基于源调制的锥束CT成像

Development of new cone-beam CT (CBCT) imaging methods is on high demand as the list of CBCT clinical applications keeps growing. Due to scatter contamination, current CBCT has a high CT number error of up to 350 Hounsfield Unit (HU). Newly-developed dual-energy CT (DECT) methods require two scans or costly hardware upgrades, which are not practical on current CBCT systems. We propose, for the first time, a single-scan DECT method for CBCT imaging with simultaneous scatter correction that does not require any changes to x-ray tube, detector, or sub-system controls. The method is based on the primary modulation approach invented by the PI of this proposal a few years ago. In this program, we will further improve the theory of primary modulation for better scatter estimation accuracy, and then add a new capability of single-scan DECT into the primary modulation approach. X-rays inside and outside of the modulator shadows have different energy spectra. The projection data are separated accordingly and used for reconstruction at two different x-ray mean energies. DECT material decomposition is finally performed on the CT images. Our preliminary phantom results show that the primary modulation method obtains high-quality CBCT images with an error of <20 HU, and successful achieves DECT material decomposition with an error of <5%. The overall goal of this project is to demonstrate the feasibility of single-scan DECT using primary modulation, to establish and optimize our method, and to investigate the method’s performance on simultaneous scatter correction and material decomposition using phantom experiments on clinical CBCT systems. Our research will may eventually lead to new CBCT-based clinical procedures in both radiation therapy and interventional radiology and a disruptive technology widely applicable on different CT systems.

新型成像技术缺失对锥束CT的影响随着其不断扩大的临床应用愈来愈明显。由于散射污染，锥束CT图像误差高达350 亨氏单位。现有双能CT成像技术需要双扫描或者价格昂贵的成像部件，并不适用于锥束CT系统。本项目致力于在锥束CT上开发在不需要改变x光管与探测器的情况下同时实现单扫描双能CT成像与高效散射校正的新方法。我们首先改进项目负责人发明的源调制理论以提高散射估计的精度。同时，采用相同的源调制数据采集，突破性地提出将投影数据根据不同有效能谱分离后分别使用迭代重建算法进行稀疏数据重建，实现单扫描双能CT成像。初步实验结果显示该方法能有效降低散射造成的成像误差至20亨氏单位以下，双能CT成像误差低于5%。本项目将继续优化源调制方法，提高实用性与稳定性，并在临床锥束CT系统上验证其成像精度。我们的研究将拓展锥束CT在放射治疗和介入手术中的临床应用，并有可能开发出通用于不同系统的新一代CT成像技术。

新型成像技术缺失对锥束CT的影响随着其不断扩大的临床应用愈来愈明显。由于散射污染，锥束CT图像误差高达350 亨氏单位。现有双能CT成像技术需要双扫描或者价格昂贵的成像部件，并不适用于锥束CT系统。本项目致力于在锥束CT上开发在不需要改变x光管与探测器的情况下同时实现单扫描双能CT成像与高效散射校正的新法。我们首先改进项目负责人发明的源调制理论以提高散射估计的精度。同时，采用相同的源调制数据采集，突破性地提出将投影数据根据不同有效能谱分离后分别使用迭代重建算法进行稀疏数据重建，实现单扫描双能CT成像。实验结果显示该方法能有效降低散射造成的成像误差至20亨氏单位以下，双能CT成像误差低于5%。我们的研究将拓展锥束CT在放射治疗和介入手术中的临床应用，并有可能开发出通用于不同系统的新一代CT成像技术。