X-ray luminescence computed tomography (XLCT) is an emerging hybrid modality in which X-ray excitable particles (phosphor particles) emit optical photons when stimulated with X-ray photons. Optical imaging has high measurement sensitivity but it has limited spatial resolution for deep targets due to high scattering of optical photons. X-ray imaging has high spatial resolution yet its sensitivity is limited. XLCT can potentially combine the high spatial resolution of x-ray imaging with the high sensitivity of optical imaging. In this project, a prototype XLCT imaging system is built, in which a collimated x-ray beam is used to excite x-ray excitable particles. Ultrafine x-ray beams with beam size of about 200 micrometers are used to improve the spatial resolution of XLCT. Numerical simulations and phantom experiments are used to validate the XLCT imaging system. This thesis is outlined as follows:

Chapter 1 presents the overview of XLCT; Chapter 2 presents XLCT system buildup; Chapter 3 describes XLCT reconstruction algorithm and numerical simulation; Chapter 4 reports XLCT phantom experimental results; finally Chapter 5 summarizes the thesis with ideas for future research on XLCT.