Engineering Commons^™

Design & Delivery Of Automated Winston-Lutz Test For Isocentric & Off-Axis Delivery Stability Utilizing Truebeam Developer Mode & Electronic Portal Imaging Device, Mahmoud Mohammad Yaqoub

UNLV Theses, Dissertations, Professional Papers, and Capstones

The uncertainties in treatment delivery cannot be ignored in radiation therapy. Thus, the quality assurance QA tests are very important task of the medical physicist in clinical practice. Assuring the coincidence between the mechanical isocenter of the Linear Accelerator (LINAC) and its radiation beams isocenter is one of the most important qualities need to be tested, and the Winston Lust (WL) test is the

most popular technique to perform this task, especially for the treatment modalities which need high precision in beam delivery such as the stereotactic radiosurgery/stereotactic body radiotherapy (SRS/SBRT). The linear accelerator-based SRS/SBRT is a well-established method in …

Photoacoustic Elastography And Next-Generation Photoacoustic Tomography Techniques Towards Clinical Translation, Pengfei Hai

McKelvey School of Engineering Graduate Student Theses & Dissertations

Ultrasonically probing optical absorption, photoacoustic tomography (PAT) combines rich optical contrast with high ultrasonic resolution at depths beyond the optical diffusion limit. With consistent optical absorption contrast at different scales and highly scalable spatial resolution and penetration depth, PAT holds great promise as an important tool for both fundamental research and clinical application. Despite tremendous progress, PAT still encounters certain limitations that prevent it from becoming readily adopted in the clinical settings. This dissertation aims to advance both the technical development and application of PAT towards its clinical translation.

The first part of this dissertation describes the development of photoacoustic …

Developing Wavefront Shaping Techniques For Focusing Through Highly Dynamic Scattering Media, Ashton Hemphill

McKelvey School of Engineering Graduate Student Theses & Dissertations

One of the prime limiting factors of optical imaging in biological applications is the diffusion of light by tissue, which prevents focusing at depths greater than the optical diffusion limit of ~1 mm in soft tissue. This greatly restricts the utility of optical diagnostic and therapeutic techniques, such as optogenetics, microsurgery, optical tweezing, and phototherapy of deep tissue, which require focused light in order to function. Wavefront shaping extends the depth at which optical focusing may be achieved by compensating for phase distortions induced by scattering, allowing for focusing through constructive interference.

However, due to physiological motion, scattering of light …

Fluorescence Guided Tumor Imaging: Foundations For Translational Applications, Jessica P. Miller

McKelvey School of Engineering Graduate Student Theses & Dissertations

Optical imaging for medical applications is a growing field, and it has the potential to improve medical outcomes through its increased sensitivity and specificity, lower cost, and small instrumentation footprint as compared to other imaging modalities. The method holds great promise, ranging from direct clinical use as a diagnostic or therapeutic tool, to pre-clinical applications for increased understanding of pathology. Additionally, optical imaging uses non-ionizing radiation which is safe for patients, so it can be used for repeated imaging procedures to monitor therapy, guide treatment, and provide real-time feedback. The versatile features of fluorescence-based optical imaging make it suited for …

Functional Electrical Stimulation Of Peripheral Nerve Tissue Via Regenerative Sieve Microelectrodes, Matthew Reagan Macewan

McKelvey School of Engineering Graduate Student Theses & Dissertations

Functional electrical stimulation (FES) of peripheral nervous tissue offers a promising method for restoring motor function in patients suffering from complex neurological injuries. However, existing microelectrodes designed to stimulate peripheral nerve are unable to provide the type of stable, selective interface required to achieve near-physiologic control of peripheral motor axons and distal musculature. Regenerative sieve electrodes offer a unique alternative to such devices, achieving a highly stable, selective electrical interface with independent groups of regenerated nerve fibers integrated into the electrode. Yet, the capability of sieve electrodes to functionally recruit regenerated motor axons for the purpose of muscle activation remains …

Transcriptional Regulation Of Arrhythmia: From Mouse To Human, Yun Qiao

McKelvey School of Engineering Graduate Student Theses & Dissertations

In the last two decades, our understanding of cardiac arrhythmias has been accelerated immensely by the development of genetically engineered animals. Transgenic and knockout mice have been the “gold standard” platforms for delineating disease mechanisms. Much of our understanding of the pathogenesis of atrial and ventricular arrhythmias is gained from mouse models that alter the expression of specific ion channels or other proteins. However, cardiac arrhythmias such as atrial fibrillation are heterogeneous diseases with numerous distinct conditions that could not be explained exclusively by the disruption of ionic currents. Increasing evidence suggests disruption of signaling pathways in the pathogenesis of …

