Screening people for illicit substances: a survey of current portal technology.

The need to implement more effective, cost efficient, non-intrusive ways of screening people for concealed drugs, explosives and weapons is a major security initiative for the U.S. and elsewhere. A new generation of portals suitable for security checkpoints is under development. These will be able to find contraband with high probabilities of detection, and low false-alarm rates. Some portals image the body using either low dose X-rays or millimeter wave interrogation, and analyze the radiation back-scattered from the body, providing images of concealed objects. Other portals operate essentially as anomaly detectors, finding objects on the human body. A series of portals is also under development that can harvest and analyze vapors or particles of the contraband substances. Some of the issues surrounding portal development include perceived safety issues, privacy issues, and operational issues such as ease of operation, non-invasiveness, and ease of interpretation. It is believed that portal technology will mature, and the cost of portals will fall sufficiently to make widespread deployment of portals at security checkpoints a reality within the next decade.