环形编码孔成像技术具有高的探测效率和信噪比, 是一种解决低强度脉冲辐射源成像较好的技术。基于该技术, 利用Geant4建立环形编码孔中子成像的模拟过程, 获取6个不同位置的点扩散函数(PSF)和编码图像。根据空间移变图像分块原理, 将图像分成矩形和圆形分块, 每一块图像用RL迭代法复原, 去除边界明显畸变的像素, 这些像素强度由相邻的图像块像素到边界距离的加权系数叠加而成。模拟结果表明, 该方法提高了图像复原效果, 能够更好地诊断射线区域的空间分布情况。

Ring-coded aperture imaging system is used to diagnose low intensity pulsed radiation source, which performs high resolution and high signal-to-noise ratio (SNR). Through Geant4 Monte Carlo toolkit, this paper simulates the system to get six point spread function (PSF) of point sources centered at different distance and the coded image of neutron source made up of a group of lines. Sectioned restoration algorithm is one of the methods to solve image restoration of space-variant point spread function. Firstly, the reconstructed image is divided to rectangle section or circle section. Each sub-section is restored by RL iterative method. Then, the boundary regions which bring obvious noise are removed. Those pixels are superposed by adjacent sections with weighting coefficient, which is the proportion of the distance between pixels and boundary. At last, the sub-frames are spliced together to construct integrated image. Computer simulations indicates the modified method is effective for removing the boundary distortion, which can diagnose the distribution of radiation source.