Your father was probably having a cardiac angiogram. A cardiac angiogram is more invasive. A catheter is inserted into an artery in an arm or leg and contrast dye is injected through the catheter. Xray fluoroscopy is used to monitor. They can perform an angioplasty during the procedure. A CT angiogram is contrast dye injected into a vein and a CT scanner takes the images. Less invasive. No recovery time.