Asian Journal of Nuclear Medicine

Volume 1 Number 1, April 2001



目的 分析比較不同子集的選取對PET重建圖像質量以及重建收斂速度的影響。方法 採用仿真Phantom模型在不同子集劃分和不同迭代次數下進行重建並分析其結果。結果 當子集個數和迭代次數的乘積相同時,重建所需的計算時間相同;相同迭代次數下重建圖像質量隨著子集個數的增加而提高,但並非子集個數越多越好。結論 為了在提高計算時間的同時確保重建圖像的質量,在實際計算中必需選取合適的子集個數。


Study of Ordered Subsets Expectation Maximization(OS-EM) Algorithm Based on Different Subsets*

Wu Zhaoxia1, Liu Li2, Chai Xinyu3, Cheng Jingzhi1
1Department of Biomedical Engineering, Xi'an Jiaotong Univ., 710049.
2Department of Modern Physics, University of Science and Technology of China, 230027.
3Department of Biomedical Engineering , Shanghai Jiaotong Univ., 200030.

Purpose: compare influence on positron emission tomography (PET) reconstruction image quality and convergence rate of different subsets. Method: study the reconstruction results of simulated phantom based on different selection of subset level and iteration time. Results: approximately computation time is required with same product of level and iteration time, the quality of image with big level is better than small one under the same iteration time, but it does not increase monotonously, there is a tradeoff between subset level and image quality. Conclusion: to improve computation speed while guaranteeing image quality, we should select proper level of subset in practice. (Asian J Nucl Med 2001;1:13-15)

Key Words : OS-EM; Subset level; Image reconstruction

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