The compact and easy to use phantom designed to invoke a response of automatic-exposure. Follows the Center for Devices and Radiological Health (CDRH) specifications of a chest phantom and AAPM recommendations from Report No. 31 ”Standardized Methods for Measuring Diagnostic X-Ray Exposure”. The adult chest phantom approximates a 173 cmadult weighing approximately 165 lbs with an anterior-posterior (AP) thickness of about 23 cm. The anatomical region the phantom simulates is the lung field, and therefore contains an air gap within the center. The phantom is composed of polymethyl-methacrylate (PMMA).