X射线边缘增强编码成像技术研究

X-ray imaging is an important diagnostic tool in the fields of laser plasma, inertial confinement fusion and high energy density physics. However, the commonly used X-ray imaging techniques are aimed to obtain the intensity distribution image of the object to be measured, and there is no edge-enhancement feature. The development of X-ray edge-enhancement imaging technique is more conducive to improving the image quality of the boundary area and highlighting the details of the object, which has important values of research and application. In this project, we propose to develop X-ray edge-enhancement coded imaging technique, where spiral zone plate is at the first time used as a coded aperture. Based on the unique properties of spiral zone plate, the radial Hilbert transform is introduced into the coding image. The original intensity image is reconstructed by deconvolution algorithm, and the edge-enhancement image is reconstructed by optical simulation algorithm. According to the actual conditions of applications, the simulation program of X-ray coded imaging process is established, and the decoding program are further modified and optimized. The influences of non-ideal factors such as background noise and alignment error on imaging quality are studied. The structure parameters of spiral zone plate are determined, and the samples of spiral zone plate are fabricated. A coded camera is designed and developed, and experiments are carried out to obtain X-ray edge- enhancement images.

在激光等离子体、惯性约束聚变、高能量密度物理等研究领域，X射线成像是必不可少的诊断手段。然而，目前常用的X射线成像手段获得的都是目标物体的光强分布图像，不存在边缘增强特征。发展X射线边缘增强成像技术更有利于提高目标物体边界区域的成像质量，突出物体细节信息，具有重要的研究和应用价值。为此，本项目首次提出将螺旋波带片作为编码孔，开展X射线边缘增强编码成像技术研究。利用螺旋波带片的独特性质，在编码图中引入径向希尔伯特变换。通过退卷积算法重建获得原始强度图像，通过光学仿真算法重建获得边缘增强图像。考虑实际条件，建立编码成像过程仿真程序，对解码程序进行修正和优化。研究背景噪声、装调误差等非理想因素对成像质量的影响。确定结构参数，制备满足应用需求的螺旋波带片。研制编码相机系统，开展实验获取X射线边缘增强图像。

在激光等离子体、高能量密度物理等研究领域，X射线成像是必不可少的诊断手段。然而，目前常用的X射线成像手段获得的都是目标物体的光强分布图像，不存在边缘增强特征。发展X射线边缘增强成像技术更有利于提高目标物体边界区域的成像质量，具有重要的研究和应用价值。为此，本项目开展了基于二值化螺旋波带片的X射线边缘增强编码成像技术研究。主要研究内容和结果如下：（1）开发了基于光线追迹算法的编码成像数值模拟软件，建立了充分考虑不同材料对X 射线相移和吸收的材料参数数据库；开发了基于角谱理论的编码成像数值仿真程序，获得了考虑衍射效应、背景噪声、瞄准误差、装调误差、编码孔结构及材料等实际因素对编码成像质量的影响规律；为了提升重建图像质量，发展了基于压缩感知和深度学习的波带片编码成像重建算法，有效地消除了背景噪声和赝像等对重建图像的影响；（2）采用各种不同的工艺路线，研制了多块可见光和X射线螺旋波带片；成功研制了一台X射线螺旋波带片编码相机，完成了编码相机的光学设计、机械设计和系统调试等；（3）通过研制的可见光和X射线螺旋波带片，开展了相应的边缘增强成像原理验证实验；通过实验获得了待测可见光和X射线目标物体的边缘增强图像，实验结果符合理论预期。研究结果表明：本项目提出的X射线边缘增强编码成像技术无论是从基本原理上还是从工程实现上都是切实可行的，在激光等离子体高能量密度物理等领域具有重要应用价值。