光学学报, 2016, 36 (8): 0834001, 网络出版: 2016-08-18
基于等值线拟合的X射线双能CT快速投影分解算法
Projection Decomposition Algorithm for X-Ray Dual-Energy Computed Tomography Based on Isotransmission Line Fitting
X射线光学 投影分解 等值线拟合 双能计算机断层成像 泰勒级数展开 X-ray optics projection decomposition isotransmission line fitting dual-energy computed tomography Taylor series expansion
摘要
针对双能计算机断层成像(DECT)图像重建算法中的非线性投影分解问题,提出一种基于等值线拟合的快速投影分解算法。建立高、低能投影线性近似的等值线拟合模型;基于泰勒级数展开,采用粗粒度正向计算、细粒度反向求解方法,获得高精度的解析解,生成等值线方程;将高、低能投影非线性联合求解问题转化为求解高、低能等值线的交点问题,从而实现双能投影的快速分解。实验结果表明,该方法避免了非线性迭代求解和投影查表匹配,在减小投影分解噪声波动的同时,显著提高了投影分解速度,与投影匹配方法相比分解速度提高约两个数量级。
Abstract
Aiming at the nonlinear projection decomposition problem in the image reconstruction by dual-energy computed tomography (DECT), a fast projection decomposition algorithm based on isotransmission line fitting is proposed. A linearly approximated isotransmission line fitting model is established for high and low energy projections. Based on the Taylor series expansion, the coarse-grain forward calculation and fine-grain reverse calculation are used to get the analytical solution with high accuracy, and the isotransmission line equations are generated. The nonlinear solution problem is transformed into the problem to solve intersections of high and low energy projection isotransmission lines, and thus the fast decomposition of dual energy projections is realized. The experimental results show that the proposed method avoids the nonlinear iteration and the projection matching, reduces noise fluctuation in projection decomposition, and improves the projection decomposition rate significantly. Compared to the projection matching method, the proposed method improves the decomposition rate by about two orders of magnitude.
李磊, 王林元, 蔡爱龙, 韩玉, 闫镔, 包尚联. 基于等值线拟合的X射线双能CT快速投影分解算法[J]. 光学学报, 2016, 36(8): 0834001. Li Lei, Wang Linyuan, Cai Ailong, Han Yu, Yan Bin, Bao Shanglian. Projection Decomposition Algorithm for X-Ray Dual-Energy Computed Tomography Based on Isotransmission Line Fitting[J]. Acta Optica Sinica, 2016, 36(8): 0834001.