Developing Photoacoustic Tomography Devices For Translational Medicine And Basic Science Research, Tsz Wai Wong

McKelvey School of Engineering Graduate Student Theses & Dissertations

Photoacoustic (PA) tomography (PAT) provides volumetric images of biological tissue with scalable spatial resolutions and imaging depths, while preserving the same imaging contrast—optical absorption. Taking the advantage of its 100% sensitivity to optical absorption, PAT has been widely applied in structural, functional, and molecular imaging, with both endogenous and exogenous contrasts, at superior depths than pure optical methods. Intuitively, hemoglobin has been the most commonly studied biomolecule in PAT due to its strong absorption in the visible wavelength regime.

One of the main focuses of this dissertation is to investigate an underexplored wavelength regime—ultraviolet (UV), which allows us to image …

Poly- L -Lactic Acid- Co-Poly(Pentadecalactone) Electrospun Fibers Result In Greater Neurite Outgrowth Of Chick Dorsal Root Ganglia In Vitro Compared To Poly- L -Lactic Acid Fibers, Alexis M. Ziemba, Keith P. Lane, Ignacio M. San Segundo, Anthony R. D'Amato, Andrew K. Mason, Ryan J. Sexton, Hubert Casajus, Richard A. Gross, David T. Corr, Ryan J. Gilbert

Chemical and Biochemical Engineering Faculty Research & Creative Works

Electro spun poly-l-lactic acid (PLLA) fiber scaffolds are used to direct axonal extension in neural engineering models. We aimed to improve the efficacy of these fibers in promoting neurite outgrowth by altering surface topography and reducing fiber elastic modulus through the incorporation of a compatibilized blend, poly-l-lactic acid-poly(pentadecalactone) (PLLA-PPDL) into the solution prior to electrospinning. PLLA+PLLA-PPDL fibers had a larger diameter, increased surface nano topography, and lower glass transition temperature than PLLA fibers but had similar mechanical properties. Increases in neurite outgrowth on PLLA+PLLA-PPDL fibers were observed, potentially due to the significantly increased diameter and surface coverage with nano topography. …

Thermal Fluid Models Of A Hydrogel Delivery System For Pancreatic Cancer Treatment, Nesrine Bouhrira

Theses and Dissertations

Pancreatic cancer is one of the most devastating cancers with low survival rates. This disease is difficult to detect due to the pancreas's location deep within the body. Therefore, diagnoses are often made in the later stages, making treatment options more limited and difficult. It has been hypothesized that direct injection into the tumor would enhance drug effectivenes. Therefore, we examined the use of endoscopic ultrasound (EUS) combined with a fine needle injection to deliver a drug-eluding thermosensitive hydrogel directly into the tumor. Unfortunately normal body temperatures surrounding the EUS can warm the hydrogel drug combination beyond its phase transition …

Assessment Of Risk In Preterm Infants Using Point Process And Machine Learning Approaches, Venkata Naga Sai Apurupa Amperayani

Electrical Engineering Theses

Preemies, infants who are born too soon, have a higher incidence of Life-Threatening Events (LTE’s) such as apnea (cessation of breathing), bradycardia (slowing of heart rate) and hypoxemia (oxygen desaturation) also termed as ABD (Apnea, Bradycardia, and Desaturation) events. Clinicians at Neonatal Intensive Care Units (NICU) are facing the demanding task of assessing the risk of infants based on their physiological signals. The aim of this thesis is to develop a risk stratification algorithm using a machine-learning framework with the features related to pathological fluctuations derived from point process model that will be embedded into the current physiological recording system …

A Study Of Acoustically Activated Nanodroplets, Songita Choudhury

Theses & Dissertations

Current treatment of acute myocardial infarction (AMI), which is the main pathophysiological event leading to death in the United States, has advanced considerably with the introduction of emergent percutaneous interventions, but there remains an urgent need for novel techniques to rapidly and accurately detect infarcted or ischemic tissue that results from AMI. Ultrasound contrast agents, also known as microbubbles (MB), have become commonplace in echocardiography. However, MBs are purely intravascular tracers and unable to cross endothelial barriers due to size. The limitations of MBs, namely size and short circulation times within the human body, led to the development of phase-change …

