当前基于光子计数探测器（PCD）的能谱CT（SCT）因硬件技术与成像模式问题，导致多级能谱数据分布一致性差、物质分解精度不高，且辐射剂量过大。为此，本项目拟提出基于PCD的医用多级能谱CT（Multi-Energy SCT，MeSCT）成像新模式，主要包括：(1) 开展周期性球管连续能级曝光时序设计与光谱调制关键技术及新模式下的成像系统建模研究，为后续多级能谱数据校正、物质分解及图像重建提供全新的系统模型支撑；(2) 开展新模式下非一致性能谱数据误差建模理论及相应数据校正策略研究，以服务于多物质分解与多级能谱图像重建新模型构建；(3) 开展新模式下多物质分解模型与多级能谱图像重建模型构建研究，以期实现低剂量条件下准确鲁棒的物质分解与能谱图像重建关键技术；(4) 开展成像性能及图像质量评价研究，以优化MeSCT低剂量精准成像新模式。本项目成果将对我国能谱CT成像领域的发展具有重要意义。

Photon counting detector (PCD) based spectral CT (SCT), due to its imaging mode problem, results in poor spectral data distribution consistency, lower the material decomposition accuracy and no significantly reduced radiation dose. To overcome the shortcomings of the PCD-SCT imaging, this project intends to actively develop a new imaging system model of multi-energy SCT (MeSCT) based on the PCD. The main contents include: (1) for proposing a new SCT imaging system model, we design a periodic tube continuous exposure timing scheme to support for the subsequent energy spectrum correction, material decomposition and image reconstruction; (2) with the new imaging system model, we first construct a new non-uniform spectral data error modeling and then build the corresponding spectral data correction strategies to serve for the new multi-material decomposition and multi-energy image reconstruction models; (3) we further construct new models of multi-material decomposition, multi-energy image iterative reconstruction with their dedicated model optimization algorithms to achieve accurate multi-material decomposition and robust image reconstruction under low-dose imaging protocols; (4) with the multi-material and multi-energy images, we carry out imaging performance and image quality evaluations to optimize the proposed MeSCT model with low-dose precision imaging. The gains of this project will be of great significance to the SCT imaging field in China.