A method and system for using Threat Imaging Projection (TIP) technology, and the operator testing data that it generates, in order to certify x-ray inspection system operators and thereby assure an acceptable and uniform level of operator performance. In a preferred configuration, the operator views x-ray images of objects on a screening system equipped with TIP technology. When the operator believes that a threat item image appears on the screening system, the operator indicates such via an indicating means. The system is capable of recording, storing and transmitting individual operator performance data relating to proper detections, missed detections, and false alarms, i.e., when an operator indicates that a threat item image appears when no such image actually appears on the screening system. The system preferably contains a library of various threat item images, e.g., guns, bombs, knives, etc., which are classified according to type of threat and difficulty of detection.