High-energy dual-energy X-ray digital radiography imaging is mainly used in the material recognition of cargo inspection. We introduce the development history and principle of the technology and describe the data process flow of our system. The system corrects original data to get a dual-energy transparence image. Material categories of all points in the image are identified by the classification curve,which is related to the X-ray energy spectrum. For the calibration of classification curve, our strategy involves a basic curve calibration and a real-time correction devoted to enhancing the classification accuracy. Image segmentation and denoising methods are applied to smooth the image. The image contains more information after colorization. Some results show that our methods achieve the desired effect.
This paper gives an efficient approach to reconstruct moving multiple objects （multi-object）. Each object has independently rigid motion which includes translation and rotation. The traditional FBP algorithm can resolve the one-object motion problem rather well. However, it suffers from perceptible motion artifacts in multi-object cases. This paper proposes a new motion-compensated reconstruction approach with a pdori knowledge of the rigid motion model. Both an FBP-type and an ART-type algorithm were derived. In an effort to evaluate the proposed algorithms, we have performed numerical studies by using different rigid motion models. Quantitative results demonstrate that the proposed FBP-type and ART-type algorithms can recon- struct multi-object free of motion artifacts.
A three-dimensional （3-D） phantom for the density distribution of the plasmasphere is established. The imaging processes of the extreme ultraviolet （EUV） Imager are computer-simulated, in which the Earth shelter is treated as a main problem. A modified ART method is devised to resolve the incomplete data reconstruction problem to validate and evaluate the proposed methods. The cone-beam EUV data are simu- lated based on the 3-D phantom from both a circular and semi-circular trajectories. Quantitative reconstruc- tion results demonstrate the correctness of the proposed modified ART algorithm. The CT technique can be used to calculate the global density of the plasmasphere from the EUV data.
在某些用于在线控制的CT系统中,经常有必要在扫描过程中检查中间结果从而排除故障。然而实时的重建与体绘制对系统计算能力的要求非常高,难以实现。本文针对锥束CT提出了一整套实时重建可视化方法,并在最新的图形处理器Tesla C 1060上实现。与传统的工作方式不同,这种方法在扫描得到每一张投影后,实时显示重建过程的中间结果。通过这种方法,可以很清楚地观察到投影数据逐步合成三维重建结果的过程,也可以预先看到探测器的缺陷对重建结果造成的破坏。同时,这种方法也是实现4D CT可视化的一种有效途径。
