Biomedical Engineering and Bioengineering Commons^™

Fluorescence Cryotomography For Preclinical Validation: Applications In Gene Therapy And Fluorescence-Guided Surgery, Caleb Y. J. Kwon

Dartmouth College Ph.D Dissertations

Fluorescence imaging has become a powerful tool in biomedical research and clinical practice, offering molecular specificity and high sensitivity for visualizing biological processes in real time, However, the successful translation of novel fluorescent probes or medicines from preclinical development to clinical applications requires rigorous validation of their biodistribution and target specificity. Traditional methods for assessing performance, such as bulk excised organ analysis or two-dimensional histology, provide limited information as they cannot capture the complete, organism-wide distribution of these probes or medicines. This thesis aims to improve this analysis pipeline through the application and optimization of fluorescence cryotomography for quantitative, high-resolution …

High-Throughput Robotic Ethanol Inhibition Assays For Engineered Thermophilic Biofuel Strains, Kevin He, Daniel Olson, Marybeth Maloney, Anthony Lanahan

Wetterhahn Science Symposium Posters

Ethanol stress assays are commonly used to evaluate microbial tolerance, metabolic adaptation, and fermentation performance. However, manual liquid handling introduces variability across replicate wells and small-volume pipetting steps, limiting reproducibility and throughput. This study developed an automated OT-2 robotic workflow to generate replicated ethanol concentration gradients for high-throughput inhibition assays in engineered thermophilic biofuel strains. Kinetic plate-reader measurements were used to quantify ethanol-dependent growth responses under anaerobic fermentation conditions. The reasearch question is: How do engineered thermophilic biofuel strains differ in ethanol-dependent growth inhibition under anaerobic fermentation conditions, and can automated robotic assays improve the reproducibility of these measurements? Can …

Quantitative Fluorescence Imaging Using A Paired Agent Approach For Improving Surgical Decision Making, Sanjana Pannem

Dartmouth College Ph.D Dissertations

Surgical resection remains to be the cornerstone of treatment for most solid tumors, where the primary objective is to remove all visible and microscopic disease. However, the extent of tumor resection is inherently limited by the surgeon’s ability to distinguish tumor from normal tissue, intraoperatively. As a result, positive surgical margins (PSM), where residual tumor remains after surgery, are a common occurrence and are associated with increased recurrence, need for adjuvant therapies, dismal patient outcomes, and high healthcare costs.

Fluorescence guided surgery (FGS) has emerged as a promising technique to enhance intraoperative visualization of tumors and may help reduce the …

Advancing Computational Analysis Of Fluorescence Imaging For Head And Neck Cancer Surgical Guidance, Yao Chen

Dartmouth College Ph.D Dissertations

The main goal of surgery for head and neck squamous cell carcinoma (HNSCC) is to remove the tumor completely while preserving as much healthy tissue as possible to enhance patient survival and reduce complications. However, achieving clear surgical margins is difficult due to the complex anatomy of the head and neck and the reliance on a surgeon’s visual and tactile assessments. Recently, near-infrared (NIR) fluorescence molecular imaging has shown potential for better tumor visualization during surgery, using targeted imaging agents like epidermal growth factor receptor (EGFR) probes. This has led to the development of fluorescence-guided surgery (FGS), which helps surgeons …

Methods For Radiation-Sparing Navigation In Endovascular And Spine Surgery, William Ross Warner

Dartmouth College Ph.D Dissertations

Modern surgical navigation systems improve procedural accuracy, limit complications, and can reduce reliance on intraoperative ionizing radiation, yet their adoption remains uneven across surgical domains. Informed by clinical immersion, this thesis identifies and addresses two unmet needs revealed through contrasting image-guidance practices in endovascular and spine surgery, where existing guidance techniques are costly, intermittent, or fundamentally limited. Specifically, these needs include (1) the absence of radiation-sparing navigation techniques for endovascular procedures, which rely heavily on 2D x-ray angiography, and (2) the need for dynamic registration methods in open spine surgery, where navigation accuracy can degrade after initial registration and intraoperative …

