双模测量法消除编码孔成像的近场伪影  

Near-field artifact reduction in coded aperture imaging by double-mode measurement

作　　者：肖洒[1] 兰明聪[1] 党晓军[1] 张连平[1] 韦孟伏[1] 

机构地区：[1]中国工程物理研究院,绵阳621900

出　　处：《核技术》2013年第8期43-47,共5页Nuclear Techniques

基　　金：中国工程物理研究院基金(2011B0302054)资助

摘　　要：在编码孔成像技术中,由于存在近场伪影的干扰,降低了重建图像质量。为了消除这一影响,本文通过分析近场伪影的产生和消除原理,采用Geant4程序模拟了近场条件下300 keV单能源,通过MURA(19×19)嵌套编码孔成像,分别获得了单模和双模测量条件下重建得到的源分布图像。结果显示,单模测量得到的图像带有显著的近场伪影,而双模测量得到的图像中近场伪影得以消除。实际相机测量实验也获得了类似的结果。因此,与传统的单模测量法相比,双模测量法可以有效抑制和消除编码孔成像中的近场伪影,从而增强图像信噪比。Background： Due to the effect of near-field artifacts, the clearity of reconstructed image obtained by coded aperture imaging was decreased. Purpose： In order to explore a way to eliminate the effect and to enhance the image quality, a Geant4 simulation was performed in this work. Methods： On the basis of the principles of near-field artifact generation and elimination, coded aperture imaging of a 300 keV gamma source was simulated by Geant4 at near-field conditions with a mosaicked MURA（19 × 19） mask by single- and double-mode measurements, respectively. Results： The near-field artifacts were apparent in the images obtained by single-mode measurement, while they were almost eliminated by double-mode measurement. Similar results showed up in the imaging experiments with a commercial gamma camera. Conclusions： The near-field artifacts would be inhibited or even eliminated by the double-mode measurement otherwise from the conventional single-mode measurement, resulting with an enhanced signal-to-noise ratio （SNR） of reconstructed images.

关 键 词：双模测量法 编码孔成像 近场伪影 GEANT4 

分 类 号：TL99[核科学技术—核技术及应用]