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得到大量的信息。当双能计算机断层扫描（DECT）获得这些信息时，是一种很有前途的方法。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，我们提出了一种基于扇形波束几何的非对称吸收滤波器（AF）的DECT实现方法；我们称这种方法为非对称滤波法（AFM）。这种方法的优点是实现简单，因为对于多个实现只需要更换吸收过滤器。此外，该方法在一次扫描中执行DECT所需的测量。近年来，锥束CT由于具有比扇束CT更宽的测量范围，在高速测量中得到了相对广泛的应用。因此，在本研究中，我们提出了一种扩展版的锥形光束原子力显微镜，它结合了三维步进式原子力显微镜测量和迭代重建方法。由于DECT的广泛应用，需要一种具有实用价值的合适入门成本的实现方法。所提出的方法是满足这一需求的有力候选方法。

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.