Materials identification

Dual-energy

The dual-energy method – which could be successfully applied in Digital radiography (radioscopy) and also in Tomography – is based on measurements of radiation attenuation coefficients acquired at two different X or Gamma rays energies from which, by means of a specialized and dedicated algorithm, could be computed the Atomic effective number (Zeff) and the Density (ρ) of the scanned objects. The method has large application in baggage control screening, food control, medicine (bone densitometry and mammography), minerals and drilling cores analysis, etc., domains where a specific material should be identified, a small variation should be detected or a better image contrast is required.
Dual-energy X-Ray Digital radiography (radioscopy) of various materials (Steel, Al, water and other organic materials) having thickness in steps between 1mm to 100mm. The graphs show the standard radioscopic image (top left), the Zeff map image (top right), the ρ map image (bottom right) and the equivalent thickness image (bottom left). The images reveals the Zeff and ? maps with colored palette for better identifying the materials and the equivalent thickness image gives each materials thickness. All information being very useful for operators of various X-Ray screening devices.
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Dual-energy X-Ray Tomogram of a hand-held baggage containing various materials, including an organic material named threat simulant. The images reveals the tomogram of the baggage cross-section (top left), the corresponding Zeff map (top middle) and ? map (top right), and also the automate threat recognition map (bottom left).
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Dual-energy X-Ray Tomogram of various materials usual found in the baggages, like soap, cheese, chocolate, toothpaste, deodorant together with threat simulant material. The graphs reveals the standard tomogram image of the cross-section (top left), the corresponding Zeff map image (top middle), the ρ map image (top right) and the automate threat recognition image (bottom left). Despite the small differences between materials’ Zeff and ρ values, the threat material still could be clearly detected.
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Dual-energy X-Ray Tomogram of linear mica-rich gneiss mineral rock. The image reveals the standard tomogram of the rock cross-section (left), the corresponding Zeff map (middle) and the ρ map (right). A better contrast is obtained in Zeff and ρ images from where an average density of 2.86 gr/cm3 and an average Atomic effective number of 10.23 was computed.
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Dual-energy X-Ray Tomogram of a extracted core collected downstream the confluence of the Danube River with the Danube-Black Sea Channel. The Density map (top right) reveals better the sedimentary details.
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Attenuation Coefficients technique

Materials identification could be made also by comparing the attenuation coefficients resulting from the tomographic reconstruction with standard data from database. In the top right figure is presented a gamma ray (Ir192) tomogram of various pure and mixed materials: silicon, aluminum, ceramic mass, selenium, iron, pressed iron, copper, pressed copper, pressed iron-copper mixture, brass and molybdenum, shaped as circular or rectangular material rods.
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The next image shows the extended histogram of attenuation coefficients of the tomogram. The attenuation peaks (corresponding to tomograms' materials) may be clearly observed, measured and compared with the standard values from the database. The accuracy of the method is around 1-2 % for a wide range of attenuation coefficients values and for a large class of usual materials.
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High-accuracy local density measurements

The method is based on measurement of a thin beam X or Gamma ray radiation attenuation through investigated objects and could reveal up to 0.5% variation in local density values. The technique is destined for evaluation of the weak mechanical points of sintered items by high-accuracy local density measurements. Following a software-generated path the investigated objects is automated scanned and the weak values are measured and graphically represented on screen.

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