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Determining The Detective Quantum Efficiency (Dqe) Of X-Ray Detectors In Clinical Environments, Terenz R. Escartin 2017 The University of Western Ontario

Determining The Detective Quantum Efficiency (Dqe) Of X-Ray Detectors In Clinical Environments, Terenz R. Escartin

Electronic Thesis and Dissertation Repository

According to Health Canada, dental and medical radiography accounts for more than 90% of total man-made radiation dose to the general population. Ensuring patients receive the health benefits of diagnostic x-ray imaging without use of higher radiation exposures requires knowledge and understanding of the detective quantum efficiency (DQE). Currently, the DQE is not measured in clinics because it requires specialized instrumentation and specific DQE-expertise to perform an accurate analysis. In this regard, the goals of this thesis were to: 1) address the limitations of measuring the DQE in clinical environments that affects the accuracy of the measurement; 2) develop and ...


An Algorithm To Improve Deformable Image Registration Accuracy In Challenging Cases Of Locally-Advanced Non-Small Cell Lung Cancer, Christopher L. Guy 2017 Virginia Commonwealth University

An Algorithm To Improve Deformable Image Registration Accuracy In Challenging Cases Of Locally-Advanced Non-Small Cell Lung Cancer, Christopher L. Guy

Theses and Dissertations

A common co-pathology of large lung tumors located near the central airways is collapse of portions of lung due to blockage of airflow by the tumor. Not only does the lung volume decrease as collapse occurs, but fluid from capillaries also fills the space no longer occupied by air, greatly altering tissue appearance. During radiotherapy, typically administered to the patient over multiple weeks, the tumor can dramatically shrink in response to the treatment, restoring airflow to the lung sections which were collapsed when therapy began. While return of normal lung function is a positive development, the change in anatomy presents ...


Postural Responses To Perturbations Of The Vestibular System During Walking In Healthy Young And Older Adults, Jung Hung Chien 2015 University of Nebraska Medical Center

Postural Responses To Perturbations Of The Vestibular System During Walking In Healthy Young And Older Adults, Jung Hung Chien

Theses & Dissertations

It has been shown that approximate one-third of US adults aged 40 years and older (69 million US citizens) have some type of vestibular problems. These declining abilities of the vestibular system affect quality of life. Difficulties in performing daily activities (dressing, bathing, getting in and out of the bed and etc.) have been highly correlated to loss of balance due to vestibular disorders. The exact number of people affected by vestibular disorders is still difficult to quantify. This might be because symptoms are difficult to describe and differences exist in the qualifying criteria within and across studies. Thus, it ...


Soup Consumption Is Associated With A Lower Dietary Energy Density And A Better Diet Quality In Us Adults, Yong Zhu, James Hollis 2014 University of Iowa

Soup Consumption Is Associated With A Lower Dietary Energy Density And A Better Diet Quality In Us Adults, Yong Zhu, James Hollis

Food Science and Human Nutrition Publications

Epidemiological studies have revealed that soup consumption is associated with a lower risk of obesity. Moreover, intervention studies have reported that soup consumption aids in body-weight management. However, little is known about mechanisms that can explain these findings. The objective of the present study was to investigate associations between soup consumption and daily energy intake, dietary energy density (ED), nutrient intake and diet quality. Adults aged 19–64 years who participated in the National Health and Nutrition Examination Surveys during 2003–8 were included in the study. Soup consumers were identified from the first dietary recall using the United States ...


Multi – Modality Molecular Imaging Of Adoptive Immune Cell Therapy In Breast Cancer, Fatma Youniss 2014 Virginia Commonwealth University

Multi – Modality Molecular Imaging Of Adoptive Immune Cell Therapy In Breast Cancer, Fatma Youniss

Theses and Dissertations

Cancer treatment by adoptive immune cell therapy (AIT) is a form of immunotherapy that relies on the in vitro activation and/or expansion of immune cells. In this approach, immune cells, particularly CD8+ T lymphocytes, can potentially be harvested from a tumor-bearing patient, then activated and/or expanded in vitro in the presence of cytokines and other growth factors, and then transferred back into the same patient to induce tumor regression. AIT allows the in vitro generation and activation of T-lymphocytes away from the immunosuppressive tumor microenvironment, thereby providing optimum conditions for potent anti-tumor activity. The overall objective of this ...


