强激光与粒子束2024，Vol.36Issue(9)：141-152,12.DOI:10.11884/HPLPB202436.240152
基于最大后验估计的编码孔图像重建算法
Coded-aperture image reconstruction algorithm based on maximum a posteriori estimation
秦玉瑞 1朱巴邻 1王忠海 1周荣 1杨朝文1
作者信息
摘要
Abstract
Image reconstruction algorithms significantly influence the imaging performance of coded-aperture gamma cameras.However,the widely used Maximum Likelihood Expectation Maximization(MLEM)algorithm falls short in effectively suppressing noise amidst stronger background interference because it relies on the system response matrix under ideal conditions.This paper presents corresponding research and improvements regarding the"pathological"nature of the MLEM algorithm.Firstly,the maximum a posteriori(MAP)algorithm was applied to the image reconstruction of coded aperture imaging,followed by an analysis of the selection methods for key parameters such as the neighborhood size and weight coefficient within the Gibbs prior function of the algorithm.Then,we conducted imaging experiments using the prototype of the coded-aperture gamma camera and compared the image reconstruction results of the MLEM algorithm and the MAP algorithm for the 22Na point source.In the range of 300 to 1200 iterations,the MLEM reconstructed images exhibited noticeable noise spots,with image quality progressively deteriorating as the iterations deepened.In contrast,the MAP reconstructed images did not present any significant noise spots.The average gradient of the reconstructed images was reduced by 26.45%to 49.16%compared to MLEM,and the contrast-to-noise ratio(CNR)was improved by 42.32%to 351.07%.Furthermore,we compared the reconstruction results of multi-point source images with 3×3 and 5×5 neighborhood sizes.The results indicate that smaller neighborhood size leads to a decrease in the brightness of the hotspots in the reconstructed images,consistent with the theoretical analysis.Finally,we compared the imaging results of the MLEM and MAP algorithms in two separate scenarios:one with greater distance and the other with stronger interference.In both scenarios,the MAP algorithm demonstrated better signal-to-noise ratio(SNR)performance.关键词
编码孔成像/最大似然期望最大化算法/最大后验估计/贝叶斯定理/马尔科夫随机场Key words
coded-aperture imaging/maximum likelihood expectation maximization/maximum a posteriori/Bayesian theorem/Markov random field分类
能源科技引用本文复制引用
秦玉瑞,朱巴邻,王忠海,周荣,杨朝文..基于最大后验估计的编码孔图像重建算法[J].强激光与粒子束,2024,36(9):141-152,12.
