连续谱X射线在ICT中的散射修正

在X射线工业计算机断层扫描成像技术（ICT）中，连续谱X射线透射物质时，发生了光子散射现象，有用信息连同散射光子一起进入探头形成伪影。如未修正，必引起赝像。利用X射线透射物质时的X光子散射遵循的Compton散射强度方程，建立了连续谱X射线完整精确的散射修正模型及其修正方法。为有效去除连续谱X光子的散射造成的图像伪影提供比较完善精确的修正模型和修正方法。     

X射线ICT检测中康普顿散射效应的影响与修正

在X射线工业计算机层析检测(ICT)中,由于X射线与物质作用发生康普顿散射效应,有用信息连同散射光子一起进入探头形成伪影。运用康普顿散射强度方程,结合X射线与物质相互作用的特性,推出X射线ICT中的散射修正公式,并由圆形截面工件散射模型,求出圆形截面工件的具体计算积分限。从探测器探测到的总光子数中减去康普顿散射光子数,即可有效去除散射光子造成的伪影。     

基于独立分量分析的X射线图像增强方法

为了改善由于散射造成的X射线检测图像对比度低,被测工件细节不易显示等缺点。针对退化图像中散射的分离,提出一种盲参数估计分离散射算法,该算法在假定图像由独立散射光谱组成的基础上,通过对散射偏振分析建立盲分离模型,来实现X射线图像的增强。采用小波变换得到图像子带图像,对盲参数间接估计。理论分析和实验结果表明,该算法在抑制散射的基础上有效的提高了图像的对比度和清晰度。     

X射线TICT中能谱硬化修正模型的数值分析

工业计算机断层扫描成像中，由于X射线能谱具有多色性，X射线在透射物质时，能量较低的射线优先被吸收，也即较高能量的X射线的衰减系数比较低能量的X射线的衰减系数小，射线随透射厚度增大，变得更易穿透，即发生了能谱硬化现象。对能谱硬化现象进行了分析，利用Beer定律和X射线与物质作用的特点，提出了能谱硬化修正模型和数值分析，结合Simpson公式，导出了X射线TICT中修正模型的数值解法及其修正方法。对修正后的衰减系数再作卷积反投影重构，即可有效消除能谱硬化造成的影响。     

基于深度学习建立模型去除工业CT伪影的技术研究

针对高压涡轮叶片工业CT检测过程中伪影干扰严重的问题,采用一种基于深度学习技术的伪影去除算法,建立去伪影自编码器模型,实现工业CT截面图像伪影的修正。通过试验证明,采用本算法训练获得的修正模型,能够有效去除高压涡轮叶片CT检测截面图像上的伪影干扰,并具有可推广适用性。     

非胶片射线检测技术（续）

4背散射成像 4．1物理基础 4．1．1概述 背散射成像是利用散射线而不是透射线来成像的。尽管一般X射线检测中散射的光子数与透射光子数一样多,但要使散射线成像却难得多。因此,背散射成像通常是一项数字技术。     

射线检测在复合材料无损检测中的应用

随着新型复合材料的迅速开发和应用，其制造过程监测、产品缺陷检测及质量评价等已成为不可缺少的环节。射线检测技术在复合材料无损评价中占有极其重要的地位。对现有的主要射线检测方法，包括X射线照相法、X射线实时成像法、射线计算机断层扫描法、射线断层形貌成像法、康普顿散射法及中子照相法等在复合材料质量评价中的应用状况进行了简要的评述，并指出复合材料射线检测的发展趋势。     

卷积神经网络在射线检测中的应用浅析

介绍近年来卷积神经网络在国内射线检测中的应用情况。该技术主要应用于焊缝缺陷识别、轮胎射线检测、去除图像伪影等方面。     

数字图象分析在材料检测中的应用

数字成象与分析首先广泛应用于工业领域中的自动控制和质量检测。尤其是在材料检测方面,充分证明了用计算机进行辅助无损检测的重要性。本文阐述了用X射线检测材料的新方法。这种新的X射线成象法是通过测量散射光(康普顿散射)来获得材料表面的三维信息。目前,用X射线自动检测铸件质量日趋广泛,其应用范围主要是航空航天以及汽车工业。 1 引言 质量检测的一个主要内容就是发现金属材料和现代复合材料内部的裂纹、夹杂和缩孔等缺陷。检验可在生产过程中进行,亦可在成品可靠性的研究中进行。在某些应用领域中,检验是为用户和消费者提供可靠性的必要程序。尤其是像汽车或飞机这类载人交通工具必须具有很高的可靠性。     

