An investigation of inconsistent projections and artefacts in multi-pinhole SPECT with axially aligned pinholes
An investigation of inconsistent projections and artefacts in multi-pinhole SPECT with axially aligned pinholes
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DOI：
10.1088/0031-9155/56/23/010
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发表时间：
2011-12-07
影响因子：
3.5
通讯作者：
Meikle, S. R.
中科院分区：
文献类型：
--
作者：
Kench, P. L.;Lin, J.;Meikle, S. R.
多个针孔有利于最大限度地利用小型小动物单光子发射计算机断层扫描（SPECT）探测器的可用视场（FOV）。然而，当针孔轴向排列以优化扩展对象（如啮齿动物）的成像时，针孔投影的多路复用可能会产生不一致的数据，从而导致重建体积中的“鬼点”伪影。设计并实现了一种新型的带有挡板的四针孔准直器，以消除这些不一致的投影。通过模拟和物理模拟研究，研究了轴向排列针孔产生的伪影，以及挡板在去除不一致数据从而减少重建伪影方面的功效。使用Defrise幻影进行SPECT，以研究准直器设计对视场利用率和轴向模糊效果的影响。与没有挡板的SPECT相比，使用挡板获得的多针孔SPECT具有更少的伪影和更高的定量精度。使用四个针孔定位在一个正方形最大化可用的FOV，增加采集灵敏度和减少轴向模糊的影响。这些发现支持使用挡板来消除轴向排列针孔引起的不一致投影数据，并改善小动物SPECT重建。
Multiple pinholes are advantageous for maximizing the use of the available field of view (FOV) of compact small animal single photon emission computed tomography (SPECT) detectors. However, when the pinholes are aligned axially to optimize imaging of extended objects, such as rodents, multiplexing of the pinhole projections can give rise to inconsistent data which leads to 'ghost point' artefacts in the reconstructed volume. A novel four pinhole collimator with a baffle was designed and implemented to eliminate these inconsistent projections. Simulation and physical phantom studies were performed to investigate artefacts from axially aligned pinholes and the efficacy of the baffle in removing inconsistent data and, thus, reducing reconstruction artefacts. SPECT was performed using a Defrise phantom to investigate the impact of collimator design on FOV utilization and axial blurring effects. Multiple pinhole SPECT acquired with a baffle had fewer artefacts and improved quantitative accuracy when compared to SPECT acquired without a baffle. The use of four pinholes positioned in a square maximized the available FOV, increased acquisition sensitivity and reduced axial blurring effects. These findings support the use of a baffle to eliminate inconsistent projection data arising from axially aligned pinholes and improve small animal SPECT reconstructions.