Abstract: There provided is a radiation computed tomography (CT) scanner, such as an X-ray CT scaner. A CT image of an object is obtained, resolution of the CT image being affected by a resolution adjustment parameter and the object having an axis. In case of an X-ray CT scaner, the scanner comprises a couch having a longitudinal direction, the axis of the object being aligned along the longitudinal direction, an X-ray source for radiating X-rays toward the object, a detector for detecting the X-rays transmitted through the object, an element for rotating at least the X-ray source around the object, an element for at least relatively moving the X-rays in the longitudinal direction, and an element for controlling the resolution adjustment parameter. Slit members may further be provided for forming the X-rays into a given slice thickness.

Abstract: The x-ray absorption factor of each end section of a top table is lower than that of a middle section thereof. If the end section of the top table protrudes from an effective field of scan so that fan beams are transmitted through the protruded portion, the beams can hardly be absorbed by the protruded portion. Accordingly, projection data obtained are hardly subject to any significant differences which depend on the transmission of the fan beams. Even though an image is reconstructed in accordance with the obtained projection data, therefore, it can be restrained from suffering shading. Thus, a high-quality image can be obtained.

Abstract: First and second arms are supported, rotatable to each other and in the shape of X, by a shaft. The lower end of the first arm is on the side of a scan gantry and rotatably supported on a base by means of a rotation fulcrum. The lower end of the second arm and upper ends of the first and second arms are supported by base and frame rails through movement fulcrums to be rotatable in relation to and movable along the rails. A tension spring is stretched between the second arm and a mounting frame to urge the mounting frame toward the scan gantry. Stoppers are arranged in the frame rails to prevent the movement fulcrums of the first and second arms from moving from their predetermined positions in the direction of their separating from the scan gantry. The first arms are rotated and erected by a hydraulic cylinder.