锥束工业CT射束硬化校正方法

锥束X射线CT系统中,X射线束具有宽能谱的特性,会导致X射线硬化效应的产生,从而使得重建图像中出现杯状和条状伪影等,故有必要研究硬化校正方法以减少硬化效应带来的影响。提出了基于试验能谱和蒙特卡罗模拟的多项式拟合硬化校正方法,基于试验测量X射线初始能谱,利用蒙特卡罗模拟得到透射厚度与多能投影的关系,再利用多项式拟合得到多能投影与等效单能投影的转换关系,从而实现硬化校正。分别采用该方法和传统的滤波片法对一铝制标准件进行射束硬化校正试验。结果表明,所提出的方法比滤波片法能更好地消除锥束CT的硬化伪影。     

基于变剂量扫描的X射线图像增强技术

实际工程中工件厚度变化的范围比数字成像器件所能记录的范围更大时,数字图像就会有灰度饱和或者灰度阴暗的区域,造成工件薄或厚处细节的损失.提出了一种基于变剂量扫描的X射线图像增强技术.该方法通过对工件进行连续的不同X射线剂量下的透照,获得一组序列图像.选取序列图像中包含信息最丰富的子图进行拼接融合,得到最终的增强图像.试验...     

Rayleigh to Compton ratio computed tomography using synchrotron radiation

The detection of X-ray photons scattered through a sample by the Rayleigh and Compton processes is used to perform tomographic images. In the present paper, we describe a new experimental arrangement and the corresponding reconstruction method. The scanning method is similar to the one used for first generation tomographs. A standard reconstruction algorithm gives two intermediate images, corresponding to the Compton and Rayleigh contributions. Quantitative comparisons are made with the aim to explain the difference of sensitivity between each scattering process. On both images artifacts are present, due to photon attenuation. Computing the ratio between those two images produces a map, free from artifacts, which represents the atomic number Z. Differentiation between polyethylene and an aqueous solution containing a low concentration of iodine (0.5 g l⁻¹) is easily performed. The experiments were carried out at the European Synchrotron Radiation Facility (ESRF), in Grenoble (France), on line ID15 B. As a result of the very high photon flux, short measurement times (about five seconds per point) are allowed, as well as a good spatial resolution. The voxel size is 1×1 mm² in the plane of the slice and 0.3 mm in the third direction.     

A study of multiple scattering background in Compton scatter imaging

The multiple scattering background in Compton scatter imaging at 662 keV is studied, both experimentally and by Monte Carlo radiation transport calculations, as a function of the scattering angle, scattering material (aluminium, brass and tin) and object thickness. A double-peak structure was observed in the pulse-height distribution for the thicker brass and tin objects and at the larger scattering angles (90° and 120°). In addition to the Compton peak, a second peak appeared at a higher energy. Monte Carlo transport simulations have revealed the origin of the second peak: photons that have scattered exactly twice before reaching the detector. The ratio of the multiple-scattered radiation to the total radiation detected was calculated as a function of the energy-window width around the Compton peak and scattering angle. The results of this study may help in the design of future Compton scatter imaging apparatus.     

Structure and conducting properties of thermoplastic composites of polypropylene and polyaniline protonated in solid state

The paper presents results of studies on composites made from polypropylene (PP) modified with polyaniline (PANI) doped with phenylophosphonic acid (PPA). For better miscibility of the components, lauryl gallate (LG) was added. Obtained results show that the amount of PPA and LG affect the thermal and structural properties of the composites. Changes of thermal properties, and particularly of structure, caused by addition of PPA and LG, affect the conductivity of the composites. The results discussed in the paper were obtained using differential scanning calorimetry (DSC) and optical microscopy as well as wide angle X-ray scattering (WAXS) and small angle X-ray scattering (SAXS).     

Influence of electronic structure on Compton scattering through comparing Cu-Ni alloys with Cu-Ni powder mixtures

The application fields of Compton scattering have been further broadened through the studies of theories and experiments as well as the electronic structure of the scatters. The relationship between the contents of binary alloys (also binary powder mixtures) and the number of Compton scattered photons has been thoroughly examined. The linear expression of the relationship has been obtained approximately according to the Compton scattering theory. And the relationship has been validated well through the Compton scattering experiments with the scatters of Cu-Ni binary alloys or Cu-Ni binary powder mixtures. Furthermore, it is found that the slope of Cu-Ni powder mixture series is steeper than that of Cu-Ni alloy series, and through the pseudopotential plane wave theory of DFT the microscopic principles of Compton scattering of Cu-Ni alloy and Cu-Ni powder mixture series have been discussed and compared with each other. The results show that the electronic structure is the main reason for the difference of the linear slopes, and the line slope of Cu-Ni powder mixtures series is steeper than that of Cu-Ni alloy series.