Abstract: This paper summarizes the recent contributions made by the authors in the field of CT imaging. The work includes both theoretical research and industrial applications of methods about image reconstruction, image processing and understanding. The contributions can be concluded into four aspects: i) algorithms for 3D cone-beam reconstruction are analyzed in performance and with error distribution, and a new algorithm is proposed to improve image quality; ii) reconstruction methods under different principle are studied and implemented, iii) system performance is evaluated theoretically and experimentally based on task, iv) effective methods for image processing and understanding are presented and verified for practical usage.