Health and Medical Physics Commons^™

The Disability Burden Associated With Stroke Emerges Before Stroke Onset And Differentially Affects Blacks: Results From The Health And Retirement Study Cohort, Benjamin D. Capistrant, Nicte I. Mejia, Sze Yan Liu, Qianyi Wang, M. Maria Glymour

Department of Public Health Scholarship and Creative Works

Background.

Few longitudinal studies compare changes in instrumental activities of daily living (IADLs) among stroke-free adults to prospectively document IADL changes among adults who experience a stroke. We contrast annual declines in IADL independence for older individuals who remain stroke-free to those for individuals who experienced a stroke. We also assess whether these patterns differ by sex, race, or Southern birthplace. Methods.

Health and Retirement Study participants who were stroke-free in 1998 (n = 17,741) were followed through 2010 (average follow-up = 8.9 years) for self- or proxy-reported stroke. We used logistic regressions to compare annual changes in odds of …

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 study is …

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 …

Evaluating Programs That Address Ideological Issues: Ethical And Practical Considerations For Practitioners And Evaluators, Lisa D. Lieberman, Michael C. Fagan, Brad L. Neiger

Department of Public Health Scholarship and Creative Works

There are important practical and ethical considerations for organizations in conducting their own, or commissioning external, evaluations and for both practitioners and evaluators, when assessing programs built on strongly held ideological or philosophical approaches. Assessing whether programs “work” has strong political, financial, and/or moral implications, particularly when expending public dollars, and may challenge objectivity about a particular program or approach. Using a case study of the evaluation of a school-based abstinence-until-marriage program, this article discusses the challenges, lessons learned, and ethical responsibilities regarding decisions about evaluation, specifically associated with ideologically driven programs. Organizations should consider various stakeholders and views associated …

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

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 studies. The [59Fe]-SPIONs were evaluated …

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

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

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

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

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

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

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

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 …

Lessons From The Trenches: Meeting Evaluation Challenges In School Health Education, Michael Young, George Denny, Joseph Donnelly

Department of Public Health Scholarship and Creative Works

BACKGROUND: Those involved in school health education programs generally believe that health education programs can play an important role in helping young people make positive health decisions. Thus, it is to document the effects of such programs through rigorous evaluations published in peer‐reviewed journals.

METHODS: This paper helps the reader understand the context of school health program evaluation, examines several problems and challenges, shows how problems can often be fixed, or prevented, and demonstrates ways in which challenges can be met. A number of topics are addressed, including distinguishing between curricula evaluation and evaluation of outcomes, types of evaluation, identifying …

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

Graduate 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 …

Relationships And Context As A Means For Improving Disease Prevention And Sexual Health Messages, Lisa D. Lieberman

Department of Public Health Scholarship and Creative Works

In many ways, the HIV epidemic changed the discourse about sex in the United States and worldwide (Ehrhardt, 1992; Everett, 1986) and continues to drive approaches to sex education. After a period of rapid growth in the late 1980s (approximately 150,000 new infections per year), by the late 1990s, HIV rates in the United States slowed to some 40,000 new infections annually (Centers for Disease Control and Prevention [CDC], 2001), and new HIV infections continue to hover around that number. The first successful examples of behavior change that resulted in decreased HIV transmission emerged from …

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 addressed by developing …

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 …

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

Doctoral Dissertations

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. …