Using modern diffusion weighted magnetic resonance imaging protocols, the orientations of multiple neuronal fiber tracts within each voxel can be estimated. Further analysis of these populations, including application of fiber tracking and tract segmentation methods, is often hindered by lack of spatial smoothness of the estimated orientations. For example, a single noisy voxel can cause a fibe...

Each of three cone beam computed tomography (CBCT) machines offer a small field of view (FOV); Promax, Accuitomo 3D, and Kodak 9000. The objectives were to determine, when using a small FOV, the difference in contrast-to-noise ratios (CNR) of images obtained from different machines and different scan settings within each machine. A phantom made of a dry mandible with an epoxy resin based substi...

Many medical images suffer from the partial volume effect where a boundary between two structures of interest falls in the midst of a voxel giving a signal value that is a mixture of the two. We propose a method to restore the ideal boundary by splitting a voxel into subvoxels and reapportioning the signal into the subvoxels. Each voxel is divided by nearest neighbor interpolation. The gray lev...

PURPOSE A comprehensive image-based characterization of white matter should include the ability to quantify myelin and axonal attributes irrespective of the complexity of fibre organization within the voxel. While progress has been made with diffusion MRI-based approaches to measure axonal morphology, to date available myelin metrics simply assign a single scalar value to the voxel, reflecting ...

This study investigated radiation dose variations in pre-clinical irradiation due to the photon beam energy and presence of tissue heterogeneity. Based on the same mouse computed tomography image dataset, three phantoms namely, heterogeneous, homogeneous and bone homogeneous were used. These phantoms were generated by overriding the relative electron density of no voxel (heterogeneous), all vox...

OBJECTIVE Intracranial stenting for stent-assisted coiling of aneurysms requires adequate follow-up imaging. The aim of this in vitro study was to compare in-stent artificial luminal narrowing on contrast-enhanced MR angiograms (CE-MRA) when applying Neuroform® and Enterprise® stents for stent-assisted coiling. MATERIALS AND METHODS Two intracranial nitinol stents (Enterprise® and Neuroform®)...

Introduction A number of acquisition and reconstruction techniques have recently been proposed to extract the orientations of the white matter fibres within each imaging voxel from diffusion-weighted imaging (DWI) data. Of these, the diffusion tensor model is currently the most commonly used, but is limited in that it cannot resolve crossing fibres [1]. Constrained spherical deconvolution (CSD)...

The aim of this work was to calculate synthetic digital chest tomosynthesis projections using a computer simulation model based on the Monte Carlo method. An anthropomorphic chest phantom was scanned in a computed tomography scanner, segmented and included in the computer model to allow for simulation of realistic high-resolution X-ray images. The input parameters to the model were adapted to c...

TOWARD MAGNETIC RESONANCE ONLY TREATMENT PLANNING: DISTORTIONMITIGATION AND IMAGE-GUIDED RADIATION THERAPY VALIDATIONbyRYAN GLEN PRICEAugust 2016Advisor: Dr. Carri K. Glide-Hurst Major: Medical PhysicsDegree: Doctor of PhilosophyWhile MR-only treatment planning has shown promise, there are still severalwell-known challenges that are currently limiting widespread ...

Simulated magnetic resonance imaging brain studies have been generated for over a decade. Despite their useful potential, simulated cardiac studies are only emerging. This article focuses on the realistic simulation of cardiac magnetic resonance imaging datasets. The methodology is based on the XCAT phantom, which is modified to increase realism of the simulated images. Modifications include th...