Calculation of effective atomic numbers using a rational polynomial approximation method with a dual-energy X-ray imaging system

Abstract

The study aims to develop a rational polynomial approximation method for improving the accuracy of the effective atomic number calculation with a dual-energy X-ray imaging system. This method is based on a multi-materials calibration model with iterative optimization, which can improve the calculation accuracy of the effective atomic number by adding a rational term without increasing the computation time. The performance of the proposed rational polynomial approximation method is demonstrated and validated by both simulated and experimental studies. The twelve reference materials are used to establish the effective atomic number calibration model, and the value of the effective atomic numbers are between 5.444 and 22. For the accuracy of the effective atomic number calculation, the relative differences between calculated and experimental values are less than 8.5%for all sample cases in this study. The average calculation accuracy of the method proposed in this study can be improved by about 40%compared with the conventional polynomial approximation method. Additionally, experimental quality assurance phantom imaging result indicates that the proposed method is compliant with the international baggage inspection standards for detecting the explosives. Moreover, the experimental imaging results reveal that the difference of color between explosives and the surrounding materials is in significant contrast for the dual-energy image with the proposed method.

Virtual monochromatic imaging with projection-based material decomposition algorithm for metal artifacts reduction in photon-counting detector computed tomography

“…To evaluate the performance of the various MAR methods, we developed a program to simulate the two-dimensional (2D) spectral X-ray projections in a specific energy range at different angles from the three-dimensional (3D) digital objects [40,41]. A numerical method was used to simulate the PCD-CT imaging, which is based on the ray-tracing algorithm for calculating line integrals [42].…”

3D effective atomic number estimation for x-ray security inspection systems

“…[18][19][20] Then, Z ef f predictions of the objects are made by utilizing the previously obtained characteristic Z ef f -Ratio equation of each system. [14][15][16] As previously mentioned, the Z ef f -R equation varies based on the topology of each system. The unique characteristics of a system's Z ef f -R dynamics are determined by the current and voltage values of the X-Ray tube used, as well as the responses of the detectors to the beam.…”

“…In addition, studies based on the foundations of physics and aiming at a more robust determination of the effective atomic numbers of objects are prevalent. [11][12][13][14][15][16] These studies utilize the reactions of X-Ray detector cards to the beams passing through the scanned objects. When a beam of light passes through a scanned substance and reaches the detectors, its intensity decreases following the Beer-Lambert rule, which is represented by Eq.…”

“…Additionally, different linear, polynomial, or exponential relationships can be established between Z ef f and R. Based on the performance output, an appropriate Z ef f -R relation can be determined for each system. 14,16 Z ef f = 2.94…”

Ring artifacts suppression for X-ray CT images by fusion of dual-domain images based on improved UNet

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