Volumetric Wear Analysis Of Polyethylene Orthopedic Liners Using Point Clouds, Gabriel Landi

Dartmouth College Master’s Theses

In vivo wear of ultra-high molecular weight polyethylene (UHMWPE) orthopedic bearings represents a major problem in shoulder and knee arthroplasty, with significant amounts of devices failing due to the complication itself, and even more due to associated reasons for retrieval, including aseptic loosening. However, quantification of UHMWPE wear has largely been limited to linear and in vitro volumetric analyses, obscuring the understanding of the amount of clinically relevant material loss. This study proposes new methods to measure articular, rim, and backside surfaces of retrieved shoulder and knee UHMWPE liners, centered around the coordinate measuring machine (CMM)-based collection of high density …

Training A Cellpose Model For T-Cell Cytoplasm And Nucleus Segmentation, William Laws, Matthew Lindley, Irene Georgakoudi

Wetterhahn Science Symposium Posters

Accurate single-cell segmentation of cytoplasm from nucleus in autofluorescence images is critical for quantifying cellular metabolism using the optical redox ratio (FAD / FAD+NAD(P)H). However, automated cytoplasmic segmentation of T cell two-photon excitation fluorescence images remains challenging due to low signal-to-noise ratio, small cell size, and variability in cell brightness across imaging conditions. Here, we present a pipeline combining a custom-trained Cellpose-SAM model with an adapted cytoplasmic post-processing algorithm (CPPA) for automated single-cell metabolic analysis of T cell NAD(P)H autofluorescence images. Raw 2048×2048 pixel images were spatially binned 4×4 in MATLAB to improve signal-to-noise ratio and reduce processing time. A …

Advancing Cns Tumor Management: Novel Modalities In Surgery, Radiation, And Chemotherapy, Armin David Tavakkoli

Dartmouth College Ph.D Dissertations

Most tumors affecting the brain and spine are managed through a combination of surgical resection, radiation, and chemotherapy; however, operative morbidity from invasive surgery, the narrow therapeutic window of conventional radiotherapy, and poor blood-brain barrier penetration of systemic agents are critical barriers that hinder long term tumor control. This thesis presents three complementary strategies to advance brain and spine tumor therapy. First, we investigate laser interstitial thermal therapy (LITT) in the treatment of spinal tumors with metastatic epidural spinal cord compression, replacing “separation surgery” with a minimally invasive, image-guided approach that maximizes tumor ablation while preserving neurologic function. Second, we …

Design And Validation Of A Novel Patterned Microfluidic Culture Platform For Hipsc-Cm Maturation, Anisia Gabriela Țiplea

Dartmouth College Master’s Theses

Adult cardiomyocytes (CMs) are among the most challenging cells to culture in vitro, given their poor adherence to plastic culture wells and poor maturation outside the native extracellular matrix (Narkar et al., 2022). Human induced pluripotent stem cell-derived CMs (hiPSC-CMs) offer a viable alternative to study heart development and disease progression. While not comparable to adult CMs in their maturity (Narkar et al., 2022), they mimic the clinical phenotypes of heart failure and are more feasible to culture. Nevertheless, hiPSC-CMs require specialized culture conditions that cannot be achieved with 2D static culturing, which fail to replicate native tissue environments (X. …

Flash Effect Is Diminished By Daily Fractionation Of Electron Rt In Mouse Skin, Aleksandra Ilina, William S. Thomas, Xu Cao, Matthew S. Reed, Kendall Jarvis, Albert Van Der Kogel, Nathaniel Van Asselt, Wesley S. Culberson, Brian W. Pogue

