Abstract: An X-ray examination apparatus includes an exposure control circuit (20) which supplies a control signal for adjustment of the X-ray source (1). The exposure control circuit (20) determines the control signal from an area of the X-ray image in which no overexposure occurs. To this end, the exposure control circuit includes a selection unit (23) for determining a measuring part from an electronic image signal, formed from the X-ray image by means of an X-ray detector (5, 8, 7), by comparing the signal level of the electronic image signal with an upper limit value which is dependent on the setting of the X-ray apparatus, for example of the high voltage and the anode current of the X-ray source. The upper limit value preferably amounts to the difference between the overexposure level and a safety margin. The safety margin serves to render the exposure control circuit insensitive to small fluctuations of the intensity and energy of the X-ray beam (3) generated by the X-ray source (1).

Abstract: An image sensing device is provided with an image sensor having one or more radiation-sensitive elements which convert incident radiation into collected charges. A read-out circuit converts the collected charges into pixel signals which contain a hold level and an image level, the hold level providing a comparison voltage and the image level being representative of a charge quantity. The hold level is formed by coupling the read-out circuit temporarily to a comparison voltage; this coupling is done by closing a transistor which adds thermal noise to the pixel signal. The image sensing device comprises a signal processing circuit which comprises a clamp circuit which makes hold-levels of different pixel signals substantially equal. The image level of each pixel signal is offset by the same amount as its hold level. An electronic image signal is formed as a result of integration of the image level in respect of the clamped hold level.