diabetes Nephropathy Tubulointerstitial Injury Based On Machine Learning: A Bioinformatics Multi-Chip Integrated Analysis, Lin Wang, Jiaming Su, Zhongjie Liu, Shaowei Ding, Yaotan Li, Baoluo Hou, Yuxin Hu, Zhaoxi Dong, Jingyi Tang, Hongfang Liu, Weijing Liu

Faculty, Staff and Student Publications

BACKGROUND: Diabetic nephropathy (DN) is a major microvascular complication of diabetes and has become the leading cause of end-stage renal disease worldwide. A considerable number of DN patients have experienced irreversible end-stage renal disease progression due to the inability to diagnose the disease early. Therefore, reliable biomarkers that are helpful for early diagnosis and treatment are identified. The migration of immune cells to the kidney is considered to be a key step in the progression of DN-related vascular injury. Therefore, finding markers in this process may be more helpful for the early diagnosis and progression prediction of DN.

METHODS: The …

Evaluation Of An End-To-End Radiotherapy Treatment Planning Pipeline For Prostate Cancer, Mohammad Daniel El Basha, Court Laurence, Carlos Eduardo Cardenas, Julianne Pollard-Larkin, Steven Frank, David T. Fuentes, Falk Poenisch, Zhiqian H. Yu

Dissertations and Theses (Open Access)

Radiation treatment planning is a crucial and time-intensive process in radiation therapy. This planning involves carefully designing a treatment regimen tailored to a patient’s specific condition, including the type, location, and size of the tumor with reference to surrounding healthy tissues. For prostate cancer, this tumor may be either local, locally advanced with extracapsular involvement, or extend into the pelvic lymph node chain. Automating essential parts of this process would allow for the rapid development of effective treatment plans and better plan optimization to enhance tumor control for better outcomes.

The first objective of this work, to automate the treatment …

Methods For The Prediction Of Osteoradionecrosis Resulting From Head And Neck Cancer Radiation Therapy, Brandon Reber

Dissertations and Theses (Open Access)

Head and neck cancer (HNC) is the sixth most diagnosed cancer worldwide with over 600,000 patients diagnosed every year. One of the primary methods to treat HNC is through radiation therapy (RT). While RT is effective at treating HNC, late toxicities resulting from treatment can occur months to years post-treatment and can cause debilitating quality of life changes for HNC survivors. One of these late toxicities is osteoradionecrosis (ORN), which is the death of bone due to radiation. For HNC, the mandible is commonly affected and can cause challenges chewing, swallowing, and physical appearance changes. Several factors indicate the pressing …

Inter-Individual Variations In Circadian Misalignment-Induced Nafld Pathophysiology In Mice, Nobuya Koike, Yasuhiro Umemura, Hitoshi Inokawa, Isao Tokuda, Yoshiki Tsuchiya, Yuh Sasawaki, Atsushi Umemura, Naoko Masuzawa, Kazuya Yabumoto, Takashi Seya, Akira Sugimoto, Seung-Hee Yoo, Zheng Chen, Kazuhiro Yagita

Faculty, Staff and Student Publications

Pathological consequences of circadian misalignment, such as shift work, show considerable individual differences, but the lack of mechanistic understanding hinders precision prevention to prevent and mitigate disease symptoms. Here, we employed an integrative approach involving physiological, transcriptional, and histological phenotypes to examine inter-individual differences in pre-symptomatic pathological progression, preceding irreversible disease onset, in wild-type mice exposed to chronic jet-lag (CJL). We observed that CJL markedly increased the prevalence of hepatic steatosis with pronounced inter-individual differences. Stratification of individual mice based on CJL-induced hepatic transcriptomic signature, validated by histopathological analysis, pinpoints dysregulation of lipid metabolism. Moreover, the period and power of …

The Development Of Artificial Intelligence-Based To Ols For Expert Peer Review Of Radiotherapy Treatment Plans, Mary Gronberg

