1. A system for certifying security inspection system operators, comprising: an x-ray inspection machine for inspecting baggage items; a threat item image database including a plurality of certification images of which an operator must property detect a predetermined percentage to obtain a passing certification score; a monitor for displaying threat item images from the threat item image database, and for displaying x-ray images of baggage items; software for accessing the threat item image database to electronically produce a threat item image such that it appears on the monitor as if a threat item is located inside a baggage item; and an input device for allowing the operator to indicate when the operator believes that a threat item image appears on the monitor.