Patent ID: 7995703
Filing Date: 2011-08-09
Classification: A61B

Abstract:
1. A method for controlling automatic X-ray exposure in an X-ray CT system, said method comprising: establishing one of a correspondence table and a function relationship between a ratio factor r and an offset Cy of a geometrical center of a scanned section, wherein the ratio factor r represents a ratio of a projection area value when the geometrical center of the scanned section of a subject deviates from a rotation center to a standard projection area value when the geometrical center of the scanned section of the subject is located at the rotation center; scout scanning the subject and calculating a “measured projection area value” and a Projection Measure based on data obtained in the scout scan; calculating the offset Cy of the geometrical center of the scanned section from the rotation center by: substituting the offset Cy into one of the correspondence table and function relationship to obtain its corresponding ratio factor r; calculating the standard projection area value based on the ratio factor r and the measured projection area value; and automatically determining by automatic exposure function a tube current value required for exposure based on the calculated standard projection area value, the Projection Measure, and carrying out exposure.