Dartmouth Scholarship

Objective. While FLASH radiotherapy is known to reduce skin damage in vivo from ultra-high dose rate (UHDR) irradiation relative to conventional dose rates (CDR), it is not clear whether this sparing is preserved when delivered as fractionated. This study was designed to directly assess whether three daily fractions would maintain the sparing effects in murine leg models and preserve the murine skin sparing with single fraction treatments. Approach. C57Bl/6j female mice were irradiated with 9 MeV UHDR and CDR beams from a FLASH-capable Mobetron system, in a dose escalation study with doses ranging from single dose 22–30 Gy in a …

An Active Electrode Electrical Impedance Tomography Probe For Intraoperative Surgical Margin Assessment In Robotic-Assisted Radical Prostatectomies, Allaire Doussan

Dartmouth College Ph.D Dissertations

Prostate cancer is the most common cancer among men and the second most common cancer overall in the United States, with 288,300 new cases in 2023 and 1.4 million globally. Approximately 40.5% of patients undergo radical prostatectomy (RP), where the primary goal is complete tumor removal while preserving neurovascular structures and urethral length to maintain erectile function and continence. Achieving this balance contributes to variable positive surgical margin (PSM) rates, reported between 4–48% (average 21%). PSMs increase recurrence risk and often necessitate costly, noxious adjuvant therapies. Despite this there is no widely adopted method for intraoperative margin assessment in real …

Advancing Novel Contrast Agents For Applications In Fluorescence-Guided Neurosurgery Using Fluorescence Cryotomography, Augustino Vittorio Scorzo

Dartmouth College Ph.D Dissertations

Fluorescence guided surgery (FGS) is an emerging surgical technique that aims to help surgeons identify tissue types to assist in surgical decision making - ideally providing “cut-by-color” guidance. A primary application for this approach is the identification of tumor tissue to achieve more accurate and complete tumor removal while simultaneously minimizing damage to surrounding normal tissue. The cornerstone of tumor visualization for FGS is the administration of fluorescent contrast agents, or in some cases metabolic precursors, designed to accumulate specifically in tumor tissue, and a wide range of agents that use different targeting mechanisms are currently under investigation. Although these …

Mechanistic Insights Into The Flash Effect: The Role Of Oxygen And Radiation Chemistry In Ultra-High Dose Rate Radiation Therapy, Jacob Pierce Sunnerberg

Dartmouth College Ph.D Dissertations

The development of new cancer therapies focuses on widening the therapeutic ratio between tumor control and normal tissue toxicity. Over the last decade, ultra-high dose rate (UHDR) radiation therapy, commonly known as FLASH radiotherapy (FLASH-RT), has shown promising potential to reduce normal tissue toxicity while maintaining tumor control. However, the underlying mechanisms of the FLASH effect remain poorly understood. This thesis explores the radiation-chemical basis of FLASH-RT, focusing on the role of oxygen and reactive oxygen species in modulating biological outcomes.

A comprehensive set of in vitro studies demonstrated that UHDR delivery significantly alters radiation chemistry compared to conventional dose …

Intraoperative Dynamic Contrast-Enhanced Fluorescence Imaging For Navigating Open Orthopedic Surgeries, Yue Tang

Dartmouth College Ph.D Dissertations

Infection following trauma is one of the most prevalent and challenging complications faced by orthopedic surgeons. Inadequate tissue perfusion plays a critical role in this complication, as poorly perfused bone can be a nidus for bacterial biofilm formation and promote resistance to antibiotic treatments. Consequently, the management of open fractures and fracture-related infections relies on aggressive and thorough debridement to remove all poorly perfused bone. This thesis focuses on developing an indocyanine green (ICG)-based dynamic contrast-enhanced fluorescence imaging (DCE-FI) to objectively measure bone perfusion during open orthopedic surgeries and guide surgical debridement of devitalized bone.

