Efficient material decomposition method for dual-energy X-ray cargo inspection system

Lee, Donghyeon; Lee, Jiseoc; Min, Jonghwan; Lee, Byung-Cheol; Lee, Byeong-No; Oh, Kyung-Min; Kim, Jae Hyun; Cho, Seungryong

doi:10.1016/j.nima.2017.12.009

Cited by 25 publications

(6 citation statements)

References 26 publications

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“…Lee et al employs a different empirical approach by expressing a material-selective projection image as a linear combination of polynomial basis functions [18,19]. Then, for a choice of basis materials, a set of material-specific weighting factors are calculated through a least squares minimization against a calibration phantom.…”

Section: Empirical Methodsmentioning

confidence: 99%

A Semiempirical Transparency Model for Dual Energy Cargo Radiography Applications

Danagoulian¹

2023

Preprint

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Cargo containers passing through ports are scanned by non-intrusive inspection systems to search for concealed illicit materials. By using two photon beams with different energy spectra, dual energy inspection systems are sensitive to both the area density and the atomic number of cargo contents. Most literature on the subject assumes a simple exponential attenuation model for photon intensity in which only free streaming photons are detected. However, this approximation neglects second order effects such as scattering, leading to a biased model and thus incorrect material predictions. This work studies the accuracy of the free streaming model by comparing it to simulation outputs, finding that the model shows poor atomic number reconstruction accuracy at high-Z and suffers significantly if the source energy spectra and detector response function are not known exactly. To address these challenges, this work introduces a semiempirical transparency model which modifies the free streaming model by rescaling different components of the mass attenuation coefficient, allowing the model to capture secondary effects ignored by the free streaming model. The semiempirical model displays improvement agreement with simulated results at high-Z and shows excellent extrapolation to materials and thicknesses which were not included during the calibration step. Furthermore, this work demonstrates that the semiempirical model yields accurate atomic number predictions even when the source spectra and detector response are not known exactly. Using the semiempirical model, manufacturers can perform a simple calibration to enable more precise Z reconstruction capabilities, which has the potential to significantly improve the performance of existing radiographic systems.

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Section: Empirical Methodsmentioning

confidence: 99%

A Semiempirical Transparency Model for Dual Energy Cargo Radiography Applications

Danagoulian¹

2023

Preprint

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“…X-ray spectral information plays a crucial role in flux calculations, (1) dual-energy material decomposition, (2) artifact correction, (3) and the performance evaluation and calibration of X-ray detectors. (4) Spectral measurements necessitate the evaluation of each X-ray photon.…”

Section: Introductionmentioning

confidence: 99%

Charge-Sharing Detection Method Using Semiconductor Detectors with Different Electron and Hole Mobilities

Takagi,

Nishizawa

et al. 2024

Sensors and Materials

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The significance of X-ray spectral information is steadily growing. However, pile-up is becoming a pertinent problem at high dosage levels. Additionally, attempts to mitigate pile-up by reducing the surface area of the detector result in charge sharing, making accurate spectrum determination complicated. When materials such as cadmium telluride are employed as detectors, a significant disparity in the mobility of electrons and holes can lead to pulses in the opposite direction across multiple electrodes. We propose to identify charge-sharing events by detecting these opposing pulses. We found that eliminating events associated with negative pulses from the spectrum reduced the full width at half maximum of the peak from 15.9 to 14.4 keV. The proposed method improves the accuracy of spectral measurements under high flux to reduce the effect of charge sharing in single-point spectral measurements.

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“…X-ray radiography is an important tool in many security applications, including airport security [1]- [6], cargo inspection [7]- [10], and in the emergency response to a suspicious item that may contain explosives or other hazards, i.e., for bomb squads [11], [12]. Automating aspects of X-ray-based screening is attractive in terms of speed, cost, and safety and is an active area of study; see [13] for a recent review.…”

Section: Introduction and Related Workmentioning

confidence: 99%

Material Identification From Radiographs Without Energy Resolution

McCann

Guardincerri

Gonzales

et al. 2023

IEEE Trans. Comput. Imaging

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We propose a method for performing material identification from radiographs without energy-resolved measurements. Material identification has a wide variety of applications, including in biomedical imaging, nondestructive testing, and security. While existing techniques for radiographic material identification make use of dual energy sources, energy-resolving detectors, or additional (e.g., neutron) measurements, such setups are not always practical-requiring additional hardware and complicating imaging. We tackle material identification without energy resolution, allowing standard X-ray systems to provide material identification information without requiring additional hardware. Assuming a setting where the geometry of each object in the scene is known and the materials come from a known set of possible materials, we pose the problem as a combinatorial optimization with a loss function that accounts for the presence of scatter and an unknown gain and propose a branch and bound algorithm to efficiently solve it. We present experiments on both synthetic data and real, experimental data with relevance to security applications-thick, dense objects imaged with MeV X-rays. We show that material identification can be efficient and accurate, for example, in a scene with three shells (two copper, one aluminum), our algorithm ran in six minutes on a consumerlevel laptop and identified the correct materials as being among the top 10 best matches out of 8,000 possibilities.

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Efficient material decomposition method for dual-energy X-ray cargo inspection system

Cited by 25 publications

References 26 publications

A Semiempirical Transparency Model for Dual Energy Cargo Radiography Applications

A Semiempirical Transparency Model for Dual Energy Cargo Radiography Applications

Charge-Sharing Detection Method Using Semiconductor Detectors with Different Electron and Hole Mobilities

Material Identification From Radiographs Without Energy Resolution

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