Multimodality Molecular Imaging Of [18f]-Fluorinated Carboplatin Derivative Encapsulated In [111in]-Labeled Liposome, Narottam Lamichhane 2014 Virginia Commonwealth University

Multimodality Molecular Imaging Of [18f]-Fluorinated Carboplatin Derivative Encapsulated In [111in]-Labeled Liposome, Narottam Lamichhane

Theses and Dissertations

Platinum based chemotherapy is amongst the mainstream DNA-damaging agents used in clinical cancer therapy today. Agents such as cisplatin, carboplatin are clinically prescribed for the treatment of solid tumors either as single agents, in combination, or as part of multi-modality treatment strategy. Despite the potent anti-tumor activity of these drugs, overall effectiveness is still hampered by inadequate delivery and retention of drug in tumor and unwanted normal tissue toxicity, induced by non-selective accumulation of drug in normal cells and tissues. Utilizing molecular imaging and nanoparticle technologies, this thesis aims to contribute to better understanding of how to improve the profile ...


Statistical Modeling Of Interfractional Tissue Deformation And Its Application In Radiation Therapy Planning, Douglas J. Vile 2014 Virginia Commonwealth University

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 ...


Hybrid Pet/Mri Nanoparticle Development And Multi-Modal Imaging, David Hoffman 2013 Virginia Commonwealth University

Hybrid Pet/Mri Nanoparticle Development And Multi-Modal Imaging, David Hoffman

Theses and Dissertations

The development of hybrid PET/MRI imaging systems needs to be paralleled with the development of a hybrid intrinsic PET/MRI probes. The aim of this work was to develop and validate a novel radio-superparamagnetic nanoparticle (r-SPNP) for hybrid PET/MRI imaging. This was achieved with the synthesis of superparamagnetic iron oxide nanoparticles (SPIONs) that intrinsically incorporated 59Fe and manganese iron oxide nanoparticles (MIONs) that intrinsically incorporated 52Mn. Both [59Fe]-SPIONs and [52Mn]-MIONs were produced through thermal decomposition synthesis. The physiochemical characteristics of the r-SPNPs were assessed with TEM, DLS, and zeta-potential measurements, as well as in imaging phantom ...


Characterization Of A Small Animal Spect Platform For Use In Preclinical Translational Research, Dustin Ryan Osborne 2013 Selected Works

Characterization Of A Small Animal Spect Platform For Use In Preclinical Translational Research, Dustin Ryan Osborne

Dustin Ryan Osborne

Imaging Iodine-125 requires an increased focus on developing an understanding of how fundamental processes used by imaging systems work to provide quantitative output for the imaging system. Isotopes like I-125 pose specific imaging problems that are a result of low energy emissions as well as how closely spaced those emissions are in the spectrum. This work seeks to characterize the performance of a small animal SPECT-CT imaging system with respect to imaging I-125 for use in a preclinical translational research environment and to understand how the performance of this system relates to critical applications such as attenuation and scatter correction ...


Positron Emission Tomography For Pre-Clinical Sub-Volume Dose Escalation, Christopher Bass 2013 Virginia Commonwealth University

Positron Emission Tomography For Pre-Clinical Sub-Volume Dose Escalation, Christopher Bass

Theses and Dissertations

Purpose: This dissertation focuses on establishment of pre-clinical methods facilitating the use of PET imaging for selective sub-volume dose escalation. Specifically the problems addressed are 1.) The difficulties associated with comparing multiple PET images, 2.) The need for further validation of novel PET tracers before their implementation in dose escalation schema and 3.) The lack of concrete pre-clinical data supporting the use of PET images for guidance of selective sub-volume dose escalations. Methods and materials: In order to compare multiple PET images the confounding effects of mispositioning and anatomical change between imaging sessions needed to be alleviated. To mitigate the ...


