1. A method for generating images in digital subtraction angiography with an X-ray diagnostic imaging system, comprising the following steps: accessing a mask image frame of a patient under examination; accessing a series of live image frames of the patient under examination acquired in the same imaging position of the mask frame acquisition, wherein one of the mask image frame and the live image frames is contrast-enhanced; assuming possible shift vectors in a region of interest and calculating a scoring thereof, each possible shift vector being a difference vector between the mask image frame and a respective live image frame, determining the possible shift vector with the highest scoring and choosing it as an elected shift vector, calculating a likelihood p representing a quality value of the elected shift vector, calculating a modified shift vector depending on the elected shift vector and the likelihood p, shifting the mask image frame with respect to the respective live image frame by the modified shift vector, subtracting the shifted mask image frame from the respective live image frame, and displaying the respective subtracted image frame.