Determinants Of Multi-Scale Patterning In Growth Plate Cartilage, Alek Erickson

Theses & Dissertations

ABSTRACT

Functional architectures of complex adaptive systems emerge by dynamic control over properties of individual components. During skeletal development, growth plate cartilage matches bone geometries to body plan requisites by spatiotemporally regulating chondrocyte actions. Bone growth potential is managed by the proximodistal patterning of chondrocyte populations into differentiation zones, while growth vectors are specified by the unique columnar arrangement of clonal groups. Chondrocyte organization at both tissue and cell levels is influenced by a cartilage-wide communication network that relies on zone-specific release and interpretation of paracrine signals. Despite genetic characterization of signaling interactions necessary for cartilage maturation, the regulatory mechanisms …

Design Of A Homeopathic Solution For Chronic Cough, Jacob Ziemke

Senior Honors Projects, 2010-2019

Chronic cough is most commonly defined as a cough that persists for more than eight weeks and is estimated to affect more than 30 million people in the United States at any given time. Diseases contributing to the onset of chronic cough include asthma, pulmonary fibrosis, lung cancer, postnasal drip, gastroesophageal reflux disease (GERD), and bronchitis, and may include lifestyle choices such as smoking. For those who seek medical advice, pharmaceuticals and speech therapy are two common methods of combating chronic cough but serve to mask the symptoms rather than treat the problem; frequently, chronic cough is misdiagnosed or cannot …

Verification And Validation Of Forces From Hippotherapy Rein Simulator, Sonia Sanchez

Graduate Theses - Biology & Biomedical Engineering

The thesis describes the redevelopment, testing, and validation of a rein training device intended to help riders learn to guide a horse during hippotherapy sessions. The thesis aims to validate and verify that the forces read by the redeveloped rein simulator were operant within ± 150 grams of the actual weight applied, as well as to investigate the effect of temperature on the system. The simulator focuses on the use of the English style of riding that uses direct force from the reins to guide a horse to turn or stop. Data was collected by hanging weights from the load …

Modeling Eeg And Tdcs In Scirun Software Packages, Aiden Keene, Aiden Thomas Keene

Senior Honors Projects

Never before has there been a greater emphasis on improving the shortcomings of treating mental health conditions. Our generation has more knowledge about technological practices with the potential to monitor and treat mental health symptoms than that of any generation before us. A breakthrough in this field made by CREmedical is called Tripolar Concentric Ring Electrodes (TCRE’s), which can measure signals from the brain more accurately than conventional electrodes. At CREmedical, TCREs are being used to study differences in electrical activity in the brain so as to identify abnormalities, and monitor responses to stimulation therapies. This semester I had the …

Effect Of Silk-Based Hydrogel Topography On Intestinal Epithelial Cell Morphology And Wound Healing In Vitro, Marisa E. Boch

University Scholar Projects

Recent advances in the field of biomaterials have suggested that cells cultured on substrates resembling the native tissue mechanical properties, matrix and growth factor composition, and topography can adopt phenotypes that more closely resemble the in vivo tissue compared to cells cultured on non-mimetic constructs. Understanding the effect of culture substrate on in vitro tissue formation is important for bioengineering applications that include mechanistic studies of healthy tissue function and development of disease models. In this work, Caco-2 adenocarcinoma cells were seeded on flat and crypt-like topographies of 3D-printed cytocompatible hydrogels derived from silk fibroin protein. Silk hydrogels were selected …

3d Printed Force Transducers For In-Vitro Mitral Valve Chordae Tendineae Force Measurements, Hayley Chandler

Biomedical Engineering Undergraduate Honors Theses

Mitral valve surgery is incredibly prevalent in the United States with more than 40,000 mitral valve surgical procedures annually. Improving the imaging techniques used to diagnose these cases requires validation of 3D models through experimental data such as mechanical properties of the tissue. An essential part of this process for the mitral valve is measuring the force experienced by chordae tendineae. This has been achieved with brass force transducers but using a 3D printed design can have many benefits. In this study, 3D printed miniature c-shaped force transducers comparable to previous metal models were designed and created using Solidworks 2016. …

Investigation Of Functional Connectivity And Neurovascular Coupling In Different Vigilance / Breath-Hold States Of The Brain From Simultaneous Eeg-Fnirs Measurements, Olajide Babawale

