The present invention relates to collimation of X-ray radiation and comprises an X-ray source arrangement for medical imaging, the X-ray source arrangement comprising an X-ray source, and an X-ray beam shutter device. The X-ray source has at least at a first and a second focal spot position distanced apart from each other in a direction transverse to a main radiation direction. The X-ray beam shutter device comprises at least a first pair of shutters defining a first diaphragm, and at least a second pair of shutters defining a second diaphragm. The first pair of shutters is configured for alignment with a first line-of-sight between the first focal spot position and a center of a detector, and the second pair of shutters is configured for alignment with a second line-of-sight between the second focal spot position and a center of a detector. The first and the second diaphragm partly overlap.
