METHOD FOR THE AUTOMATIC CENTERING OF AN OBJECT TO BE EXAMINED BY A TOMODENSITOMETER USING A FAN-SHAPED BEAM, AND TOMODENSITOMETER ADAPTED FOR THIS METHOD

摘要

A tomodensitometric apparatus for the radiological examination of an object by relative rotation with respect to said object of a fixed array consisting of a source of penetrating radiation and a plurality of detectors disposed along a line. In order to correctly position the object in the center of the radiation field prior to the examination and without subjecting the object to a dose of test radiation, the invention provides a movable screen which is placed between the source and the object to be examined. The dimensions of the screen are such as to prevent the radiation emanating from the source from reaching any but at least one of the two outermost-lying detectors in the line of detectors. When the array is rotated in a test cycle, the signals from the one or two outermost detectors are received by a suitably programmed computer which generates a displacement schedule that is transmitted to the controller and displaces the object in the direction necessary to move it to the center of the radiation field.