Bioengineering Dissertations - Archive

Functional connectivity and neurovascular coupling are important phenomena that occur in the brain. Functional connectivity is the study of functional brain networks and their characteristics. While neurovascular coupling is the relationship or link between neuronal activity and corresponding cerebral blood flow in the brain. Up until now, both functional connectivity and neurovascular coupling have not been studied in different vigilance states of the brain from wakeful rest state to sleep state, using simultaneous EEG-fNIRS measurements. Also, the neurovascular coupling in different states of breath-holding has not been studied using simultaneous EEG-fNIRS measurements Therefore, my doctoral research utilized a whole-head simultaneous …

Creep Response And Adhesion Dynamics Of Glioblastoma Multiforme Cells During Migration In Confined Environment, Ishan Kamal Khan

Bioengineering Dissertations - Archive

Glioblastoma multiforme (GBM) is the most common and malignant form of primary brain tumor. One of the major challenges facing the treatment of GBM tumors is the detachment and subsequent migration of peripheral cells. Migration of GBM cells take place in mechanically distinct confined microenvironment along the borders of white matter tracts. Studies using microfluidic devices mimicking the in-vivo microenvironment have shown that the migration characteristics are significantly altered with the change in kinematic state of the migrating cell. Several studies on different types of cells have consistently shown that a cancerous cell is more compliant than a normal cell …

Investigation Of 1064-Nm Laser Fluence Within Tissue Phantoms And Its In Vivo Effects On Human Brain Networks, Hasan Parvez

Bioengineering Theses - Archive

For the past few decades there has been an increasing interest in the usage of near infrared (NIR) laser in the medical optics field. This is due to a number of studies conducted on different animal models utilizing NIR laser, which was reported to provide improvement in such cognitive functions as memory, decision making, and executive functions. The NIR laser produces no adverse effects in the human tissue, having a potential for treating different neurological disorders. However, there is limited knowledge related to the underlying mechanism of photon interaction with the human tissue. In this thesis, I tried to address …

Quantification Of Tumor-Associated Macrophages Following Immunomodulation Therapy In A Murine Allograft Model Of Colorectal Carcinoma, Caroline Spainhour

Biomedical Engineering Undergraduate Honors Theses

Colorectal Carcinoma (CRC) is one of the deadliest cancers in the world, with 150,000 new cases annually in the United States. Traditional treatments include chemotherapy and invasive surgery; however, research has shown that only 25% of patients that undergo traditional treatment have a positive result. Immunotherapy is an emerging form of cancer treatment that utilizes the patients’immune system to fight cancer cells by targeting inflammation, which plays a large role in the proliferation and metastasis of cancer cells.

Tumor-associated macrophages (TAMs) are immune cells that affect the inflammatory microenvironment of tumors. TAMs are M1 in the early stages of tumors, …

Role Of Local Renin-Angiotensin System In Altering Valve Interstitial Cell Phenotype, Sophia Scalise

Biomedical Engineering Undergraduate Honors Theses

Hypertension is a disorder prevalent in adults around the world and is a common attributable cause of heart disease and mortality [1]. Calcification is much more common in the aortic valve than the other three heart valves [2]. Aortic valve interstitial cells (VICs), the principal cell type found in the human aortic valve, have been linked to disease development when they change in phenotype to become osteoblast like cells [3]. The phenotypes of these cells play a role in the development of calcification in the aortic valves [4].

Angiotensin II is a hormone in the body that has been implicated …

Antibacterial Properties Of A Cationic Imidazolium-Containing Poly(Ionic Liquid), Kaitlyn P. Brickey

Biomedical Engineering Undergraduate Honors Theses

Poly(ionic liquids), or PILs, have been shown to have a number of biological applications as ligands, drug delivery vehicles, and nonviral DNA delivery mechanisms. Additionally, PILs have been proven to be efficient antibacterials. Imidazolium-containing PILs have promising results in antibacterial studies, but relating to their chain and charge density, only the effects of mono- & bis-imidazolium PILs have been sufficiently described in literature. The work detailed in this thesis aimed to further existing research on the effect of chain density by controlling the UV-initiator immobilization time. The effects of chain density were investigated by grafting poly(vinylimidazolium chloride) onto SiO_{2 …}

Regeneration Of The Ventricular Endocardium Within Acellular Whole Rabbit Hearts Using A Layer-By-Layer Seeding Method, Clayton Lewis Compton

All Theses

In the United States, 1 out of every 9 death certificates in 2013 referenced heart failure.1 Despite the outstanding need of treatment options for heart failure, heart transplantation remains the optimal treatment method. However, there is a severe shortage of donor hearts available for transplantation.2 Other available treatment options are not ideal because they do not fully restore function and are associated with creating other complications.3 Thus, there is a need for developing a living tissue engineered whole heart for transplantation to provide an alternative option for patients on the waitlist to receive a donor heart.

