旋转调制器成像的蒙特卡罗仿真及图像重建

Monte Carlo Simulation and Image Reconstruction of Rotating Modulator Imaging

基于时间调制的旋转调制器(RM)成像技术是一种可以对硬X射线、γ射线等成像的技术。为利用RM成像技术优势,开展了RM技术在核监测领域应用的研究工作。通过蒙特卡罗仿真,模拟准直器旋转过程,布置7个NaI探测器测量,获得受调制的探测器输出,再用NCAR、MLEM和OSEM算法分别对输出数据进行重建。相对NCAR算法,MLEM算法在抑制噪声的同时,不会在重建源图像周围引入随机边缘。OSEM算法可以加速MLEM算法的收敛过程,提高计算速度。MLEM和OSEM重建图像的角度分辨率可达1.2°,与仿真系统几何角度分辨率比较,达到了约3.8倍的超分辨能力。

Rotating modulator imaging is a temporal modulating technology which can be used to image hard X -ray,γ-ray,etc.It is now studied for implementation in nuclear monitoring applications .A virtual RM system consisting of 7 NaI detectors is established and its imaging procedure is simulated based on Monte Carlo meth -od.The detector outputs are reconstructed using NCAR ,MLEM and OSEM algorithm respectively .Reconstruc-tion shows that MLEM algorithm can suppress noise as NCAR algorithm without additional random sidelobes . OSEM can improve convergence of MLEM .Reconstructed images of MLEM and OSEM algorithm manifest an angular resolution of 1.2°,which is about 3.8 times better than the geometric resolution .