An Implementation of Energy-selective X-ray CT using an Asymmetric filter

X射线管产生宽光谱的光子能量，通过测量透射光谱的变化可以获得大量信息。当双能量计算机断层扫描（DECT）获得这些信息，它是一个很有前途的方法。DECT可以通过在每条光束线上进行两次测量来实现。在此之前，我们提出了一种在扇束几何结构上使用非对称吸收滤波器（AF）的DECT实现方法，我们称这种方法为非对称滤波器方法（AFM）。该方法的优点是其简单的实施，因为对于多个实施，仅需要更换吸收滤波器。此外，该方法在一次扫描中执行DECT所需的测量。最近，锥束CT已经变得相对广泛地用于高速测量，因为它具有比扇束CT更宽的测量范围。因此，在这项研究中，我们提出了一个扩展版本的锥束原子力显微镜，结合了三维步进式AF测量和迭代重建方法。由于DECT的普及，需要一种具有适当的实用价值的引入成本的实现方法。所提出的方法是一个强有力的候选人，以满足这一需求。

X-ray tubes produce a broad spectrum of photon energies and a great deal of information can be derived by measuring changes in the transmitted spectrum. When Dual-energy computed tomography(DECT) obtains this information, it is a promising method. DECT can be achieved by two measurements at each beam line. Previously, we proposed an implementation method of DECT with an asymmetrical absorption filter(AF) on the fan-beam geometry ; we called this method the asymmetric filter method(AFM). The advantage of this method is its simple implementation since only the absorption filters need to be replaced for multiple implementations. Furthermore, this method performs the measurement required by DECT in a one-time scan. Recently, cone-beam CT has become relatively widespread for high-speed measurements as it has a measuring range wider than that of the fan-beam CT. Therefore, in this study, we propose an extended version of the cone-beam AFM that combines a three dimensional step-type AF measurement and an iterative reconstruction method. Due to the spread of DECT, an implementation method with a suitable introductory cost for utility value is needed. The proposed method is a strong candidate to meet this need.