Exposure control in an x-ray image detector

摘要

An x-ray detector apparatus comprises an array of detector pixels (20), each pixel (20) comprising a conversion element (26, 260) for converting incident radiation into a charge flow, a charge storage element (28) and a switching device (29) enabling the charge stored to be provided to an output of the pixel (20). A plurality of dose sensing pixels further comprise a dose sensing element (40, 50) during x-ray exposure results in a change in the charge stored on the charge storage element (28) and also results in a dose sensing signal being generated which can be read out from the pixel (20). The dose sensing pixels enable a dose signal to be obtained without reading the charges stored on the pixel charge storage elements, so that dose sensing can be carried out during exposure.