The invention relates to x-ray imaging technology as well as image post-processing. Particularly, the present invention relates to post-processing of perfusion image data acquired by an x-ray imaging apparatus by absolutely or relatively normalizing perfusion image data to allow a preferred comparison of the image data, both with regard to different acquisitions as well as different patients. To allow normalization of perfusion image data, it may be desirable to know the amount of contrast agent injected, which remains in a coronary. Subsequently, image parameters may be adapted or normalized based on the known amount of contrast agent within the coronary for normalization of perfusion image data. To obtain a precise amount of injected contrast agent, the injected volume of contrast agent flowing through a defined region or section of a vessel may be estimated. Said injected volume of contrast agent may thus be deduced from the estimation of the total volume flow at this location. Accordingly, a method (10) is provided for dynamic normalization of data for perfusion comparison and quantification, comprising the steps of determining (20) a total volume flow or an amount of a contrast agent in a blood vessel and normalizing (34) perfusion data based on the determined total volume flow or amount of contrast agent.