Clinic for Diagnostic and Interventional Radiology (DIR), Heidelberg University Hospital, Im Neuenheimer Feld 420, 69120, Heidelberg, Germany.
Division of X-Ray Imaging and CT, German Cancer Research Center (DKFZ), Heidelberg, Germany.
Sci Rep. 2020 Dec 3;10(1):21099. doi: 10.1038/s41598-020-77904-3.
An evaluation of energy thresholding and acquisition mode for metal artifact reduction in Photon-counting detector CT (PCD-CT) compared to conventional energy-integrating detector CT (EID-CT) was performed. Images of a hip prosthesis phantom placed in a water bath were acquired on a scanner with PCD-CT and EID-CT (tube potentials: 100, 120 and 140 kV) and energy thresholds (above 55-75 keV) in Macro and Chess mode. Only high-energy threshold images (HTI) were used. Metal artifacts were quantified by a semi-automated segmentation algorithm, calculating artifact volumes, means and standard deviations of CT numbers. Images of a human cadaver with hip prosthesis were acquired on the PCD-CT in Macro mode as proof-of-concept. Images at 140 kV showed less metal artifacts than 120 kV or 100 kV. HTI (70, 75 keV) had fewer artifacts than low energy thresholds (55, 60, 65 keV). Fewer artifacts were observed in the Macro-HTI (8.9-13.3%) for cortical bone compared to Chess-HTI (9.4-19.1%) and EID-CT (10.7-19.0%) whereas in bone marrow Chess-HTI (19.9-45.1%) showed less artifacts compared to Macro-HTI (21.9-38.3%) and EID-CT (36.4-54.9%). Noise for PCD-CT (56-81 HU) was higher than EID-CT (33-36 HU) irrespective of tube potential. High-energy thresholding could be used for metal artifact reduction in PCD-CT, but further investigation of acquisition modes depending on target structure is required.
对光子计数探测器 CT（PCD-CT）与传统能量积分探测器 CT（EID-CT）的能量阈值和采集模式进行了金属伪影减少的评估。在配备 PCD-CT 和 EID-CT（管电压：100、120 和 140 kV）的扫描仪上，将髋关节假体放置在水浴中的假体幻影进行了图像采集，并在宏模式和棋盘模式下使用了能量阈值（55-75 keV 以上）。仅使用高能阈值图像（HTI）。使用半自动分割算法对金属伪影进行量化，计算伪影体积、CT 数的均值和标准差。在 PCD-CT 的宏模式下，对具有髋关节假体的人体尸体进行了图像采集，作为概念验证。与 120 kV 或 100 kV 相比，140 kV 图像的金属伪影更少。与低能量阈值（55、60、65 keV）相比，HTI（70、75 keV）的伪影更少。与 Chess-HTI（9.4-19.1%）和 EID-CT（10.7-19.0%）相比，Macro-HTI（8.9-13.3%）下皮质骨的伪影更少，而与 Chess-HTI（19.9-45.1%）相比，Macro-HTI（21.9-38.3%）和 EID-CT（36.4-54.9%）骨髓中的伪影更少。无论管电压如何，PCD-CT（56-81 HU）的噪声都高于 EID-CT（33-36 HU）。在 PCD-CT 中，可以使用高能阈值进行金属伪影减少，但需要进一步研究根据目标结构的采集模式。
