This course provides attendees with basic working knowledge of the fundamentals of exact image reconstruction in cone beam CT. The course starts with the general theory, then we discuss various approaches to obtaining inversion formulae, and then we consider specific trajectories, such as helical and circle plus a curve. We include a discussion of implementation techniques, analysis of detector requirements and data usage. We will also discuss image quality of exact Katsevich-type (shift-invariant filtered-backprojection structure) reconstruction. Course outline: • Foundations of three-dimensional image reconstruction theory in computed tomography - Radon transform, cone beam transform, Grangeat's formula • General reconstruction scheme - intersections of the source trajectory with Radon planes, weight function n, inversion of the cone beam transform • Approaches to obtaining reconstruction formulae, including the Zou-Pan approach - Reconstruction on chords; Gelfand-Graev formula; Pack-Noo approach - Reconstruction on M-lines; and other approaches • Trajectory-specific choice of the weight function for optimal reconstruction performance, both helical (1-PI, 3-PI, and Fractional-PI) and generalized circle-plus trajectories (open circle + line, and closed circle + curve) • Implementation details including filtering lines rebinning and detector requirements • Image quality