Kadrmas D J, Frey E C, Tsui B M
Department of Biomedical Engineering, The University of North Carolina at Chapel Hill, 27599, USA.
IEEE Trans Med Imaging. 1998 Jun;17(3):325-33. doi: 10.1109/42.712122.
Scatter compensation in Tl-201 single photon emission computed tomography (SPECT) presents an interesting challenge because of the multiple emission energies and relatively large proportion of scattered photons. In this paper, we present a simulation study investigating reconstructed image noise levels arising from various implementations of iterative reconstruction-based scatter compensation (RBSC) in Tl-201 SPECT. A two-stage analysis was used to study single and multiple energy window implementations of reconstruction-based scatter compensation, and RBSC was compared to the upper limits on performance for other approaches to handling scatter. In the first stage, singular value decomposition of the system transfer matrix was used to analyze noise levels in a manner independent of the choice of reconstruction algorithm, providing results valid across a wide range of regularizations. In the second stage, the data were reconstructed using maximum-likelihood expectation-maximization, and the noise properties of the resultant images were analyzed. The best RBSC performance was obtained using multiple energy windows, one for each emission photopeak, and RBSC outperformed the upper limit on subtraction-based compensation methods. Implementing RBSC with the correct choice of energy window acquisition scheme is a promising method for performing scatter compensation for Tl-201 SPECT.
由于存在多种发射能量以及散射光子所占比例相对较大,铊-201单光子发射计算机断层扫描(SPECT)中的散射补偿是一项具有挑战性的有趣课题。在本文中,我们开展了一项模拟研究,探究基于迭代重建的散射补偿(RBSC)在铊-201 SPECT中的不同实现方式所产生的重建图像噪声水平。采用两阶段分析方法来研究基于重建的散射补偿的单能量窗和多能量窗实现方式,并将RBSC与处理散射的其他方法的性能上限进行比较。在第一阶段,利用系统传递矩阵的奇异值分解,以一种独立于重建算法选择的方式分析噪声水平,所提供的结果在广泛的正则化范围内均有效。在第二阶段,使用最大似然期望最大化算法对数据进行重建,并分析所得图像的噪声特性。使用多个能量窗(每个发射光峰对应一个能量窗)可获得最佳的RBSC性能,并且RBSC的性能优于基于减法的补偿方法的上限。通过正确选择能量窗采集方案来实施RBSC,是一种对铊-201 SPECT进行散射补偿的很有前景的方法。