Prospective ECG-triggered sequential scanning

• Cardiac CT applications require the synchronization of data acquisition to the cardiac cycle, i.e. to the movement of the heart. 
• For sequential imaging, a prospective trigger is derived from the ECG-trace to initiate the CT-scan with a certain delay time after the R-wave.
• The true delay time is calculated from a given phase parameter (e.g. a percentage of the RR-interval time) for each cardiac cycle individually based on a prospective estimation of the RR-intervals. 
• Usually, the delay is defined such that the scans are acquired during the diastolic phase of the heart.