Used primarily as a radiocontrast agent in diagnostic imaging, especially for visualizing the gallbladder and biliary system. Administered orally, it enhances X-ray images by absorbing radiation, allowing clear differentiation of soft tissues and ducts. Its use helps detect gallstones, tumors, and structural abnormalities in the liver and bile passages. Also employed in cholecystography, where it concentrates in the gallbladder after absorption from the gastrointestinal tract. Though largely replaced by newer agents and imaging techniques, it remains an option in specific oral contrast procedures.