Near-field artifacts reduction in coded aperture push-broom Compton scatter imaging
Near-field artifacts reduction in coded aperture push-broom Compton scatter imaging
复制标题
编码孔径推扫康普顿散射成像中近场伪影的减少
DOI：
10.1016/j.nima.2020.163385
复制
发表时间：
2020-03-21
影响因子：
1.4
通讯作者：
Wei, Long
中科院分区：
文献类型：
--
作者：
Liu, Yantao;Xiao, Xiong;Wei, Long
最近，我们设计了一种新的方法，称为编码孔径推扫式康普顿散射成像(CAPCSI)，以改进背向散射X射线的使用。基于相关算法，近场伪影在CAPCSI中是明显的，尽管它们可以通过对掩模和反掩模的双重获取进行平均来部分地减少。在本文中，我们将最大似然期望最大化(MLEM)算法引入到CAPCSI中，以改善不需要双重捕获的伪影。首先，从近场伪影的产生推导出理论系统矩阵和模拟系统矩阵。然后对理想信号源进行了仿真，比较了相关算法和最大似然方法的不同算法。此外，还建立了CAPCSI原型来验证仿真的正确性。由于系统的不均匀性，采用光线驱动的方法预先推导出实验SM。最后给出了字符模体的成像方法。初步结果表明，MLEM对于点源的识别效果要好得多，对于复杂目标，MLEM比相关法能获得更清晰的背景。在仿真中，理论SM和模拟SM没有本质区别。然而，在实验中，由于综合考虑了近场效应和系统的非均匀性，实验SM的性能明显好于理论SM。这项工作将有助于增强CAPCSI的应用潜力。
Recently, we have devised a novel method called coded aperture push-broom Compton scatter imaging (CAPCSI) to improve the use of backscattered X-rays. Based on a correlation algorithm, near-field artifacts are obvious in the CAPCSI, although they could be reduced partially by averaging dual acquisitions of a mask and an antimask. In this paper, we introduce a maximum-likelihood expectation-maximization (MLEM) algorithm into the CAPCSI to improve the artifacts without dual acquisitions. First, a theoretical system matrix (SM) and a simulative SM were derived from the generation of near-field artifacts. Then, simulation for ideal sources was carried out to compare different algorithms of the correlation and the MLEM. Further, a CAPCSI prototype was set up to confirm the simulation. Because of the system nonuniformity, an experimental SM was derived in advance by a ray-driven way. Finally, imaging for character phantoms was presented. Preliminary results showed the MLEM performed much better for the point source and could obtain a cleaner background for complex objects than the correlation. In the simulation, the theoretical SM and the simulative SM were no essential difference. However, in the experiment, the experimental SM performed essentially better than the theoretical SM, because it took the near-field effects and the system nonuniformity into a comprehensive consideration. This work will help enhance the application potential of the CAPCSI.