Abstract: Algebraic Reconstruction Technique (ART) is an important image reconstruction algorithm in CT, which is fit for reconstruction from incomplete projection data. The disadvantage of ART is that the reconstructing is time-consuming, in which the projection coefficient computation takes up over 90% of the reconstruction time. A fast algorithm for projection coefficient computation is presented in this paper, which can determine the grid index and calculate the length of the grid intercepted by the ray only requiring a simple incremental algorithm. The result shows that our algorithm is very effective and we can get a reconstruction speedup of over 6 times compared with the Siddon algorithm.

Key words: algebraic reconstruction technique (ART), image reconstruction, projection coefficient, Siddon algorithm

摘要： 代数重建法（Algebraic Reconstruction Technique ,ART）是一种重要的CT重建算法，适合于不完全投影数据的重建。缺点是重建速度慢，其中投影系数的计算占90%以上的重建时间。提出了一种快速投影系数计算方法，该方法只需通过简单的增量运算，即可确定网格编号并计算出射线与网格相交的长度。实验结果表明本文提出的方法非常有效，与Siddon算法相比，重建速度提高了6倍多。

关键词: 代数重建法（ART）, 图像重建, 投影系数, Siddon算法