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用于固体火箭发动机检测的窄角扇束CT采用重排算法进行图像重建,而重排算法用到的插值运算会造成投影数据的不准确,使得重建的CT图像质量下降。为了解决重排算法存在的问题,提出了一种新的直接卷积反投影算法。该算法避免了重排过程,直接利用不等间距平行束投影数据进行卷积反投影重建。为了验证直接卷积反投影算法的有效性,进行了数值仿真和实验验证,并将直接卷积反投影算法与重排算法进行对比。仿真和实验结果表明,直接卷积反投影算法比重排算法的图像重建时间短,直接卷积反投影算法较重排算法的重建图像质量高,这对固体火箭发动机缺陷的精确测量具有重要意义。
The narrow-angle fan beam CT used in the detection of solid rocket motors uses the rearrangement algorithm for image reconstruction, and the interpolation operation used in the rearrangement algorithm can cause inaccurate projection data and deteriorate the reconstructed CT image quality. In order to solve the problem of rearrangement algorithm, a new direct convolution backprojection algorithm is proposed. The algorithm avoids the rearrangement process and directly reconstructs convolution backprojection using projection data of unequal spacing parallel beams. In order to verify the effectiveness of the direct convolution backprojection algorithm, numerical simulation and experimental verification are carried out, and the direct convolution backprojection algorithm is compared with the rearrangement algorithm. Simulation and experimental results show that the direct convolution backprojection algorithm has shorter reconstruction time than the rearrangement algorithm, and the direct convolution backprojection algorithm has higher reconstruction image quality than the rearrangement algorithm, which is of great significance for the accurate measurement of solid rocket engine defects.