Dissertations and Theses (Open Access)

Creating a patient-specific radiation treatment plan is a time-consuming and operator-dependent manual process. The treatment planner adjusts the planning parameters in a trial-and-error fashion in an effort to balance the competing clinical objectives of tumor coverage and normal tissue sparing. Often, a plan is selected because it meets basic organ at risk dose thresholds for severe toxicity; however, it is evident that a plan with a decreased risk of normal tissue complication probability could be achieved. This discrepancy between “acceptable” and “best possible” plan is magnified if either the physician or treatment planner lacks focal expertise in the disease site. …

Machine Learning For Ecg Diagnosis And Risk Stratification Of Occlusion Myocardial Infarction, Salah S Al-Zaiti, Christian Martin-Gill, Jessica K Zègre-Hemsey, Zeineb Bouzid, Ziad Faramand, Mohammad O Alrawashdeh, Richard E Gregg, Stephanie Helman, Nathan T Riek, Karina Kraevsky-Phillips, Gilles Clermont, Murat Akcakaya, Susan M Sereika, Peter Van Dam, Stephen W Smith, Yochai Birnbaum, Samir Saba, Ervin Sejdic, Clifton W Callaway

Faculty, Staff and Students Publications

Patients with occlusion myocardial infarction (OMI) and no ST-elevation on presenting electrocardiogram (ECG) are increasing in numbers. These patients have a poor prognosis and would benefit from immediate reperfusion therapy, but, currently, there are no accurate tools to identify them during initial triage. Here we report, to our knowledge, the first observational cohort study to develop machine learning models for the ECG diagnosis of OMI. Using 7,313 consecutive patients from multiple clinical sites, we derived and externally validated an intelligent model that outperformed practicing clinicians and other widely used commercial interpretation systems, substantially boosting both precision and sensitivity. Our derived …

The Role Of Native Cysteine Residues In The Oligomerization Of Kcnq1 Channels, Alison Bates, Rebecca B Stowe, Elizabeth M Travis, Lauryn E Cook, Carole Dabney-Smith, Gary A Lorigan

Faculty, Staff and Student Publications

KCNQ1, the major component of the slow-delayed rectifier potassium channel, is responsible for repolarization of cardiac action potential. Mutations in this channel can lead to a variety of diseases, most notably long QT syndrome. It is currently unknown how many of these mutations change channel function and structure on a molecular level. Since tetramerization is key to proper function and structure of the channel, it is likely that mutations modify the stability of KCNQ1 oligomers. Presently, the C-terminal domain of KCNQ1 has been noted as the driving force for oligomer formation. However, truncated versions of this protein lacking the C-terminal …

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

Dissertations and 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 …

Mechanosensitive Membrane Proteins: Usual And Unusual Suspects In Mediating Mechanotransduction, Miriam B Goodman, Elizabeth S Haswell, Valeria Vásquez

Faculty, Staff and Student Publications

This Viewpoint, which accompanies a Special Issue focusing on membrane mechanosensors, discusses unifying and unique features of both established and emerging mechanosensitive (MS) membrane proteins, their distribution across protein families and phyla, and current and future challenges in the study of these important proteins and their partners. MS membrane proteins are essential for tissue development, cellular motion, osmotic homeostasis, and sensing external and self-generated mechanical cues like those responsible for touch and proprioception. Though researchers' attention and this Viewpoint focus on a few famous ion channels that are considered the usual suspects as MS mechanosensors, we also discuss some of …

Structural Insights Into Cardiolipin Replacement By Phosphatidylglycerol In A Cardiolipin-Lacking Yeast Respiratory Supercomplex, Elena G Govorunova, Oleg A Sineshchekov, Leonid S Brown, Ana-Nicoleta Bondar, John L Spudich

