双能谱CT(DSCT)可以重建被测物的材料分辨图像和能量分辨图像,进而区分物质,在医学、工业领域都有广泛的应用。图像重建算法是影响DSCT成像质量的关键技术。广义代数重建算法(E-ART)可以重建得到高质量的双基材料图像,但是该算法收敛速度较慢。针对该问题,提出一种加速收敛算法(AE-ART),其基本思想是通过为基函数添加权重来增大高能和低能投影曲线的夹角或减小高能和低能投影方程组系数矩阵条件数。使用口腔模型对水和骨双基材料分解进行模拟实验,实验结果表明:与E-ART算法相比,AE-ART算法的收敛速度提高了30%以上。

Dual-spectral computed tomography (DSCT) is used to reconstruct material- and energy-selective images to distinguish scanned object's materials and thus has numerous applications in medical and industrial fields. The image reconstruction method is vital in DSCT imaging, among which extended algebraic reconstruction technique (E-ART) can reconstruct basis material images with high quality. However, slow convergence limits its application. Herein, an accelerated extended algebraic reconstruction algorithm (AE-ART) was proposed. The main idea of the proposed algorithm is to increase the angle between the projection curves of high and low energies or to reduce the conditional number of coefficient matrix of those two projection curves by adding weights to the basis functions. Simulated experiments of dental phantom were conducted and the results indicated that the convergence rate of AE-ART was 30% higher than that of E-ART.