Search by X-rays applied technology

X-rays and gamma-rays are part of different methods of imaging for control purpose. The main and most widely used method is conventional fluoroscopy with transmission images. Dual energy imaging, backscatter imaging and computed tomography allow visualizing of interesting items or of single layers without superposition; these methods have been developed recently or have been adapted to imaging for security reasons. Dual energy uses the specific absorption characteristics of a substance. Spectroscopy permits the identification of substances in packages or luggage, without direct access. Industry offers technical solutions which combine different methods. Comparing the different methods, one has to conclude that the disadvantage of the transmission image is due to superimposition, which limits the recognition of searched items. The combination with other methods increases the reliability of recognition. Future will bring more controls for security reasons and in consequence, more “control imaging” by X-rays. Imaging for security reasons will be combined with pattern recognition; politicians will answer the demand for security and impose more controls.