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

作　　者：李磊[1] 王林元[1] 蔡爱龙[1] 韩玉[1] 闫镔[1] 包尚联[2] 

机构地区：[1]解放军信息工程大学信息系统工程学院,河南郑州450002 [2]北京大学重离子物理研究所,北京100871

出　　处：《光学学报》2016年第8期309-317,共9页Acta Optica Sinica

基　　金：国家863计划(2012AA011603);国家自然科学基金(61372172)

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。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.

关 键 词：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 

分 类 号：TP391[自动化与计算机技术—计算机应用技术]