Faculty, Staff and Student Publications

Potassium-selective channelrhodopsins (KCRs) are light-gated K+ channels recently found in the stramenopile protist Hyphochytrium catenoides. When expressed in neurons, KCRs enable high-precision optical inhibition of spiking (optogenetic silencing). KCRs are capable of discriminating K+ from Na+ without the conventional K+ selectivity filter found in classical K+ channels. The genome of H. catenoides also encodes a third paralog that is more permeable for Na+ than for K+. To identify structural motifs responsible for the unusual K+ selectivity of KCRs, we systematically analyzed a series of chimeras and mutants of this protein. We found that mutations of three critical residues in the …

Quantifying The Magnitude Of To Tal Dose Deviation Caused By Various Sources Of Error Among Iroc Phantom Irradiation Results, Sharbacha S. Edward

Dissertations and Theses (Open Access)

The Imaging and Radiation Oncology Core (IROC) phantoms are used as an end-to-end test of an institution’s radiotherapy processes, and for clinical trial credentialing. Phantoms are treated like patients, and evaluation of the doses received by the thermoluminescent dosimeters (TLDs) inside the phantom, reflects the accuracy with which an institution can image, plan and irradiate a phantom or patient. Recent phantom results show that among the hundreds of various IROC phantoms irradiated annually, 8-17% of institutions fail this test. The purpose of this work was to investigate the various types of errors that may occur during the treatment process and …

Absolute Quantification Of Tc-99m Activity Distributions Using A Planar Molecular Breast Imaging Commercial System, Benjamin P. Lopez

Dissertations and Theses (Open Access)

Molecular breast imaging (MBI) uses two dedicated-breast semiconductor detectors to visualize the preferential uptake of technetium-99m-sestamibi (^99mTc-sestamibi) by breast cancer cells relative to surrounding benign breast tissues. Clinically, MBI is used primarily as a supplementary tool to standard-of-care mammography because of its improved detection of breast cancers, especially in women with mammographically-dense breasts. Because of a lack of image corrections, MBI applications are currently limited to qualitative evaluations of relative pixel intensities between image regions with suspected lesions and normal tissue.

The objective of this dissertation was to use Monte Carlo simulations to better characterize the MBI imaging …

Development Of Advanced Mr-Guided Adaptive Radiation Therapy Methods For Head & Neck Cancers On The 1.5t Mr-Linac, Brigid Mcdonald

Dissertations and Theses (Open Access)

The 1.5T hybrid MRI/linear accelerator (MR-linac) has recently been introduced into clinical practice and used for the treatment of head and neck cancers (HNC). This device enables on-line adaptive radiation therapy (ART) based on anatomical changes throughout treatment and variations in patient position. This novel technology also has the potential for advanced ART strategies such as dose-optimized ART, in which the treatment plan is optimized based on the accumulated dose over previous fractions, or biological image-guided ART, in which the plan is adapted based on individual tumor response as measured through quantitative imaging techniques such as diffusion-weighted imaging (DWI). The …

Biophysical Characterization Of Light-Gated Ion Channels Using Planar Automated Patch Clamp, Elena G Govorunova, Oleg A Sineshchekov, Leonid S Brown, John L Spudich

Faculty, Staff and Student Publications

Channelrhodopsins (ChRs) are proteins that guide phototaxis in protists and exhibit light-gated channel conductance when their genes are heterologously expressed in mammalian cells. ChRs are widely used as molecular tools to control neurons and cardiomyocytes with light (optogenetics). Cation- and anion-selective ChRs (CCRs and ACRs, respectively) enable stimulation and inhibition of neuronal activity by depolarization and hyperpolarization of the membrane, respectively. More than 400 natural ChR variants have been identified so far, and high-throughput polynucleotide sequencing projects add many more each year. However, electrophysiological characterization of new ChRs lags behind because it is mostly done by time-consuming manual patch clamp …

Development Of Quantitative Molecular Photoacoustic Imaging For Noninvasive Cancer Diagnostics, Cayla Zandbergen

Dissertations and Theses (Open Access)

