具有加速因子的OSEM重建算法用于X射线荧光CT研究  

An accelerated OSEM reconstruction algorithm using an accelerating factor for X-ray fluorescence tomography

作　　者：孙鹏飞[1,2] 邓彪[1] 杨群[1] 杜国浩[1] 佟亚军[1] 肖体乔[1,2] 

机构地区：[1]中国科学院上海应用物理研究所嘉定园区上海201800 [2]中国科学院大学北京100049

出　　处：《核技术》2015年第6期30-35,共6页Nuclear Techniques

基　　金：国家自然科学基金(No.11275257、No.11105213、No.31100680、No.51274054、No.11375257、No.31300480);国家自然科学基金联合基金重点项目(No.U1232205/A0802);CAS-CSIRO合作研究项目(No.GJHZ1303)资助

摘　　要：有序子集最大期望值算法(Ordered Subsets Expectation Maximization,OSEM)具有较高的图像重建质量和较短的计算时间,已经被应用于内源CT(如SPECT、PET、同步辐射X射线荧光CT)的图像重建中。本文提出了一种具有加速因子的OSEM算法应用于X射线荧光CT的图像重建,通过引入加速因子h来调制校正因子的步长加快OSEM算法的收敛速度,研究了不同加速因子和不同子集数的AOSEM算法对重建图像质量的影响。计算机模拟及实验结果表明,在获得同等质量重建图像的同时,具有加速因子的OSEM算法的重建速度是常规OSEM的两倍。Background： The Ordered Subsets Expectation Maximization （OSEM） reconstruction algorithm has been widely applied in emission CT reconstruction, such as SPECT, PET and synchrotron radiation X-ray fluorescence CT （XFCT）. The quality of reconstructed image is better than other analytical methods such as filtered-back projection algorithm. However, the convergent rate of the OSEM is slow. Purpose： In order to speed up the convergent rate of OSEM, we want to investigate an improved OSEM algorithm. Methods： In this paper, we present an accelerated OSEM algorithm （AOSEM） by increasing the step size of the correction item and show its convergence characteristics with various subsets and accelerated factors. Results： The AOSEM algorithm is proposed and applied in XFCT image reconstruction. Comparing the two reconstruction algorithms, both the simulations and experimental results showed that AOSEM reached the same image quality as in OSEM but only about half the number of iterations when an accelerated factor was used. Conclusion： AOSEM can further speed up the convergence of OSEM when the accelerated factor h〉 1.

关 键 词：同步辐射 X射线荧光CT 图像重建质量 有序子集最大期望值算法 

分 类 号：TL99[核科学技术—核技术及应用]