论文标题
使用非线性正向模型的电子密度和有效原子数的迭代重建
Iterative Reconstruction of the Electron Density and Effective Atomic Number using a Non-Linear Forward Model
论文作者
论文摘要
对于材料识别，表征和定量，估计不取决于X射线计算机断层扫描（CT）系统（例如光谱响应）的详细规范的系统独立的材料特性很有用。独立的RHO-E和Z-E（SIRZ）是指估计使用双能X射线CT（DECT）扫描的对象的电子密度，Rho-E和有效原子数的独立材料特性的方法。当前的最新方法SIRZ-2进行了某些近似值，导致大原子编号（Z-E）材料的估计不准确。在本文中，我们提出了一个扩展名Sirz-3，它迭代地重建了未知的Rho-E和Z-E，同时避免了Sirz-2的限制近似值。与SIRZ-2不同，这允许SiRZ-3在Z-E的巨大值下精确地重建Rho-E和Z-E。 SIRZ-3依赖于使用新的非线性可区分前向测量模型，该模型将DECT测量数据表示为Rho-E和Z-E的直接分析函数。利用这个新的远期模型，我们使用迭代优化算法直接从DECT数据重建（或求解）Rho-E和Z-E。与SIRZ-2相比，我们表明使用SIRZ-3的性能提高的幅度随着Z-E值的增加而增加。
For material identification, characterization, and quantification, it is useful to estimate system-independent material properties that do not depend on the detailed specifications of the X-ray computed tomography (CT) system such as spectral response. System independent rho-e and Z-e (SIRZ) refers to a suite of methods for estimating the system independent material properties of electron density, rho-e, and effective atomic number, Z-e, of an object scanned using dual-energy X-ray CT (DECT). The current state-of-the-art approach, SIRZ-2, makes certain approximations that lead to inaccurate estimates for large atomic numbered (Z-e) materials. In this paper, we present an extension, SIRZ-3, which iteratively reconstructs the unknown rho-e and Z-e while avoiding the limiting approximations made by SIRZ-2. Unlike SIRZ-2, this allows SIRZ-3 to accurately reconstruct rho-e and Z-e even at large values of Z-e. SIRZ-3 relies on the use of a new non-linear differentiable forward measurement model that expresses the DECT measurement data as a direct analytical function of rho-e and Z-e. Leveraging this new forward model, we use an iterative optimization algorithm to reconstruct (or solve for) rho-e and Z-e directly from the DECT data. Compared to SIRZ-2, we show that the magnitude of performance improvement using SIRZ-3 increases with increasing values for Z-e.
