This paper presents the first performance evaluation of a dual-source computed tomography (DSCT) system, which features two X-ray tubes and detectors mounted on a rotating gantry with a 90° angular offset. The authors introduce the system concept and discuss its potential benefits for echocardiograph (ECG)-controlled cardiac CT and general radiology applications. They evaluate both temporal and spatial resolution using phantom scans and present initial patient scans to illustrate the system's performance in ECG-gated cardiac imaging. The DSCT system achieves 83 ms temporal resolution for coronary CT angiography (CTA) and basic functional parameter evaluation, and 60 ms (minimum 42 ms) for advanced functional evaluation with dual-segment reconstruction. The z-flying focal spot technique allows resolving 0.4 mm cylinders at all heart rates, enhancing robustness for patients with high heart rates. The dual-energy acquisition mode demonstrates the automatic separation of bones and iodine-filled vessels. The introduction reviews the current status of ECG-gated cardiac CT, highlighting improvements from four-slice to 16-slice and 64-slice CT systems, and discusses the challenges and limitations of motion artifacts, spatial resolution, and breath-hold times. The paper concludes by emphasizing the potential for further improvements in temporal resolution to eliminate the need for heart-rate control.This paper presents the first performance evaluation of a dual-source computed tomography (DSCT) system, which features two X-ray tubes and detectors mounted on a rotating gantry with a 90° angular offset. The authors introduce the system concept and discuss its potential benefits for echocardiograph (ECG)-controlled cardiac CT and general radiology applications. They evaluate both temporal and spatial resolution using phantom scans and present initial patient scans to illustrate the system's performance in ECG-gated cardiac imaging. The DSCT system achieves 83 ms temporal resolution for coronary CT angiography (CTA) and basic functional parameter evaluation, and 60 ms (minimum 42 ms) for advanced functional evaluation with dual-segment reconstruction. The z-flying focal spot technique allows resolving 0.4 mm cylinders at all heart rates, enhancing robustness for patients with high heart rates. The dual-energy acquisition mode demonstrates the automatic separation of bones and iodine-filled vessels. The introduction reviews the current status of ECG-gated cardiac CT, highlighting improvements from four-slice to 16-slice and 64-slice CT systems, and discusses the challenges and limitations of motion artifacts, spatial resolution, and breath-hold times. The paper concludes by emphasizing the potential for further improvements in temporal resolution to eliminate the need for heart-rate control.