摘要
为了对诊断目标进行瞬态辐射成像,提出了研制X射线聚焦成像系统,主要器件为一各向同性的X射线点光源及超环面弯曲晶体成像器。X射线照射至被成像物体后再投射到超环面晶体,经该凹面晶体聚焦后在X射线探测器表面成像。讨论了超环面晶体在布拉格几何结构中的聚焦成像特性,提出利用X射线源进行二维优化成像的适用条件。利用模拟软件对网格物体进行仿真成像,研究像距及光源尺寸对成像空间分辨力的影响,并据此确定了实验参量。设计的超环面弯晶采用云母材料,子午面曲率半径为290 mm,弧矢面曲率半径为190 mm。利用该系统进行了X射线背光成像实验,实验结果表明:系统的成像空间分辨力最高可达到34μm,能够满足聚爆辐射成像的要求;在光源尺寸较大时像距变化对成像效果有明显影响。
A focusing imaging X-ray system is developed for diagnostic target instantaneous imaging. The system is based on using an isotropic point X-ray source and a toroidally bent crystal. The X-ray beam intensity is modulated by the object attenuation, then enlarged using a toroidal crystal, finally, imaged using a detector downstream from the crystal. The focusing properties of the toroidally bent crystal in Bragg geometry are discussed. The applicable condi- tions for optimized two-dimensional imaging of X-ray source are proposed. Simulations of spatial resolution for toroid- ally bent crystals were done by using the ray-tracing method. The distance of detector to crystal and the source size effect the spatial resolution of the imaging system is researched. Toroidally bent crystal of mica with curvature radius 290 mm in the meridional plane and 190mm in the sagittal plane is used as imaging element in the experiments. It is demonstrated that the toroidally bent mica crystal could be used in X-ray imaging. By analyzing the image information of the sagittal direction, results show that the toroidally crystal imager has spatial resolution about 34 μm and the position of the detector will have an obvious effect to the imaging system with larger source.
出处
《仪器仪表学报》
EI
CAS
CSCD
北大核心
2012年第12期2761-2766,共6页
Chinese Journal of Scientific Instrument
基金
国家自然科学基金(11075226)资助项目
关键词
X射线
超环面晶体
成像
空间分辨
X-ray
toroidally bent crystal
imaging
spatial resolution
