Flat panel detector-based cone beam CT : reconstruction implementation and applications for dynamic imaging

Thesis (Ph. D.)--University of Rochester. Dept. of Electrical and Computer Engineering, 2008.X-ray Computed Tomography has experienced several generations of development from single detector cell, several detector cells, an array of detector cells, through multiple rows of detector cells and two-dimensional detector cells. The introduction of the area detector is one of the key characteristics of the cone beam CT which represents a breakthrough in terms of the real three-dimensional isotropic resolution, large Z-coverage. Dedicated object scanning such as breast cone beam CT and dentomaxillofacial cone beam CT are made possible. The area detector which is large enough to cover the entire organs, such as the heart, the kidneys, the brain, or a substantial part of a lung, in one axial scan could bring a new quality to medical CT. With these new systems, real dynamic volume scanning would become possible, and a whole spectrum of new applications, such as functional or volume perfusion studies, could arise. Challenges also come with the excitement of cone beam CT, such as beam hardening, scattering, non-uniform distribution over the area detector, and gain non-linearity at each detector cell, and cone angle induced reconstruction artifacts if only a circular scan is employed. In this thesis, a heuristically weighted function was developed for the cone beam half scan circular scanning scheme so as to improve the temporal resolution and suppress the motion artifacts; a composite hybrid scanning scheme was proposed to correct the cone angle-induced artifacts for the cone beam breast imaging CT prototype. A dynamic experimental phantom and an animal (mouse) study was conducted to develop a dynamic scanning protocol to testify the feasibility of the angiogenesis (i.e. to differentiate the benign and malignant tumor by depicting the dynamic uptake of the contrast agent in vasculature) imaging associated with the cone beam breast imaging CT