The Transportation Security Administration (TSA) does not monitor the Advanced Imaging Technology (AIT) to ensure it continues to fulfill needed capabilities. Although the AIT met the requirement for system availability, TSA did not monitor the AIT’s probability of detection rate and throughput rate requirements set forth in TSA’s operational requirements document. These issues occurred because TSA has not established comprehensive guidance to monitor performance of the AIT system. Without continuous monitoring and oversight, TSA cannot ensure the AIT is meeting critical system performance requirements—a consistent weakness found in prior DHS OIG reports. We made two recommendations designed to improve TSA’s monitoring of the AIT system. TSA concurred with our recommendations.