10% of American population might have gallstones, and we do diagnose one million gallstone patients each year. Among the million, we do over half a million cholecystectomies in the United States. Actually, at any given time 20 million Americans might have gallstones. Among these patients around 80% have gallstones that are cholesterol in nature. This is important for our topic because for biliary lithotripsy we're going to select patients with cholesterol gallstones. And our selection criteria according to the FDA is a little bit restricted. We will follow the guidelines: single stone, 5 millimeters to 20 millimeters single stone, functioning gallbladder. In United States, in the world, gold standard for the gallstone treatment is the lap. cholecystectomy.