基于衬度的X射线光栅成像自适应通量优化  

Contrast-based fluence adaptation for dose optimization in grating-based X-ray imaging

作　　者：吴承鹏 王振天[1,2] 高河伟[1,2] 张丽[1,2] WU Chengpeng;WANG Zhentian;GAO Hewei;ZHANG Li(Department of Engineering Physics,Tsinghua University,Beijing 100084,China;Key Laboratory of Particle&Radiation Imaging(Tsinghua University)of Ministry of Education,Beijing 100084,China)

机构地区：[1]清华大学工程物理系,北京100084 [2]清华大学粒子技术与辐射成像教育部重点实验室,北京100084

出　　处：《中国体视学与图像分析》2022年第3期288-296,共9页Chinese Journal of Stereology and Image Analysis

摘　　要：相比于传统X射线成像,X射线光栅成像能够提供吸收衬度之外的折射衬度和暗场衬度图像。为了进一步推动该技术的实际应用,本文针对常用的傅里叶成分分析提出了一种基于衬度的自适应通量优化方法,并推导出相位步进过程中最优的通量分布形式。结果表明,针对折射衬度和暗场衬度最优的通量分布趋势正好相反,但相比于传统固定通量分布均能够显著降低目标衬度的噪声方差,反过来,也意味着在同等噪声下可以降低总的吸收剂量。而针对吸收衬度最优的通量分布就是传统固定通量分布,也说明传统固定通量是同时提取三种衬度的一种折中方案。Compared to traditional x-ray imaging,grating-based x-ray imaging(GBXI)can provide additional refraction and dark-field contrasts besides the absorption contrast.To promote more practical applications of this technology,we propose a contrast-based fluence adaptation method for the commonly used Fourier component analysis,and derive the optimal fluence distribution expressions in the phase-stepping process.The derivation results indicate that the corresponding optimal fluence distributions for the refraction and dark-field contrasts are in opposite trends,both of which can significantly reduce noise variance in the target contrast compared with traditional constant fluence distribution.In turn,it means that the proposed method can reduce the total absorption dose at the same noise level.Moreover,the optimal fluence distribution is just the traditional constant one,therefore,which is a compromise when simultaneously retrieving the three contrasts.

关 键 词：X射线光栅成像 剂量优化 相衬成像 暗场成像 

分 类 号：O434.1[机械工程—光学工程] TP391.41[理学—光学]