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In this contribution, we present a dual high-energy X-ray imaging technique for cargo container inspection using the 'spectral high-energy X-ray attenuation method'. This method is based on attenuation of continuous highenergy spectra. The developed experimental technique consists of a betatron as high-energy (up to 7.5 MeV) X-ray source and a matrix detector with high spatial resolution (400 ìm) for digital X-ray imaging. In order to evaluate the material discrimination capability using dual high-energy X-ray imaging, a test specimen is proposed, comprising step wedges of different low and high atomic number (Z) materials. The selected X-ray spectra for the dual-energy experiments correspond to 3 MV and 7.5 MV acceleration potential of the betatron. We evaluated the ratio between low- and high-energy X-ray attenuation coefficients quantitatively based on simulated poly-energetic high-energy X-ray source spectra and the detector sensitivity using the 'analytical Radiographic Testing inspection simulation tool' (aRTist) developed at BAM. The simulated effective attenuation coefficients are compared with corresponding experimental results in order to establish a method for identification of low- and high-Z materials in the container. Finally, important applications of the proposed technique in the context of aviation security are discussed.
In order to enhance the supply chain security at airports, the German federal ministry of education and research has initiated the project ESECLOG (enhanced security in the air cargo chain) which has the goal to improve the threat detection accuracy using one-sided access methods. In this paper, we present a new X-ray backscatter technology for non-intrusive imaging of suspicious objects (mainly low-Z explosives) in luggage's and parcels with only a single-sided access. A key element in this technology is the X-ray backscatter camera embedded with a special twisted-slit collimator. The developed technology has efficiently resolved the problem related to the imaging of complex interior of the object by fixing source and object positions and changing only the scanning direction of the X-ray backscatter camera. Experiments were carried out on luggages and parcels packed with mock-up dangerous materials including liquid and solid explosive simulants. In addition, the quality of the X-ray backscatter image was enhanced by employing high-resolution digital detector arrays. Experimental results are discussed and the efficiency of the present technique to detect suspicious objects in luggages and parcels is demonstrated. At the end, important applications of the proposed backscatter imaging technology to the aviation security are presented.
Radiologic evaluation techniques are nondestructive testing (NDT) used to detect the bulk of explosives and contraband materials in large objects. As compared to conventional low-energy (<450 key) X-ray imaging, high-energy (>1 MeV) digital X-ray radiography is required for the NOT of large containers because of the need for high penetration through thick materials, sensitivity, and the ability to distinguish between low-and high-Z materials. Mobile, high-energy, and high-resolution radiologic techniques are useful to detect contraband and threat materials in digital radiographic images of containers with complex packing. This paper presents a mobile, high-energy X-ray radiographic technique for the in-field nondestructive inspection of cargo containers. The developed experimental technique consisted of a betatron as a high-energy (7.5 MeV) X-ray source and a high-resolution (400 mu m) matrix detector for the digital X-ray imaging. In order to evaluate the detection efficiency and image quality of the measurement technique, a test specimen was proposed that was made of a 3 mm thick steel container with an inner dimension of 60 x 30 x 40 cm(3) comprising different low-and high-Z materials. Image quality indicators were used to assess the essential image quality parameters such as image basic spatial resolution, effective attenuation coefficient, and signal-to-noise ratio (SNR). Experimental investigations were performed on a 6.1 m sea freight container with mockup dangerous materials in complex packing. Preliminary experimental results showed that the proposed technique was able to distinguish between liquids and solids, as well as detect contraband materials. Furthermore, a remarkable SNR of 400 was achieved in the measured digital X-ray images. The influence of temperature on X-ray radiation dose rate at different X-ray energies was also investigated. Finally, important applications of the proposed technique in the context of maritime security are discussed.
This paper presents a new X-ray backscatter technique (XBT) for non-destructive imaging of aerospace materials with only a single-sided access. It uses a special twisted slit collimator to inspect the whole object by changing the viewing direction of the X-ray backscatter camera. For the first time, the X-ray backscatter measurements were conducted using high-energy (>500 keV) X-ray sources. Experiments were performed on thick complex structured aluminium components, stringers and honeycomb structures to validate the applicability of the present technique to image small changes in the material properties and also to detect low-density material inclusions. In order to reduce the inspection time from hours to several seconds and to improve the image quality of the X-ray backscatter image, the backscattered signals were measured using a digital detector array with high spatial resolution (200 µm). The influence of the energy of the X-ray source and the slit width of the camera on the X-ray backscatter image were also investigated. In the proposed technique, the whole object is irradiated by an un-collimated X-ray beam resulting in a low image acquisition time of 3 min that facilitates the use of XBT for the real time NDT&E of aerospace materials.