Journal of X-Ray Science and Technology - Volume 31, issue 2

Authors: Zhi, Weijuan | Zou, Jing | Zhao, Jintao | Xia, Xiaoqin

Article Type: Research Article

Abstract: BACKGROUND: Dual-energy computed tomography (DECT) can reconstruct electron density ρ e and effective atomic number Z eff distribution for material discrimination. Image-domain basis material decomposition (IBMD) method is a widely used DECT method. However, IBMD method cannot be used for mineral identification directly due to limitations of complex basis material determination, beam hardening artifacts, and inherent errors caused by approximate empirical formulas. OBJECTIVE: This study proposes an improved IBMD (IIBMD) method to overcome the above limitations. METHODS: In IIBMD method, the composition of basis material is optimized to obtain accurate decomposition coefficients, …which enables accurate ρ e and Z eff distribution. Moreover, the thickness of basis material is optimized to reduce the effect of beam hardening. Furthermore, two formulas in place of empirical formulas are proposed to calculate ρ e and Z eff . Finally, a threshold technique is applied to separate different mineral phases. RESULTS: Numerical simulations and practical experiments using a photon-counting detector CT system are implemented to verify IIBMD method. Results show that the relative errors of ρ e and Z eff for seven common minerals are down to 5%, lower than most of the existing DECT methods for rocks. Reasonable volume fraction results of mineral phases are thus obtained through threshold segmentation. CONCLUSIONS: This study demonstrates that the proposed IIBMD method has high practical value in mineralogical identification. Show more

Keywords: Dual-energy computed tomography, basis material decomposition, mineral quantitative characterization, basis material determination

DOI: 10.3233/XST-221324

Citation: Journal of X-Ray Science and Technology, vol. 31, no. 2, pp. 373-391, 2023

Authors: Jia, Tong | Shi, Liu | Wei, Cunfeng | Shi, Rongjian | Liu, Baodong

Article Type: Research Article

Abstract: Computed laminography (CL) is one of the best methods for nondestructive testing of plate-like objects. If the object and the detector move continually while the scanning is being done, the data acquisition efficiency of CL will be significantly increased. However, the projection images will contain motion artifact as a result. A multi-angle fusion network (MAFusNet) is presented in order to correct the motion artifact of CL projection images considering the properties of CL projection images. The multi-angle fusion module significantly increases the ability of MAFusNet to deblur by using data from nearby projection images, and the feature fusion module lessens …information loss brought on by data flow between the encoders. In contrast to conventional deblurring networks, the MAFusNet network employs synthetic datasets for training and performed well on realistic data, proving the network’s outstanding generalization. The multi-angle fusion-based network has a significant improvement in the correction effect of CL motion artifact through ablation study and comparison with existing classical deblurring networks, and the synthetic training dataset can also significantly lower the training cost, which can effectively improve the quality and efficiency of CL imaging in industrial nondestructive testing. Show more

Keywords: Computed laminography, rotational motion blur, image deblurring, deep learning

DOI: 10.3233/XST-221335

Citation: Journal of X-Ray Science and Technology, vol. 31, no. 2, pp. 393-407, 2023

Authors: Jeon, Pil-Hyun | Lee, Chang-Lae

Article Type: Research Article

Abstract: BACKGROUND: Recently, deep learning reconstruction (DLR) technology aiming to improve image quality with minimal radiation dose has been applied not only to pediatric scans, but also to computed tomography angiography (CTA). OBJECTIVE: To evaluate image quality characteristics of filtered back projection (FBP), hybrid iterative reconstruction [Adaptive Iterative Dose Reduction 3D (AIDR 3D)], and DLR (AiCE) using different iodine concentrations and scan parameters. METHODS: Phantoms with eight iodine concentrations (ranging from 1.2 to 25.9 mg/mL) located at the edge of a cylindrical water phantom with a diameter of 19 cm were scanned. Data were reconstructed with FBP, AIDR 3D, …and AiCE using various scan parameters of tube current and voltage using a 320 row-detector CT scanner. Data obtained using different reconstruction techniques were quantitatively compared by analyzing Hounsfield units (HU), noise, and contrast-to-noise ratios (CNRs). RESULTS: HU values of FBP and AIDR 3D were constant even when the iodine concentration was changed, whereas AiCE showed the highest HU value when the iodine concentration was low, but the HU value reversed when the iodine concentration exceeded a certain value. In the AIDR 3D and AiCE, the noise decreased as the tube current increased, and the change in noise when the iodine concentration was inconsistent. AIDR 3D and AiCE yielded better noise reduction rates than with FBP at a low tube current. The noise reduction rate of AIDR 3D and AiCE compared to that of FBP showed characteristics ranging from 7% to 35%, and the noise reduction rate of AiCE compared to that of AIDR 3D ranged from 2.0% to 13.3%. CONCLUSIONS: The evaluated reconstruction techniques showed different image quality characteristics (HU value, noise, and CNR) according to dose and scan parameters, and users must consider these results and characteristics before performing patient scans. Show more

Keywords: Deep learning reconstruction, CT angiography, image quality, filtered back projection, hybrid iterative reconstruction

DOI: 10.3233/XST-221356

Citation: Journal of X-Ray Science and Technology, vol. 31, no. 2, pp. 409-422, 2023

Authors: Sun, Yanmin | Han, Yu | Tan, Siyu | Xi, Xiaoqi | Li, Lei | Yan, Bin | Zhang, Yuan

Article Type: Research Article

Abstract: BACKGROUND: X-ray cone-beam computed laminography (CL) is widely used for large flat objects that computed tomography (CT) cannot investigate. The rotation angle of axis tilt makes geometric correction of CL system more complicated and has more uncertain factors. Therefore, it is necessary to evaluate sensitivity of the geometric parameters of CL system in advance. OBJECTIVE: This study aims to objectively and comprehensively evaluate sensitivity of CL geometric parameters based on the projection trajectory. METHODS: This study proposes the Minimum Deviation Unit (MDU) to evaluate sensitivity of CL geometric parameters. First, the projection trajectory formulas are derived …according to the spatial relationship of CL system geometric parameters. Next, the MDU of the geometric parameters is obtained based on the projection trajectories and used as the evaluation index to measure the sensitivity of parameters. Then, the influence of the rotation angle of the axis tilt and magnification on the MDU of the parameters is analyzed. RESULTS: At low magnification, three susceptible parameters (η , u 0 , v 0 ) with MDU less than 1 (° or mm) must be calibrated accurately to avoid geometric artifacts. The sensitivity of CL parameters increases as the magnification increases, and all parameters become highly sensitive when the magnification power is greater than 10. CONCLUSION: The results of this study have important guiding significance for the subsequent further parameter calibration. Show more

Keywords: Cone-beam, computed laminography, X-ray laminography, geometric parameters, sensitivity evaluation, parameters sensitivity

DOI: 10.3233/XST-221338

Citation: Journal of X-Ray Science and Technology, vol. 31, no. 2, pp. 423-434, 2023