A method is disclosed for providing tomographic pictures of a patient with the aid of a tomographic system by using contrast medium injections. The patient is firstly injected with a defined test bolus, while the temporal concentration profile of the contrast medium in at least one body region is determined in at least one scanning plane. The functional parameters of a prediction model that maps or at least approximates the relationship between the profile of a contrast medium injection and the temporal profile of the contrast medium concentration in the body region are determined from the measured profile of the contrast medium concentration in relation to the profile of the test bolus injection. After the specification of a desired contrast in the body region, the profile of a contrast medium injection that is required therefore is automatically calculated in temporal relationship with the scan, and the start of the tomographic scan and the start of the contrast medium injection and the profile thereof are started automatically in a fashion temporally tuned to one another.