(SFOV) The scan field of view is the area being scanned. This selectable scan factor is measured from a CT system isocenter to the most distant located edge of the patient.

See also Reconstruction Field Of View.

(RFOV) The reconstruction field of view is the size of the scan field of view (SFOV) that is reconstructed to form a CT image.

(Computed tomography number) The CT number is a selectable scan factor based on the Hounsfield scale. Each elemental region of the CT image (pixel) is expressed in terms of Hounsfield units (HU) corresponding to the x-ray attenuation (or tissue density).
CT numbers are displayed as gray-scale pixels on the viewing monitor. White represents pixels with higher CT numbers (bone). Varying shades of gray are assigned to intermediate CT numbers e.g., soft tissues, fluid and fat. Black represents regions with lower CT numbers like lungs and air-filled organs.

(DFOV / RFOV) The display field of view is a selectable scan factor measured from the center of the patient to the most distant located edge of the patient.

(FOV) The field of view is the maximum diameter of the area of the scanned object that is represented in the reconstructed image. It can also be the surface of the used detector.