Principled Variance Reduction Techniques For Real Time Patient-Specific Monte Carlo Applications Within Brachytherapy And Cone-Beam Computed Tomography, Andrew Sampson 2013 Virginia Commonwealth University

Principled Variance Reduction Techniques For Real Time Patient-Specific Monte Carlo Applications Within Brachytherapy And Cone-Beam Computed Tomography, Andrew Sampson

Theses and Dissertations

This dissertation describes the application of two principled variance reduction strategies to increase the efficiency for two applications within medical physics. The first, called correlated Monte Carlo (CMC) applies to patient-specific, permanent-seed brachytherapy (PSB) dose calculations. The second, called adjoint-biased forward Monte Carlo (ABFMC), is used to compute cone-beam computed tomography (CBCT) scatter projections. CMC was applied for two PSB cases: a clinical post-implant prostate, and a breast with a simulated lumpectomy cavity. CMC computes the dose difference between the highly correlated dose computing homogeneous and heterogeneous geometries. The particle transport in the heterogeneous geometry assumed a purely homogeneous environment ...


Time Dependent Cone-Beam Ct Reconstruction Via A Motion Model Optimized With Forward Iterative Projection Matching, David Staub 2013 Virginia Commonwealth University

Time Dependent Cone-Beam Ct Reconstruction Via A Motion Model Optimized With Forward Iterative Projection Matching, David Staub

Theses and Dissertations

The purpose of this work is to present the development and validation of a novel method for reconstructing time-dependent, or 4D, cone-beam CT (4DCBCT) images. 4DCBCT can have a variety of applications in the radiotherapy of moving targets, such as lung tumors, including treatment planning, dose verification, and real time treatment adaptation. However, in its current incarnation it suffers from poor reconstruction quality and limited temporal resolution that may restrict its efficacy. Our algorithm remedies these issues by deforming a previously acquired high quality reference fan-beam CT (FBCT) to match the projection data in the 4DCBCT data-set, essentially creating a ...


Automatic Block-Matching Registration To Improve Lung Tumor Localization During Image-Guided Radiotherapy, Scott Robertson 2013 Virginia Commonwealth University

Automatic Block-Matching Registration To Improve Lung Tumor Localization During Image-Guided Radiotherapy, Scott Robertson

Theses and Dissertations

To improve relatively poor outcomes for locally-advanced lung cancer patients, many current efforts are dedicated to minimizing uncertainties in radiotherapy. This enables the isotoxic delivery of escalated tumor doses, leading to better local tumor control. The current dissertation specifically addresses inter-fractional uncertainties resulting from patient setup variability. An automatic block-matching registration (BMR) algorithm is implemented and evaluated for the purpose of directly localizing advanced-stage lung tumors during image-guided radiation therapy. In this algorithm, small image sub-volumes, termed “blocks”, are automatically identified on the tumor surface in an initial planning computed tomography (CT) image. Each block is independently and automatically registered ...


A Study Of Coverage Optimized Planning Incorporating Models Of Geometric Uncertainties For Prostate Cancer, Huijun Xu 2013 Virginia Commonwealth University

A Study Of Coverage Optimized Planning Incorporating Models Of Geometric Uncertainties For Prostate Cancer, Huijun Xu

Theses and Dissertations

A fundamental challenge in the treatment planning process of multi-fractional external-beam radiation therapy (EBRT) is the tradeoff between tumor control and normal tissue sparing in the presence of geometric uncertainties (GUs). To accommodate GUs, the conventional way is to use an empirical planning treatment volume (PTV) margin on the treatment target. However, it is difficult to determine a near-optimal PTV margin to ensure specified target coverage with as much normal tissue protection as achievable. Coverage optimized planning (COP) avoids this problem by optimizing dose in possible virtual treatment courses with GU models directly incorporated. A near-optimal dosimetric margin generated by ...


Optimization Of Radiation Therapy In Time-Dependent Anatomy, W. Tyler Watkins 2013 Virginia Commonwealth University

Optimization Of Radiation Therapy In Time-Dependent Anatomy, W. Tyler Watkins

Theses and Dissertations

The objective of this dissertation is to develop treatment planning techniques that have the potential to improve radiation therapy of time-dependent (4D) anatomy. Specifically, this study examines dose estimation, dose evaluation, and decision making in the context of optimizing lung cancer radiation therapy. Two methods of dose estimation are compared in patients with locally advanced and early stage lung cancer: dose computed on a single image (3D-dose) and deformably registered, accumulated dose (or 4D-dose). The results indicate that differences between 3D- and 4D- dose are not significant in organs at risk (OARs), however, 4D-dose to a moving lung cancer target ...