Novel methodologies were developed to …

Metabolite Analysis To Understand Factors Limiting Microbial Fermentation At High Substrate Concentrations, Bishal D. Sharma

Dartmouth College Ph.D Dissertations

Clostridium thermocellum, a thermophilic anaerobic bacterium, holds promise as a biocatalyst for conversion of lignocellulosic biomass into biofuels. This microbe has been subjected to various metabolic engineering strategies, including the deletion of genes encoding secondary fermentation products such as H₂, formate, acetate, and lactate, as well as the expression of heterologous genes to redirect carbon flux toward ethanol production. Despite these efforts, achieving economically viable ethanol titers remains a challenge. We hypothesized that studying how intracellular metabolite concentrations change as fermentation stops could reveal metabolic bottlenecks or regulatory mechanisms limiting ethanol production at high titers. However, metabolomics studies at …

Optical Methods For Time-Resolved Dosimetry And Oximetry Of Ultra-High Dose Rate Radiation Therapy, Megan A. Clark

Dartmouth College Ph.D Dissertations

Radiotherapy (RT) is a cornerstone method used to treat over 50% of the 2 million new cancer diagnoses each year in the United States. The success of RT directly relies on an optimal balance between maximizing the dose to the tumor while minimizing dose to surrounding normal tissues. Achieving this balance is often challenging due to underlying radiation transport and the presence of anatomical constraints that limit the beam delivery geometry. In turn, minimizing healthy tissue toxicity prevents use of a more aggressive tumor killing approach, and even in curative cases may decrease the patient’s quality of life due to …

Application-Driven Materials Development Of Solid-State Conductive Composites Of Ultra-High Molecular Weight Polyethylene, Peder Solberg

Dartmouth College Ph.D Dissertations

Ultra-high molecular weight polyethylene (UHMWPE) is a linear long chain homopolymer valued for its toughness, wear resistance, and chemical inertness. In the medical field, these properties make it the material of choice for bearing surfaces despite recognized tradeoffs between wear resistance, toughness, and oxidation resistance. Electrically conductive composites of UHMWPE show promise to enable new types of smart and active load-bearing implants in a future of personalized medicine, if beneficial properties can be maintained with the addition of solid-state additives.

Clinical need-finding conducted through Dartmouth’s Training Program in Surgical Innovation revealed several potential applications for conductive, load-bearing polymers. These include: …

The Implementation And Miniaturization Of A New Current Source Into The Consolidated Layout Of An Electrical Impedance Tomography Probe With A Novel Approach To Electrode Layout, Katherine M. Bullion

Dartmouth College Master’s Theses

Prostate cancer is the most highly diagnosed form of cancer in male subjects in the United States. As a result, over 100,000 radical prostatectomies are performed annually in the US [1]. However, it is currently very difficult for surgeons to confirm that all impacted tissues have been effectively removed from the patient. Positive surgical margins are an independent risk factor for the recurrence of cancer, yet currently there is no method to efficiently, intraoperatively assess the status of surgical margins during a radical prostatectomy. There is a need for a new tool that is small enough to fit into a …

The Accurate Conversion Of Biological Experiments From Cesium Irradiation To X-Ray Irradiation: The Significance, Problems, And The Future Of Experimental Radiation Research, Gretchen Carpenter

Dartmouth College Master’s Theses

Preclinical small animal irradiation studies, once conducted on Cesium irradiators, are increasingly being performed with X-ray-based irradiators. The transition stems from concerns regarding national security risks, making X-ray irradiators which are compact and easy to operate an enticing alternative. However, questions regarding the relative biological effectiveness between the two sources have revealed a lack of adequate dosimetric characterization of X-ray beams, standardized protocol for dose calibration, and thorough understanding of experimental biological parameters. A literature review conducted on orthovoltage irradiators has revealed that there are over 54 different types of beam structures used, a dramatic departure from the one uniform …

Smart Toys For Sensing And Soothing Distress In Pediatric Patients, Jonathan Daniel Bonilla

