A method and an apparatus are disclosed for patient-dependent optimization and reduction of the contrast medium amount. An embodiment includes provisioning patient-specific data, containing information about a patient cross-section relevant for the imaging measurement; establishing CT values and/or CNR values of a contrast medium to be expected for at least one region of interest of the patient for different candidate settings of x-ray source arrangement and/or of an image reconstruction device; determining a relevant candidate contrast medium amount for the different candidate settings, which would lead to a CT value or CNR value of the contrast medium which corresponds to the CT value or CNR value of the contrast medium at the reference setting of the x-ray source arrangement and/or image reconstruction device; and displaying an optimum relative candidate contrast medium amount and of the associated candidate setting.