sentences:  In 1958, Interventional Radiologist, Dr. Charles Dotter began working on methods to visualize the coronary anatomy via sequential radiographic films.He invented a method known as occlusive aortography in an animal model.Occlusive aortography involved the transient occlusion of the aorta and subsequent injection of a small amount of radiographic contrast agent into the aortic root and subsequent serial x-rays to visualize the coronary arteries.