Decline In Health For Older Adults: Five-Year Change In 13 Key Measures Of Standardized Health, Paula Diehr 2012 University of Washington

Decline In Health For Older Adults: Five-Year Change In 13 Key Measures Of Standardized Health, Paula Diehr

Paula Diehr

Background. The health of older adults declines over time, but there are many ways of measuring health. It is unclear whether all health measures decline at the same rate or whether some aspects of health are less sensitive to aging than others. Methods. We compared the decline in 13 measures of physical, mental, and functional health from the Cardiovascular Health Study: hospitalization, bed days, cognition, extremity strength, feelings about life as a whole, satisfaction with the purpose of life, self-rated health, depression, digit symbol substitution test, grip strength, activities of daily living, instrumental activities of daily living, and gait speed ...


Epid-Based Dose Verification For Adaptive Radiotherapy, Joseph Gardner 2012 Virginia Commonwealth University

Epid-Based Dose Verification For Adaptive Radiotherapy, Joseph Gardner

Theses and Dissertations

Dose verification is a critical component of adaptive radiotherapy, as it provides a measurement of treatment delivery success. Based on the measured outcome, the plan may be adapted to account for differences between the planned dose and the delivered dose. Although placement of an EPID behind the patient during treatment allows for exit dosimetry which may be used to reconstruct the delivered patient dose via backprojection of the fluence, there have not been any studies examining the basic assumption of backprojection-based dose verification: that deviations between the expected and delivered exit fluences are totally caused by errors in the delivered ...


Fabrication And Characterization Of Thinner Solid-State Nanopores, Denis Forbi Tita 2012 University of Arkansas, Fayetteville

Fabrication And Characterization Of Thinner Solid-State Nanopores, Denis Forbi Tita

Theses and Dissertations

Solid State nanopores that are fabricated by the ion beam sculpting process and electron beam drilling have shown great promise as a sensing device for DNA and protein molecules. Even though biological pores such as the alpha-Haemolysin have been in use for quite some time, the use of solid state Nanopores in single biomolecule detection has been on the rise since the mid 1990s. Solid State nanopores have an advantage over biological pores in that they are more robust, stable, and can be sculpted to any desired size for use in translocation experiments. One of the major challenges in Nanopore ...


Validation Of 3'-Deoxy-3'-[18f]-Fluorothymidine Positron Emission Tomography For Image-Guidance In Biologically Adaptive Radiotherapy, Marian Axente 2012 Virginia Commonwealth University

Validation Of 3'-Deoxy-3'-[18f]-Fluorothymidine Positron Emission Tomography For Image-Guidance In Biologically Adaptive Radiotherapy, Marian Axente

Theses and Dissertations

Accelerated tumor cell repopulation during radiation therapy is one of the leading causes for low survival rates of head-and-neck cancer patients. The therapeutic effectiveness of radiotherapy could be improved by selectively targeting proliferating tumor subvolumes with higher doses of radiation. Positron emission tomography (PET) imaging with 3´-deoxy-3´-[18F]-fluorothymidine (FLT) has shown great potential as a non-invasive approach to characterizing the proliferation status of tumors. This thesis focuses on histopathological validation of FLT PET imaging specifically for image-guidance applications in biologically adaptive radiotherapy. The lack of experimental data supporting the use of FLT PET imaging for radiotherapy guidance is ...


Designing An Information-Experience Using Creativity Science & Tools, Stephanie Belhomme 2012 International Center for Studies in Creativity

Designing An Information-Experience Using Creativity Science & Tools, Stephanie Belhomme

Stephanie Belhomme

An “information-experience” encapsulated by a technological/digital audio-visual tool presents data and potentially meaningful information to prompt actionable knowledge concerning: “unspoken creative process elements;” their profound impacts on both how well our “physiology of creativity” functions but also; how well foundational creative thinking and behavioral prerequisites (energy, motivation, imagination, and ownership) are leveraged.

The product: 1) introduces the user to one component of the CPS (Creative Problem Solving) Facilitation Process - Exploring the Challenge; 2) features a content specific component which prompts exploration of the many correlations between societal, organizational / community, human physiological / behavioral data, and the direct relationships of these ...


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