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Articles 1 - 9 of 9
Full-Text Articles in Medicine and Health Sciences
Hybrid Pet/Mri Nanoparticle Development And Multi-Modal Imaging, David Hoffman
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
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
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 …
Pain Management And Menopausal Health Outcomes In Multiple Sclerosis, Rachel Jawahar
Pain Management And Menopausal Health Outcomes In Multiple Sclerosis, Rachel Jawahar
Theses and Dissertations
Background: Previous studies have addressed multiple sclerosis (MS) symptom management and improved health-related quality of life (HrQOL). Yet lowered estrogen levels in post-menopasual women with MS may further worsen physical function and symptomology and not all types of pain management have been examined. Objectives: For post-menopausal women with MS, we evaluated the extent to which smoking is associated with worsened health outcomes and HrQOL, and the extent to which menopausal hormone treatment (MHT) improves health outcomes and HrQOL. For all adult men and women with clinically diagnosed MS, we systematically reviewed pharmacological and non-pharmacological strategies for the reduction of pain. …
Automatic Block-Matching Registration To Improve Lung Tumor Localization During Image-Guided Radiotherapy, Scott Robertson
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
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 …
Correlates And Predictors Of Risky Sexual Partnering, Jennifer Nield
Correlates And Predictors Of Risky Sexual Partnering, Jennifer Nield
Theses and Dissertations
Introduction: Sexually Transmitted Diseases, including HIV/AIDS, continue to be a major burden in the United States. Sexual partnering behaviors contribute to the spread of STDs. Sexual concurrency has been shown to exponentially increase STD prevalence in populations. Serial monogamy with short periods between sexual partners also introduces risk. Methods: We identified sexually active men and women from the 2006-2010 National Survey of Family Growth (NSFG) and used sub sets for each particular study. Sexual partnering was defined as being concurrent, serially monogamous or monogamous in the previous year. Polytomous logistic regression models were developed to evaluate the associations between age …