Disclosed is a rotating-grating cone beam CT imaging apparatus. This imaging apparatus is composed of a frame, a frame angle sensor, an X-ray source equipped with a rotating grating, a flat panel detector, a main controller and an image reconstruction workstation. Like a general cone beam CT imaging apparatus, this imaging apparatus also adopts an open structure. But unlike the general cone beam CT imaging apparatus, the rotating grating limits X-rays emitted from the X-ray source to a plurality of narrow-angle cone beams or sector beams. In the process that the X-ray source and the detector rotate around an imaging object, projection images of the narrow-angle cone beams or sector beams on the flat panel detector move back and forth continually through the rotation of the rotating grating, so as to acquire projection information about the imaging object in an entire scanning region. Finally, the projection information is reconstructed into a volume image in the image reconstruction workstation. In this manner of variable-focus scanning, the present invention not only can reserve the advantage of the open structure of the cone beam CT imaging apparatus, but also obtains the advantage that a sector beam CT imaging apparatus can restrain scattered photons so as to generate a high-quality image.