Our solution is to …

Experimental And Model-Based Terahertz Imaging And Spectroscopy For Mice, Human, And Phantom Breast Cancer Tissues, Tyler Bowman

Graduate Theses and Dissertations

The goal of this work is to investigate terahertz technology for assessing the surgical margins of breast tumors through electromagnetic modeling and terahertz experiments. The measurements were conducted using a pulsed terahertz system that provides time and frequency domain signals. Three types of breast tissues were investigated in this work. The first was formalin-fixed, paraffin-embedded tissues from human infiltrating ductal and lobular carcinomas. The second was human tumors excised within 24-hours of lumpectomy or mastectomy surgeries. The third was xenograft and transgenic mice breast cancer tumors grown in a controlled laboratory environment to achieve more data for statistical analysis.

Experimental …

Computational Fluid Dynamics Model For Air Velocity Through A Poultry Transport Trailer In A Holding Shed, Christian Heymsfield

Graduate Theses and Dissertations

Broiler production in Arkansas was valued at over $3.6 billion in 2013 (University of Arkansas Division of Agriculture Cooperative Extension Service). Consequently, improvement in any phase of the production process can have significant economic impact and animal welfare implications. One area of concern for the poultry industry is thermal stress experienced by the birds after arrival at the processing plant and before they are taken in to be processed, during which time they are left to wait in holding sheds. Various cooling strategies exist to mitigate heat stress in holding sheds, but in most cases it is unlikely that they …

Longitudinal Tracking Of Physiological State With Electromyographic Signals., Robert Warren Stallard

Electronic Theses and Dissertations

Electrophysiological measurements have been used in recent history to classify instantaneous physiological configurations, e.g., hand gestures. This work investigates the feasibility of working with changes in physiological configurations over time (i.e., longitudinally) using a variety of algorithms from the machine learning domain. We demonstrate a high degree of classification accuracy for a binary classification problem derived from electromyography measurements before and after a 35-day bedrest. The problem difficulty is increased with a more dynamic experiment testing for changes in astronaut sensorimotor performance by taking electromyography and force plate measurements before, during, and after a jump from a small platform. A …

In-Vitro Simulation Of Acute Ischemic Stroke, Paolo Garcia

Biomedical Engineering Undergraduate Honors Theses

Acute ischemic stroke (AIS) is a condition that involves the occlusion of a blood vessel within the brain, effectively preventing the passage of oxygen and nutrients. AIS is highly prevalent in the United States, where nearly 795,000 strokes happen per year and 87% of those are ischemic. From a medical standpoint, the obstructing clot can be removed with the use of a stroke retrieval device. However, a need arises for testing the aforementioned devices on a patient’s specific vascular geometries in order to increase the likelihood of a successful procedure. Outlined is a process for developing a physical simulation of …

Development Of An In Vitro Platform For The Exploration Of Skeletal Muscle Cell Mechanobiology, Sydney Spradlin

Biomedical Engineering Undergraduate Honors Theses

Muscles have the natural ability to regenerate when damaged. This works to keep the body functioning, unless this ability is overwhelmed. Volumetric muscle loss (VML) occurs when a substantial amount of a muscles mass is lost. This leads to the development of scar tissue, and often a loss of function. In order to find a solution for this condition, in vitro models are needed to explore the mechanobiology of skeletal muscle cells. Two platforms were developed in this study, to explore 3 factors: orientation, strain, and supporting structure. One platform used fibronectin stamped lanes on PDMS to encourage cell growth …

Pressure Acquisition System For In Vitro Mitral Valve Analysis, Laura Peck

Biomedical Engineering Undergraduate Honors Theses

In vitro testing of the mitral valve chordae tendineae is utilized to aid in the understanding of the stresses that occur in vivo and improve upon surgical solutions that exist for mitral valve repair. This project aimed to design the water control system for a left heart simulation chamber, as well as the pressure acquisition inside the chamber. A solenoid valve was utilized to control the water supply to the tank and was powered utilizing National Instruments software. National Instruments hardware and software was also used with the pressure transducer in order to obtain pressure readings from the chamber. The …