Engineering Commons^™

Three-Dimensional Image Reconstruction In Transcranial Photoacoustic Computed Tomography, Joemini Poudel

McKelvey School of Engineering Theses & Dissertations

Photoacoustic computed tomography (PACT) is an emerging imaging modality that exploitsoptical contrast and ultrasonic detection principles to form images of the photoacousticallyinduced initial pressure distribution within tissue. The PACT reconstruction problemcorresponds to an inverse source problem in which the initial pressure distribution is recoveredfrom measurements of the radiated pressure wavefield. A major challenge in transcranialPACT brain imaging is compensation for aberrations in the measured data due to the presenceof the skull. Ultrasonic waves undergo absorption, scattering and longitudinal-to-shear wavemode conversion as they propagate through the skull. To properly account for these effects, awave-equation-based inversion method should be employed that can …

Joint Reconstruction For Single-Shot Edge Illumination Phase-Contrast Tomography (Eixpct), Yujia Chen

McKelvey School of Engineering Theses & Dissertations

Edge illumination X-ray phase-contrast tomography (EIXPCT) is an emerging X-ray phasecontrast tomography technique for estimating the complex-valued X-ray refractive index distribution of an object with laboratory-based X-ray sources. Conventional image reconstruction approaches for EIXPCT require multiple images to be acquired at each tomographic view angle. This contributes to prolonged data-acquisition times and elevated radiation doses, which can hinder in vivo applications. In this dissertation, a new “single-shot” method without restrictive assumptions related to the object, imaging geometry or hardware is proposed for joint reconstruction (JR) of the real and imaginary-valued components of the refractive index distribution from a tomographic data …

Quantitative Hyperspectral Imaging Pipeline To Recover Surface Images From Crism Radiance Data, Linyun He

McKelvey School of Engineering Theses & Dissertations

Hyperspectral data are important for remote applications such as mineralogy, geology, agriculture and surveillance sensing. A general pipeline converting measured hyperspectral radiance to the surface reflectance image can provide planetary scientists with clean, robust and repeatable products to work on.

In this dissertation, the surface single scattering albedos (SSAs), the ratios of scattering eciency to scattering plus absorption eciences of a single particle, are selected to describe the reflectance. Moreover, the IOF, the ratio of measured spectral radiance (in the unit of watts per squared-meter and micrometer) to the solar spectral radiance (in the unit of watts per squared-meter and …