Effciency Enhanced Mega Electronvolt Cone Beam Computed Tomography (EMECT) a succession project to the project X-ray 3D Computed Tomography with Mega Electronvolt Source (CTOMES)

在这个研究项目中，我们提出了一个对比度和图像质量的改进兆电子伏（MeV）锥束X射线成像。总体思路是通过引入高度优化的探测器侧滤波来提高探测到的初级辐射与散射辐射的比率。所提出的工作的关键部分将是与计算跟踪和校正所提出的方法的辅助空间分辨率损失相结合，以及提供了一种方法来跟踪实验的光谱系统响应的改进，并使用它进行精确的计算机模拟。高能（HE）工业X射线计算机断层扫描（CT）以超过一兆电子伏的能量工作的系统已经运行了十多年。然而，由于在这些能量下产生大量的散射辐射，这些系统通常被设计成使用通常高度准直的线性检测器的扇形束设置。HE装置可以从包含平板探测器的锥形束计算机断层扫描（CBCT）装置提供的速度和分辨率的提高中受益匪浅，因为它通常用于能量高达600千电子伏（keV）的较低X射线系统。然而，在MeV工业CT的背景下的锥束设置通常不具有足够的图像质量，这是由于辐射引起的伪影，其从样本、环境和检测器本身散射。在锥形束设置中，这种二次辐射不能通过准直来避免，而是背景信号的主要部分，并且降低对比度和空间分辨率。锥形束采集几何结构中的HE系统的射线照片遭受对象散射辐射的显著增加。此外，市售的平板探测器针对较低能量的X射线束进行了优化，其中闪烁层保持较薄，以避免成像系统的点扩散函数（PSF）的退化。对于MeV工业CT系统，由于X射线光子到信号的低的和非线性的转换，薄的磷屏导致低的检测效率。实验研究这些特性，并通过使用附加的检测器滤波引入图像对比度的改善项是本研究项目的目的。

In this research project proposal we propose a contrast and image quality improvement for Mega Electronvolt (MeV) cone beam X-Ray imaging. The overall idea is to improve the ratio of detected primary to scattered radiation by introducing highly optimized detector-sided filtering. Key part of the proposed work will be the combination with computational tracking and correcting the subsidiary spatial resolution loss of the proposed method, as well as providing a method to track experimentally the introduced improvements in spectral system response and use this for accurate in-silico simulations.High Energy (HE) industrial X-ray Computed Tomography (CT) systems operating with energies exceeding one Mega Electronvolt have been in operation for over a decade. However, due to the large amount of specimen-scattered radiation created at these energies, these systems are typically designed in a fan-beam setting using a linear detector which is usually highly collimated. HE setups could benefit greatly from the increase in speed and resolution provided by a Cone Beam Computed Tomography (CBCT) setup incorporating a flat-panel detector as it is typically used in X-ray systems with lower energies up to 600 Kilo Electronvolt (keV). However, a cone-beam setup in the context of MeV industrial CT often does not have sufficient image quality, due to artifacts caused by radiation, which is scattered from the specimen, the environment and the detector itself. In a cone beam setup such secondary radiation cannot be avoided by collimation, but is the main part of the background signal and decreases both contrast and spatial resolution. The radiographs of a HE system in cone-beam acquisition geometry, suffer from a significant increase in object-scattered radiation. Moreover, commercially available flat-panel detectors are optimized for lower energy X-ray beams, with a scintillation layer that is kept thin in order to avoid a degradation of the Point-Spread Function (PSF) of the imaging system. For MeV industrial CT systems the thin phosphorous screens cause a low detection efficiency due to the low and non-linear conversion of X-ray photons into signal. Investigating those properties experimentally and introducing an improvement term of image contrast by the use of additional detector filtering is purpose of this research project.