Medical Biophysics Commons^™

Analyzer-Less X-Ray Interferometry With Super-Resolution Methods, Murtuza S. Taqi

LSU Master's Theses

X-ray interferometry provides valuable information on attenuation, small-angle scattering, and differential phase contrast. This multi-modal contrast can aid in many clinical applications, such as lung diseases and breast cancer. However, standard inter- ferometry has an analyzer grating that can increase the dose requirement to maintain the same image quality as a standard X-ray. We propose the use of super-resolution methods for X-ray grating interferometry without an analyzer, with detectors that fail to meet the Nyquist sampling rate needed for traditional image recovery algorithms. Detector phase- steps are used to nominally recover the sampling and iteratively recover the visibility and the …

Dose Characterization Of Galactic Cosmic Rays In The Human Brain: A Phits-Based Study With A Segmented Anatomical Phantom, Shanice N. Manning

LSU Master's Theses

Astronauts aboard the International Space Station (ISS) are chronically exposed to a complex space radiation environment composed of galactic cosmic rays (GCR), solar particles, and Earth's trapped radiation. These high-energy particles interact with spacecraft shielding, producing secondary particles that can penetrate inside and deposit energy in sensitive tissues. Although animal studies have been useful in assessing space radiation risks, anatomical and physiological differences limit their applicability to human anatomy especially neuroanatomy. To address this gap, we developed a computational framework to model radiation dose distribution within the human brain using Monte Carlo simulations in Particle and Heavy Ion Transport code …

Scintillation Event Localization In Novel Hemi-Ellipsoid Detector For Spect, Hanif R. Soysal

LSU Master's Theses

A high sensitivity Cardiac SPECT system using hemi-ellipsoid crystals with pinhole collimation was previously proposed by Dey et al. To investigate detector resolution for this design, the scintillation light spread on a monolithic hemi-ellipsoidal CsI crystal was simulated using Geant4 Monte Carlo. The expected distribution of scintillation light on the outer surface of the crystal from photoelectric absorption events was obtained from the simulations for selected points inside the crystal. Two sets of simulations were performed. For the first set, a look-up table (LUT) of 12 points was created and each point mapped to its expected light distribution—four points at …

Evaluation Of Ventilation Assistance For Improving Respiratory Reproducibility In Radiation Therapy, Cameron J. Sprowls

LSU Master's Theses

Background: Respiratory motion affects all tumor sites in the thorax and abdomen. Variations of the respiratory pattern cause variations of the tumor motion which can result in differences between the planned and delivered dose distributions. Previous breathing guidance techniques have been investigated to improve respiratory reproducibility; however, ventilation assistance has not been investigated. We evaluated using bi-level positive airway pressure (BIPAP) ventilation assistance for improving respiratory reproducibility in patients with tumor sites impacted by respiratory motion.

Methods: Written informed consent was obtained for 10 patients currently undergoing radiation therapy treatment. Patients participated in sessions over their course of treatment, which …