a contrast medium injector for injecting a patient with contrast medium for a ct scan is programmed to provide an injection protocol that is a representation of an ideally defined exponential curve with an initial injection rate decaying at an exponential rate . this has been found to produce a uniform vascular enhancement for the scanning of a patient &# 39 ; s blood vessels . the particular exponential decay coefficient which has been found to be optimal is directly proportional to the cardiac output divided by the patient &# 39 ; s weight and is approximated at 0 . 01 for a typical human .