Abstract: In an X-ray CT (computerized tomographic) imaging method, scano data is produced from X-ray projection image data about a helically-scanned biological body under medical examination. The X-ray projection image data are acquired only at a predetermined projection angle such as 0.degree. during a helical scanning operation. Accordingly, no X-ray projection to acquire the scano data is required to reduce X-ray dose given to the biological body.

Abstract: A system for data transfer includes a plurality of disks each having surfaces divided into sectors in which data may be stored; drive mechanisms for rotating the disks; a plurality of data transfer heads, one transfer head associated with each disk surface; sector determining circuitry for determining the current sector of each disk surface relative the associated head; and control circuitry responsive to the sector determining circuitry, for initiating transfer of data between the head and the associated disk surface whenever the head for that surface is at the beginning of any sector involved in the data transfer. The system further includes a memory; and a data bus coupled to the memory; a buffer coupled between each of the heads and the data bus.

Abstract: An apparatus for detecting and correcting errors which occur when transferring data between a magnetic disk and the main memory of a magnetic disk system. Error detection apparatus determines the corrections of sectors of data as the sectors are transferred from a magnetic disk to main memory. A main controller is notified by the error detection apparatus as to which sectors of data have been transferred incorrectly, and are therefore in need of correction. At the request of the main controller, the sectors in need of correction, i.e., the sectors in error, are transferred from main memory to the main controller which has error correction apparatus. The main controller corrects the sectors in error and then returns the sectors in error to main memory. The main controller receives sectors in error from main memory, and transfers corrected sectors of data back to main memory only during free times when data is not being transferred between the main memory and a magnetic disk.