Traditional diagnostic imaging provides clinicians with anatomical information that guides both diagnosis and treatment planning; however, once a tumor has progressed enough to be visible, it has often reached an advanced stage. Molecular imaging techniques allow for real-time visualization of chemical and biological processes via imaging of specific biomarkers, which can facilitate detection of malignancies before they become visible. One biomarker of interest is blood oxygen saturation (SO₂) due to its correlation with hypoxia, which is associated with increased tumor malignancy; some studies have also established SO₂ as an independent biomarker of disease progression. Additionally, because cancerous …

Advancement Of A 3d Computational Phantom And Its Age Scaling Methodologies For Retrospective Dose Reconstruction Studies, Aashish Gupta

Dissertations and Theses (Open Access)

We have used a 3D age-scalable computational phantom for over two decades for retrospective dose reconstruction studies of childhood cancer survivors (CCS) treated with 2D historic radiotherapy (RT). However, our phantom and its age scaling functions (ASF) must be updated so that it can be used in studies that include survivors treated with contemporary RT. We aimed to implement our phantom and its age scaling functions in DICOM format and determine the feasibility of applying our ASFs to accurately scale the whole-body CT-based anatomies.

In the implementation study, we developed Python scripts that model the phantom and ASFs in a …

Hyperpolarized Carbon-13 Magnetic Resonance Measurements Of Tissue Perfusion And Metabolism, Keith Michel

Dissertations and Theses (Open Access)

Hyperpolarized Magnetic Resonance Imaging (HP MRI) is an emerging modality that enables non-invasive interrogation of cells and tissues with unprecedented biochemical detail. This technology provides rapid imaging measurements of the activity of a small quantity of molecules with a strongly polarized nuclear magnetic moment. This polarization is created in a polarizer separate from the imaging magnet, and decays continuously towards a non-detectable thermal equilibrium once the imaging agent is removed from the polarizer and administered by intravenous injection. Specialized imaging strategies are therefore needed to extract as much information as possible from the HP signal during its limited lifetime.

In …

Investigating The Metabolic Progression Of Glioblastoma With Hyperpolarized Magnetic Resonance, Travis Salzillo

Dissertations and Theses (Open Access)

Rapid diagnosis and therapeutic monitoring of aggressive diseases such as glioblastoma (GBM) can improve patient survival by providing physicians the time to optimally deliver treatment. This includes early in development, while the tumor is still manageable, or following initial therapy, when alternative treatments should be considered. The main goal of this project was to determine whether metabolic imaging with hyperpolarized magnetic resonance spectroscopy (MRS) could detect changes in tumor progression more rapidly than conventional anatomic magnetic resonance imaging (MRI) in patient-derived GBM murine models. To comprehensively capture the dynamic nature of cancer metabolism, in vivo pyruvate-to-lactate conversion with hyperpolarized MRI, …

Development Of Fully Balanced Ssfp And Computer Vision Applications For Mri-Assisted Radiosurgery (Mars), Jeremiah Sanders

Dissertations and Theses (Open Access)

Prostate cancer is the second most common cancer in men and the second-leading cause of cancer death in men. Brachytherapy is a highly effective treatment option for prostate cancer, and is the most cost-effective initial treatment among all other therapeutic options for low to intermediate risk patients of prostate cancer. In low-dose-rate (LDR) brachytherapy, verifying the location of the radioactive seeds within the prostate and in relation to critical normal structures after seed implantation is essential to ensuring positive treatment outcomes.

