An X-ray computed tomography (CT) method of producing sectional images and panoramic images while reducing the exposure dose and time. The method includes producing an X-ray projection image on a two-demensional X-ray image sensor by turning a rotary arm within a scope of angle according to the projection conditions, while locally radiating conical X-ray beams, with a small width in the rotating direction of the beams, with the rotating center of the rotary arm fixed at the center position of the region to be X-rayed and the X-ray projection images are processed using specific equation as previously prepared by a computer to extract image information, and thereby to produce a sectional image of the local region of the object to be examined.
