Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 5 of 5
Full-Text Articles in Medicine and Health Sciences
An Algorithm To Improve Deformable Image Registration Accuracy In Challenging Cases Of Locally-Advanced Non-Small Cell Lung Cancer, Christopher L. Guy
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 …
Treatment-Induced Breast Cancer Dormancy And Relapse, Rebecca Keim
Treatment-Induced Breast Cancer Dormancy And Relapse, Rebecca Keim
Theses and Dissertations
When breast tumor cells encounter stress due to cancer therapies, they may enter a dormant state, escaping from treatment-induced apoptosis. Dormant cells may eventually regain proliferative capabilities and cause recurrent metastatic disease, which is the leading cause of mortality in breast cancer patients. We sought to determine if a high dose of radiation therapy (RT) or combined chemo-immunotherapy, with and without the blockade of autophagy by chloroquine (CQ), could overcome treatment-induced tumor dormancy or relapse. We found that autophagy contributes in part to treatment-induced tumor dormancy. We also found that three therapeutic strategies were successful in inhibiting or preventing tumor …
Statistical Modeling Of Interfractional Tissue Deformation And Its Application In Radiation Therapy Planning, Douglas J. Vile
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 …
Adaptive Radiation Therapy For Lung Cancer, Christian W. Dial
Adaptive Radiation Therapy For Lung Cancer, Christian W. Dial
Theses and Dissertations
Prognosis for lung cancer patients remains poor. For those receiving radiation therapy, local control and survival have been shown to improve with increased doses; however, deliverable dose is often limited by associated toxicity. Therefore, methods that reduce dose to normal tissues and allow isotoxic escalation are desirable. Adaptive radiation therapy seeks to improve treatment by modifying the initial plan throughout delivery, and has been shown to decrease normal tissue dose. Studies to date suggest a trend of increasing benefit with increases in replanning frequency; however, replanning is costly in terms of workload and past studies implement at most weekly adaptation. …
A Quantitative Method For Reproducible Ionization Chamber Alignment To A Water Surface For External Beam Radiation Therapy Depth Dose Measurements, James Ververs
Theses and Dissertations
Ionization chambers (ICs) are the most commonly used detectors for radiation therapy dose measurements. Typical IC measurements use cylindrical ICs in a water phantom and therefore require initial IC alignment to the water surface. This alignment has long been ignored and only recently has a qualitative governing recommendation been made. This thesis describes a reproducible methodology for quantitative ionization chamber water surface alignment. Depth-ionization measurements are taken with twenty-eight IC designs under varying conditions including, but not limited to, changes in scan direction, speed, and resolution, radiation beam type, field size, energy, and electron contamination. Measurements are acquired using standard …