Dartmouth College Master’s Theses

This thesis develops and evaluates child-centered technologies to support remote monitoring of pediatric patients, with an emphasis on childhood cancer and pediatric chronic pain. For these and many other health conditions, current therapies tend to focus on treating physical symptoms yet neglect the psycho-emotional aspects of managing the illness. However, such mental states play a major role in recovery. Research has shown that cancer patients with better mental health have better prognoses, higher possibilities of remission, and faster healing processes, while chronic pain patients with better mental health report lower levels of pain. To enable more personalized, continuous, and scalable …

Integrated Reference Single-Cell Rna Seq Atlas Of Healthy Human Female Tissues To Expand The Computational Drug Target Discovery Approaches For Female-Directed Non-Hormonal Contraceptives, Zhanel Nugmanova

Dartmouth College Master’s Theses

The ovary is vital for fertility and the maintenance of endocrine homeostasis. It contains heterogeneous cell populations, including oocyte, granulosa, stromal, endothelial, smooth muscle, and immune cell types. Creating a harmonized dataset that enables cross-tissue comparisons, including the ovary, is essential for identifying genes specific to ovarian cell types and for facilitating drug discovery for contraception and fertility purposes. There are very few resources that allow for the assessment of the expression of potential gene targets across human and mouse tissues for female-directed non-hormonal contraceptives. This is because most of these publicly available datasets are from post-menopausal women. Through our …

Preclinical Examination Of A Nerve Specific Fluorophore Using Ex Vivo Human Tissues, Logan Michael Bateman

Dartmouth College Master’s Theses

Fluorescence-guided surgery (FGS) is a nascent field which seeks to improve patient safety and surgical outcomes using fluorescent agents known as fluorophores. Fluorophores are molecules which upon excitation with a specific wavelength of light emit a photon of a specific wavelength which can be detected using a modified camera system. Creation and translation of a fluorophore for clinical use is a costly, laborious, and time intensive process. Only a handful of fluorophores have received FDA approval and they required multiple years of tightly regulated clinical trials. Prior to these first-in-human studies these agents are subject to a litany of preclinical …

Patterned Magnetic And Plasmonic Nanostructures In Microfluidics For Extracellular Vesicle Screening And Drug Loading, John H. Molinski

Dartmouth College Ph.D Dissertations

Extracellular vesicles (EVs), once dismissed as shuttles for cellular waste, have emerged as vital nanoscale biomolecules, facilitating intercellular communication through transfer of host-cell specific molecular cargo. Tumor-derived EVs, released by cancer cells, hold potential as diagnostic biomolecules due to their links to cancer cells, abundance within biofluids, and potential for direct extraction and detection. More broadly, EVs from a wide array of cellular origins have been explored as therapeutic carriers, stemming from their innate function as cargo carriers, high biocompatibility, and their ability to evade immune detection. However, harnessing EVs for diagnostic or therapeutic applications necessitates efficient isolation, purification, and …

Development Of Novel Radiotherapy Treatment Monitoring And Quantitative Cherenkov Surface Dosimetry For Diverse Populations, Savannah M. Decker

Dartmouth College Ph.D Dissertations

In the U.S. alone, nearly 2 million people will be diagnosed with cancer annually, and over half of them will receive radiation therapy throughout the course of their care. While widely regarded as safe, radiation therapy presents unique challenges that other procedures, such as surgery, lack. Namely, the invisible nature of the radiation itself makes it impossible to directly visualize treatment. Many immobilization and localization techniques exist to minimize the chance of incorrect radiation dose delivery, yet incidents still occur. Within the last decade, Cherenkov imaging has emerged as a new radiation therapy delivery verification technique. Cherenkov imaging is unique …

Surgical Navigation In Image-Guided Transoral Robotic Surgery, Yuan Shi

Dartmouth College Ph.D Dissertations

Transoral robotic surgery (TORS) is a minimally invasive approach in treating head and neck cancers and has demonstrated improved surgical outcomes with reduced morbidity when compared to traditional open surgery. However, the lack of haptic feedback makes it more difficult to assess the tumor extent and locate critical structures (e.g., artery and nerves). In standard-of-care TORS, preoperative imaging is used as guidance; however, it becomes inaccurate intraoperatively: the patient’s neck is hyper-extended, surgical instruments are introduced, and soft tissues deform significantly. As a result, the surgeon is required to mentally predict intraoperative deformation, which can lead to bleeding complications and …

