Physical Sciences and Mathematics Commons^™

Volumetric Scintillation Dosimetry For Scanned Proton Beams, Daniel G. Robertson

Dissertations & Theses (Open Access)

Scanned beam proton therapy is a promising cancer treatment modality which is becoming more widely available with the increasing number of proton radiotherapy centers. Scanned proton beams can produce complex 3D dose distributions, presenting a challenge for adequate quality assurance testing. Because each scanned beam dose measurement requires the delivery of the entire field, multiple measurements can be time consuming. These quality assurance challenges limit the number of patients who can be treated with this modality. The overall objective of this project is to increase the safety and availability of complex proton therapy treatments by developing a fast volumetric scintillation …

Development Of A New Independent Monte Carlo Dose Calculation Quality Assurance Audit Tool For Clinical Trials, Austin M. Faught

Dissertations & Theses (Open Access)

Introduction: Commercially available treatment planning systems (TPS) may use a number of different radiation dose calculation algorithms during the planning process. The Radiological Physics Center (RPC), tasked with ensuring clinically comparable and consistent dose delivery amongst institutions participating in NCI funded multi-institutional clinical trials, has traditionally relied upon measurements to achieve this objective. As a supplement to the tools used by the RPC, an independent dose calculation tool is needed to determine patient dose distributions in three dimensions so as to act as a quality assurance tool for the dose calculations.

Methods: Multiple source models representing the output of Elekta …

Genetic Predictors Of Metabolic Side Effects Of Diuretic Therapy, Jorge L. Del Aguila

Dissertations & Theses (Open Access)

Thiazide diuretics are a recommended first-line monotherapy for hypertension (i.e.SBP>140 mmHg or DBP>90 mmHg). Even so, diuretics are associated with adverse metabolic side effects, such as hyperlipidemia, hyperglycemia and hypokalemia which increase the risk of developing type II diabetes. This thesis used three analytical strategies to identify and quantify genetic factors that contribute to the development of adverse metabolic effects due to thiazide diuretic treatment. I performed a genome-wide association study (GWAS) and meta-analysis of the change in fasting plasma glucose and triglycerides in response to HCTZ from two different clinical trials: the Pharmacogenomic Evaluation of Antihypertensive Responses …

Image-Guided Proton Therapy For Online Dose-Evaluation And Adaptive Planning, Joey P. Cheung

Dissertations & Theses (Open Access)

The main advantage for using protons in radiotherapy is their finite range in patients, allowing for potential improved sparing of normal tissues. However, this comes at a cost of increased sensitivity to range uncertainties. Density changes along the beam path will affect the proton range and the resultant dose distribution, making it difficult to estimate the impact of visible anatomic changes to the patient dose distribution. In order to better understand the effect of anatomy change on proton dose, some form of treatment-time verification is required and methods to correct for observed changes would be beneficial. Therefore, this project aims …

The Association Between The Il-1 Pathway, Isaac C. Wun

Dissertations & Theses (Open Access)

Cutaneous malignant melanoma (CMM) is a potentially lethal malignancy that warrants attention and further research, as it is known to that there is an increasing rate of incidence in theUnited States, and it is also known that exposure to UV light is its most crucial risk factor, and family history of melanoma is also an important risk factor. Melanoma is an aggressive and lethal cancer in humans. There are an estimated new 132,000 melanoma cases annually worldwide, and the trend has doubled in the past 20 years. However, attempts to treat melanoma have encountered considerable resistance and remained ineffective. The …

Evaluation Of Artifacts In Experimental Cine 4d Ct Acquisition Methods, Sarah Joy

Dissertations & Theses (Open Access)

Four-dimensional computed tomography (4D CT) has increased the accuracy of radiation treatment planning for patients in whom the extent of target motion is large. 4D CT has become a standard of care for radiation treatment simulation, allowing decreased motion artifacts and increased spatiotemporal localization of anatomical structures that move. However, motion artifacts may still remain. These artifacts, or artificial anatomic spatial distributions, add a systematic uncertainty to the treatment process and limit the accuracy of lung function images derived from CT. We proposed to reduce the motion artifacts in cine 4D CT by using three novel investigational 4D CT acquisition …

Forecasting Longitudinal Changes In Oropharyngeal Tumor Volume, Position, And Morphology During Image-Guided Radiation Therapy, Adam D. Yock

Dissertations & Theses (Open Access)

The purpose of this work was to generate, evaluate, and compare models that predict longitudinal changes in oropharyngeal tumor volume, position, and morphology during radiation therapy.

One volume, one position, and two morphology (size, shape, and position) feature vectors were used to describe 35 oropharyngeal gross tumor volumes (GTVs) during radiation therapy. The two morphology feature vectors comprised the coordinates of the GTV centroids and one of two shape descriptors. One shape descriptor was based on radial distances between the GTV centroid and 614 surface landmarks. The other was based on a spherical harmonic decomposition of these distances. For a …

Use Of Positron Emission Tomography For Proton Therapy Verification, Jongmin Cho

Dissertations & Theses (Open Access)

Positron emission tomography (PET), a tool commonly used for cancer staging and response monitoring, has recently been used for proton therapy verification. By imaging tissue activation following proton treatment, attempts have been made to verify proton dose and range. In this dissertation, two novel approaches were developed and tested for the purpose of help improve the proton dose and range estimation as well as verification.

Although there are still some challenges, attempts for proton dose verification using PET has been made by comparing Monte Carlo dose and PET simulations with treatment planned dose and measured PET. In this approach, …

Performance Evaluation Of Material Decomposition Using Rapid Kvp-Switching Dual-Energy Ct For Assessing Bone Mineral Density, John M. Wait

Dissertations & Theses (Open Access)

Osteoporosis is diagnosed by assessing the bone mineral density (BMD) of the trabecular bone, and has previously been characterized with dual-energy x-ray absorptiometry (DXA) or single-energy computed tomography (SECT). Dual-energy computed tomography (DECT) is able to create two three-dimensional sets of images representing the densities of two materials in a given basis pair. DECT is theoretically capable of providing a true density measurement of trabecular bone material with the proper material basis pair.

Using the rapid kVp-switching GE HD750 scanner, the concentrations of various solutes were assessed in two-material syringe-phantoms in different experimental conditions with DECT material density images, SECT …