| 摘要 |
A method and device to calibrate an automatic exposure control (AEC) device in an x-ray imaging system is disclosed. An x-ray imaging system has an x-ray generator and tube to generate x-rays, an AEC device to control exposure of the x-rays, and an image sensing system, such as a film/screen combination or a digital recording system, which convert the x-rays into a converted medium, such as light, which can be easily sensed by a sensing medium. To calibrate the AEC device, a detector is placed in the position of the sensing medium to detect the converted medium. The detector detects signals indicative of the x-rays on a sensing medium. Simultaneously, a signal is obtained from the AEC. When the signal from the detector corresponds to a predetermined desired detector output, the output signal from the AEC is stored. The stored AEC output value corresponds to the target AEC output which will produce a proper exposure in the future for the same set of predetermined conditions of the imaging system. The process is repeated for different sets of predetermined conditions until all of the desired sets of predetermined conditions have been calibrated. There is a preliminary step to determine the desired detector output. This preliminary step comprises fixing an attenuation filter about the sensing means, which has graded attenuations, and placing these in the imaging system along with a detector. The x-ray generator then generates x-rays and the desired detector output is determined by comparing the attenuation caused by the attenuation filter with detected signal.
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