Toward Electrical Impedance Sensing Surgical Drill For Tissue Boundary Detection, Harshavardhan Devaraj

Dartmouth College Ph.D Dissertations

Dental implantation is an increasingly common procedure used to treat missing teeth. However, surgical drilling to place the implant poses a high risk of injury to critical anatomy, such as inferior alveolar nerve injury or maxillary sinus perforation. A real-time surgical feedback system sensing proximity of these critical anatomy could reduce injury risks. This dissertation investigates the development of such a system that incorporates an electrical impedance sensor into the tip of a surgical drill.

A simulation framework based on finite element method (FEM) was developed to optimize the sensor as it approached a high impedance boundary. The accuracy of …

Towards A Wearable Device For Measuring Impedance Plethysmography Of The Radial Artery, Pritom Chowdhury

Dartmouth College Master’s Theses

Recent advancements in bioimpedance technology have demonstrated significant promise in the application of cardiac health monitoring. This research explores the design and development of a forearm-based wearable bioimpedance device for non-invasive measurement of heart rate and respiratory rate at an accuracy level comparable to medical-grade monitors. It utilizes a tetrapolar electrode configuration to analyze bioimpedance changes in the radial artery due to blood flow.

An ongoing aspect of this work involves the preliminary development of an embedded framework intended to integrate signal generation, acquisition, and processing within the device to achieve compact and efficient system design, anticipated to contribute to …

Investigating The Role Of Anesthesia In Radiation Therapy, William Walter Daley

ENGS 88 Honors Thesis (AB Students)

Purpose:

Cancer claims 7.6 million lives worldwide annually, affecting millions more. Conventional (CONV) radiation therapy (RT) is a key weapon in the oncological arsenal. A novel mode of radiation delivery, utilizing ultra-high dose rates (UHDR), is associated with enhancing the RT therapeutic ratio by selectively sparing normal tissue without sparing tumor tissue. However, there are many roadblocks to the clinical implementation of UHDR RT —namely the lack of standardization of experimental conditions and the inconsistency of published and unpublished results. This thesis investigates variables that affect preclinical biological outcomes to radiation.

Materials/Methods:

Eight groups of 10 C57BL/6 mice were stratified …

An Fpga-Based Eit System For Deep Space Medical Imaging, Kendall R. Farnham

Dartmouth College Ph.D Dissertations

Dangers associated with high radiation and microgravity exposure in space are critical challenges inhibiting us from exploring deep space and pursuing long-duration missions, as current medical systems are unable to monitor, diagnose, or treat tissue injury within physical spacecraft constraints and communication limits. Ultrasound (US) is the current imaging system used on the International Space Station, but this technology relies on telemedical support (or onboard artificial intelligence/autonomous capabilities) for both operation and diagnosis, posing challenges for crews isolated in deep space. Electrical impedance tomography (EIT) is a non-invasive, non-ionizing technology that produces images of the electrical properties of tissues and …

Advancements In Sarcoma- And Nerve-Specific Fluorescence Imaging For Surgical Guidance, Kendra A. Hebert

Dartmouth College Master’s Theses

Fluorescence guided surgery (FGS) is an evolving field that aims to improve patient outcomes by using fluorophores to identify important tissues during surgery, such as tumors and nerves. In this thesis work, we explored different methods of identifying nerve and tumor tissues for FGS and a novel fluorescence-based method to determine the depths of these structures.

Researchers have explored using fluorescence guided surgery for surgical resection of cancerous tissues, including recent work by our group focusing on identifying soft tissue sarcomas with ABY-029, an epidermal growth factor receptor targeting probe. However, our preclinical and clinical work shows no single reporter …