During coronary artery angiography, catheter is used to inject a contrast dye into the coronary arteries. Due to the anatomical variation of the aorta and the coronary arteries in different humans, one common catheter cannot be used for all patients. The cardiologists test different catheters for a patient and select the best catheter according to the patient's anatomy. The focus of this work is to overcome these problems by proposing a computer-aided catheter selection procedure. This thesis work is best for coronary arteries with high take off. It involves segmentation of the aorta and coronary arteries, finding the centerline and computing some geometric parameters. Then after comparing these calculated parameters it suggests a catheter that is the closest to the patient’s arteries geometry. This solution avoids testing of many catheters. The cardiologist already gets a recommendation about the optimal catheter for the patient.