A medical imaging system adaptively acquires anatomical images using a shape adaptive collimator including multiple different portions of X-ray absorbent material automatically adjustable to alter the dimensions of a spatial cross section of an X-ray beam of radiation into a non-rectangular shape, in response to a control signal. The synchronization processor provides a heart rate related synchronization signal derived from a patient cardiac function related parameter. The synchronization signal enables adaptive variation in timing of image acquisition within an individual heart cycle and between successive heart cycles of each individual image frame of multiple sequential image frames. The X-ray image acquisition device uses the shape adaptive collimator for acquiring anatomical images of the region of interest with reduced patient X-ray exposure in response to the synchronization signal. A display processor presents resultant images.