Threat Localization in QR Explosive Detection Systems

The detection of explosives for the purpose of aviation security is an important task for preventing terrorism acts and smuggling. A number of methods for explosive screening have been developed. For the purpose of aviation security, the inspections are performed on passengers, their carry-on luggage, checked baggage, and cargo containers. An effective explosive detection system should be capable of reporting the type of energetic material, the mass, the object shape and its location within the volume being scanned. Quadrupole resonance (QR) is a mature technique for detecting and classifying explosives concealed in unopened containers. We report recent research on threat localization techniques, aimed to enhance the efficiency of QR-based baggage scanner systems. The methods investigated for threat localization are based on the effect of inhomogeneous static magnetic fields, nonuniform radio-frequency excitation, and the use of spatially selective radio-frequency coils for one- and two-dimensional mapping.