A photon-counting X-ray detector is for acquiring an X-ray image data set of an object penetrated by X-ray radiation. The detector includes a converter element, designed to convert incident X-ray radiation into an electrical signal; and a matrix with a plurality of pixel elements. At least a partial number of the plurality of pixel elements receive a signal input and at least one configurable counter is coupled to the at least a partial number of the plurality of pixel elements, for signaling. Further, the at least one configurable counter is designed to count either a pixel count signal, based on a signal directly received in each respective pixel element, or a coincidence count signal, based on the signal received directly in the respective pixel element and on a coincident signal of at least one further pixel element.