论文标题
宠物启用双能量CT：图像重建和概念验证计算机模拟研究
PET-enabled Dual-Energy CT: Image Reconstruction and A Proof-of-Concept Computer Simulation Study
论文作者
论文摘要
标准双能计算机断层扫描（CT）使用两种不同的X射线能量来获得能量依赖性组织衰减信息，以允许定量材料分解。双能CT和正电子发射断层扫描（PET）的综合使用可以对癌症和许多其他疾病的疾病状态更全面地表征。但是，双能CT与PET的集成并不是微不足道的，要么需要昂贵的硬件升级或增加辐射剂量。本文提出了一种新型的双能CT成像方法，该方法由PET/CT上的PET数据启用。该方法没有使用最大的可能性衰减和活动（MLAA）算法来利用第二次X射线CT扫描，而是从PET排放数据中利用飞行时间的PET图像重建。然后将高能量伽马射线CT图像与PET/CT的低能X射线CT结合使用，以提供一对双能量CT图像。标准MLAA重建的主要挑战是重建的511 KEV衰减图中存在的高噪声，这不会损害PET活动过多的重建，但会显着影响Gamma-Ray CT的性能进行材料分解。为了克服问题，我们进一步提出了一个内核MLAA算法，以利用可用的X射线CT图像利用先前的信息。我们进行了计算机模拟，以测试材料分解任务的概念和算法。模拟结果表明，这种启用PET的双能CT方法有望用于定量材料分解。提出的方法可以轻松地在飞行时间宠物/CT扫描仪上实现，以同时进行宠物和双能量CT成像。
Standard dual-energy computed tomography (CT) uses two different X-ray energies to obtain energy-dependent tissue attenuation information to allow quantitative material decomposition. The combined use of dual-energy CT and positron emission tomography (PET) may provide a more comprehensive characterization of disease states in cancer and many other diseases. However, the integration of dual-energy CT with PET is not trivial, either requiring costly hardware upgrade or increasing radiation dose. This paper proposes a novel dual-energy CT imaging method that is enabled by the already-available PET data on PET/CT. Instead of using a second X-ray CT scan with a different energy, this method exploits time-of-flight PET image reconstruction via the maximum likelihood attenuation and activity (MLAA) algorithm to obtain a 511 keV gamma-ray attenuation image from PET emission data. The high-energy gamma-ray CT image is then combined with the low-energy X-ray CT of PET/CT to provide a pair of dual-energy CT images. A major challenge with the standard MLAA reconstruction is the high noise present in the reconstructed 511 keV attenuation map, which does not compromise the PET activity reconstruction too much but significantly affects the performance of the gamma-ray CT for material decomposition. To overcome the problem, we further propose a kernel MLAA algorithm to exploit the prior information from the available X-ray CT image. We conducted a computer simulation to test the concept and algorithm for the task of material decomposition. The simulation results indicate that this PET-enabled dual-energy CT method is promising for quantitative material decomposition. The proposed method can be readily implemented on time-of-flight PET/CT scanners to enable simultaneous PET and dual-energy CT imaging.
