| 摘要 |
An X-ray examination apparatus includes an X-ray source (1) for emitting an X-ray beam, an X-ray detector (6) for detecting an X-ray image and converting it into an optical image, and a video extractor (8) which is coupled to the X-ray detector (6) via optical coupling means (9). The optical coupling means (9) is provided with an optical pick up (11) for feeding a fraction of the light flux to a photosensor (12) which produces a control signal for adjusting the X-ray flux from the X-ray source (1). The photosensor (6) is provided with an array of pixels, with weighting means for the signals detected in or by each of said pixels, and with means for determining a mean value of the detected and weighted signals, yielding a control signal which is fed back in order to adjust the X-ray flux from the X-ray source (1).
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