LI Quan1， CHEN Ping1,2， PAN Jin-xiao1
（1. Shanxi Key Laboratory of Signal Capturing & Processing, North University of China, Taiyuan 030051, China；2. Key Laboratory of Computed Tomography, Institute of Automation, Chinese Academy of Sciences, Beijing 100190, China）
Abstract： In conventional computed tomography (CT) reconstruction based on fixed voltage, the projective data often appear overexposed or underexposed, as a result, the reconstructive results are poor. To solve this problem, variable voltage CT reconstruction has been proposed. The effective projective sequences of a structural component are obtained through the variable voltage. The total variation is adjusted and minimized to optimize the reconstructive results on the basis of iterative image using algebraic reconstruction technique (ART). In the process of reconstruction, the reconstructive image of low voltage is used as an initial value of the effective projective reconstruction of the adjacent high voltage, and so on until to the highest voltage according to the gray weighted algorithm. Thereby the complete structural information is reconstructed. Simulation results show that the proposed algorithm can completely reflect the information of a complicated structural component, and the pixel values are more stable than those of the conventional.
Key words： variable voltage computed tomography (CT) reconstruction; total variation-algebraic reconstruction technique (TV-ART) algorithm; gray weight； effective projection
CLD number： TP391 Document code： A
Article ID： 1674-8042(2014)04-0052-05 doi： 10.3969/j.issn.1674-8042.2014.04.010
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变电压CT重建的灰度加权算法
李权1， 陈平1,2， 潘晋孝1
（1. 中北大学 信息探测与处理山西省重点实验室， 山西 太原 030051；2. 中国科学院自动化研究所 中国科学院分子影像重点实验室， 北京 100190）
摘要:常规固定电压的CT重建， 因成像系统动态范围受限， 投影数据易出现过曝光和欠曝光共存现象， 造成信息缺失多， 成像质量差， 为此提出变电压CT重建。 通过变电压获得跟工件有效厚度相匹配的有效投影序列， 在ART迭代图像的基础上， 调整全变差使其最小化， 从而优化重建。 在重建过程中， 依据灰度加权， 把低电压的重建图像作为初值， 应用在相邻高电压有效投影重建中， 得到相邻高电压的重建图像， 依次类推直至最高电压。 至此， 工件的全部结构信息重建完毕。 仿真结果表明， 灰度加权算法不仅实现了变电压图像信息的完整重建， 而且像素值更加稳定。
关键词:变电压CT重建； TV-ART算法； 灰度加权； 有效投影
引用格式：LI Quan， CHEN Ping， PAN Jin-xiao. Gray weighted algorithm for variable voltage CT reconstruction. Journal of Measurement Science and Instrumentation, 2014, 5(4): 52-56. [doi: 10.3969/j.issn.1674-8042.2014.04.010]
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