One current gap in knowledge is how to simultaneously image the prostate, surrounding anatomy, and radioactive seeds within the …

Development And Implementation Of A Homogeneous And A Heterogeneous Anthropomorphic End To End Quality Assurance Audit System Phantom For Magnetic Resonance Guided Radiotherapy Modalities Ranging From 0.35 T To 1.50 T, Angela Steinmann

Dissertations and Theses (Open Access)

Introduction: Magnetic resonance (MR) guided radiation therapy (MRgRT) is an emerging field that integrates an MR imager with either a linear accelerator or three radioactive cobalt-60 sources. Before institutions participate in multi-institutional NCI-sponsored clinical trials, they are required to perform a credentialing test provided by IROC-Houston. During the credentialing test, end-to-end phantoms are used to evaluate the institution’s ability to perform consistent and accurate radiation treatments. IROC-Houston’s conventional anthropomorphic phantoms are not visible in MR, thus they are insufficient for MRgRT systems. The purpose of this work was to create an anthropomorphic thorax and a head and neck (H&N) phantom …

Equipment To Address Infrastructure And Human Resource Challenges For Radiotherapy In Low-Resource Settings, Rachel Mccarroll

Dissertations and Theses (Open Access)

Millions of people in low- and middle- income countries (LMICs) are without access to radiation therapy and as rate of population growth in these regions increase and lifestyle factors which are indicative of cancer increase; the cancer burden will only rise. There are a multitude of reasons for lack of access but two themes among them are the lack of access to affordable and reliable teletherapy units and insufficient properly trained staff to deliver high quality care. The purpose of this work was to investigate to two proposed efforts to improve access to radiotherapy in low-resource areas; an upright radiotherapy …

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

Dissertations and 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 …

Identifying The Immune Related Metabolic Properties Of Pancreatic Cancer Using Nuclear Magnetic Resonance Spectroscopy And Dynamic Magnetic Resonance Spectroscopic Imaging With Hyperpolarized Pyruvate, Joseph Weygand

Dissertations and Theses (Open Access)

Despite its relatively low incidence, pancreatic cancer was the fourth leading cause of cancer-related death in the US in 2015. This is due in part to pancreatic cancer’s natural resistance to both chemotherapy and radiotherapy. Immunotherapy presents an attractive potential treatment approach, but initial trials in mice have proved ineffective. Because cancer cells exhibit a significant increase in metabolic activity relative to normal tissue, an understanding of the metabolic function of tumors in systems with different levels of immunocompetence is a critical first step to develop an understanding of the immune-related metabolic properties of the tumor, which have potential application …

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

Dissertations and 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 …

Volumetric, Magnetic Resonance-Visible, And Radiation-Sensitive Detectors For Magnetic Resonance Image-Guided Radiation Therapy, Hannah J. Lee

Dissertations and Theses (Open Access)

VOLUMETRIC, MAGNETIC RESONANCE-VISIBLE, AND RADIATION-SENSITIVE DETECTORS FOR MAGNETIC RESONANCE IMAGE-GUIDED RADIATION THERAPY

Hannah Jungeun Lee

Advisory Professor: Geoffrey S. Ibbott, Ph.D.

Due to the superior soft-tissue contrast of magnetic resonance imaging (MRI) compared to conventional computed tomography (CT) and other on-board imaging techniques, several groups have integrated MRI and radiation treatment machine systems. The advent of MR image-guided radiation therapy (MR-IGRT) using systems, such as the 1.5 MRI – 7 MV linear accelerator (MR-Linac), now allow for improved soft-tissue on-board imaging for patient position and tumor target localization verification and the ability to assess functional biological tissue characteristics with MRI, …

Development And Implementation Of An Anthropomorphic Head & Neck Phantom For The Assessment Of Proton Therapy Treatment Procedures, Daniela Branco

Dissertations and Theses (Open Access)

Proton therapy has been used to treat cancer for more than 50 years, and over the past decade, its use has grown rapidly. One of the main goals of modern radiation therapy is to deliver a high dose to the planning target volume (PTV) with minimal exposure and damage to the surrounding healthy tissue. Protons offer a unique advantage over photon radiotherapy in that they deposit dose over a finite range, in contrast to the more gradual energy deposition of photon and electron beams. At present, 23 proton centers are in operation in the United States and another 13 centers …