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Full-Text Articles in Medicine and Health Sciences

Epid-Based Dose Verification For Adaptive Radiotherapy, Joseph Gardner Nov 2012

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 …


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

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 …


Exploring The Social Determinants Of Sexually Transmitted Disease And High-Risk Sexual Behaviors, River Pugsley Apr 2012

Exploring The Social Determinants Of Sexually Transmitted Disease And High-Risk Sexual Behaviors, River Pugsley

Theses and Dissertations

Abstract 1: A multi-level assessment of disproportionate population sex ratios and high-risk sexual behaviors among STD clinic patients Low male-to-female sex ratios in a population may influence high-risk sexual behaviors, such as multiple sex partners and inconsistent condom use, which facilitate the transmission of STDs. This study used multi-level modeling to assess whether population sex ratios were associated with these two individual-level behaviors. All analyses were stratified by gender. Interview data were collected from patients (N = 9,203, 48% male) attending participating STD clinics. Interviews included information on socio-demographics and sexual behavior, including number of sex partners in the previous …