CIF:Small:Coded Aperture Spectral X-Ray Tomography

光谱层析成像已经成为医学成像和国土安全的关键成像方式。它提供了材料识别，为识别原子组成、化学目标和爆炸物提供了有用的线索。它依赖于不同化学物质的X射线吸收具有取决于所用X射线能量的特性的原理。因此，能够区分X射线能量的探测器使得能够区分具有相似X射线衰减特性的不同材料。不幸的是，能量分辨X射线探测器对于许多应用来说都贵得令人望而却步。其他探测器技术往往以成本换取采集速度，在许多情况下，实际限制需要有限的角度或次采样的投影几何，这会导致图像重建中的严重伪影。这项研究探索了编码的X射线照明投影，可以用标准的积分探测器捕获，同时为能量分辨图像重建提供信息。编码测量具有较低的辐射剂量。这项研究探索了彩色X射线编码投影，以绕过当前探测器的限制。与通过衰减的X射线测量对象不同，X射线首先以幅度和光谱编码，这些幅度和光谱以已知模式调制X射线场，有效地创建询问对象特定体素的低剂量结构化X射线束。仔细设计编码光圈，它们的放置，以及利用结构照明的快速计算逆算法的发展，可以在光谱层析成像的应用中提供优势。目前正在考虑各种计算机断层扫描(CT)几何结构，包括断层合成、扇形光束和锥形光束。用于验证基本理论概念的试验台是该项目的核心部分。

Spectral tomography has emerged as a key imaging modality for medical imaging and homeland security. It offers material discrimination providing useful cues for identifying atomic composition, chemical targets, and explosives. It relies on the principle that the X-ray absorption of different chemical materials has characteristics that depend on the energy of the X-rays used. Thus, detectors that can differentiate between X-ray energies make it possible to discriminate different materials having similar X-ray attenuation properties. Unfortunately, energy resolving X-ray detectors are prohibitively costly for many applications. Other detector technologies often trade cost for acquisition speed and, in many cases, practical limitations require limited angle or subsampled projection geometries that lead to severe artifacts in image reconstruction. This research explores coded X-ray illumination projections which can be captured with standard integrating detectors yet provide information for energy-resolved image reconstructions. The coded measurements have lower radiation dose. They can also be multiplexed for robustness in limited angle scenarios.This research explores colored X-ray coded projections to circumvent current detector limitations. Rather than measuring objects by the attenuated X-rays, the X-rays are first coded in amplitude and spectra that modulate the X-ray field in a known pattern, effectively creating lower-dose structured X-ray bundles that interrogate specific voxels of the object. Careful design of the coded apertures, their placement, and the development of fast computational inverse algorithms that exploit the structured illumination can provide advantages in the application of spectral tomography. Various computerized tomography (CT) geometries are being considered including tomosynthesis, fan-beam, and cone-beam. A test-bed for validating the underlying theoretical concepts is a central part of the project.