Kohli V, King M A, Glick S J, Pan T S
Department of Nuclear Medicine, The University of Massachusetts Medical Center, Worcester 01655, USA.
Phys Med Biol. 1998 Apr;43(4):1025-37. doi: 10.1088/0031-9155/43/4/029.
The goal of this investigation was to compare resolution recovery versus noise level of two methods for compensation of distance-dependent resolution (DDR) in SPECT imaging. The two methods of compensation were restoration filtering based on the frequency-distance relationship (FDR) prior to iterative reconstruction, and modelling DDR in the projector/backprojector pair employed in iterative reconstruction. FDR restoration filtering was computationally faster than modelling the detector response in iterative reconstruction. Using Gaussian diffusion to model the detector response in iterative reconstruction sped up the process by a factor of 2.5 over frequency domain filtering in the projector/backprojector pair. Gaussian diffusion modelling resulted in a better resolution versus noise tradeoff than either FDR restoration filtering or solely modelling attenuation in the projector/backprojector pair of iterative reconstruction. For the pixel size investigated herein (0.317 cm), accounting for DDR in the projector/backprojector pair by Gaussian diffusion, or by applying a blurring function based on the distance from the face of the collimator at each distance, resulted in very similar resolution recovery and slice noise level.
本研究的目的是比较单光子发射计算机断层扫描（SPECT）成像中两种距离依赖性分辨率（DDR）补偿方法的分辨率恢复与噪声水平。两种补偿方法分别是在迭代重建之前基于频率-距离关系（FDR）的恢复滤波，以及在迭代重建中使用的投影仪/反投影仪对中对DDR进行建模。FDR恢复滤波在计算上比在迭代重建中对探测器响应进行建模更快。在迭代重建中使用高斯扩散对探测器响应进行建模，比在投影仪/反投影仪对中进行频域滤波的速度快2.5倍。与FDR恢复滤波或仅在迭代重建的投影仪/反投影仪对中对衰减进行建模相比，高斯扩散建模在分辨率与噪声的权衡方面表现更好。对于本文研究的像素尺寸（0.317厘米），通过高斯扩散在投影仪/反投影仪对中考虑DDR，或通过在每个距离处基于距准直器表面的距离应用模糊函数，可得到非常相似的分辨率恢复和切片噪声水平。
