Huang Qiu, Zeng Gengsheng L
Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT 84108, USA.
Med Phys. 2006 Apr;33(4):997-1004. doi: 10.1118/1.2174719.
The pinhole collimator is currently the collimator of choice in small animal single photon emission computed tomography (SPECT) imaging because it can provide high spatial resolution and reasonable sensitivity when the animal is placed very close to the pinhole. It is well known that if the collimator rotates around the object (e.g., a small animal) in a circular orbit to form a cone-beam imaging geometry with a planar trajectory, the acquired data are not sufficient for an exact artifact-free image reconstruction. In this paper a novel skew-slit collimator is mounted instead of the pinhole collimator in order to significantly reduce the image artifacts caused by the geometry. The skew-slit imaging geometry is a more generalized version of the pinhole imaging geometry. The multiple pinhole geometry can also be extended to the multiple-skew-slit geometry. An analytical algorithm for image reconstruction based on the tilted fan-beam inversion is developed with nonuniform attenuation compensation. Numerical simulation shows that the axial artifacts are evidently suppressed in the skew-slit images compared to the pinhole images and the attenuation correction is effective.
针孔准直器目前是小动物单光子发射计算机断层扫描（SPECT）成像中首选的准直器，因为当动物非常靠近针孔放置时，它可以提供高空间分辨率和合理的灵敏度。众所周知，如果准直器围绕物体（例如小动物）在圆形轨道上旋转，以形成具有平面轨迹的锥束成像几何结构，那么采集到的数据不足以进行精确的无伪影图像重建。在本文中，安装了一种新型的斜缝准直器来代替针孔准直器，以便显著减少由该几何结构引起的图像伪影。斜缝成像几何结构是针孔成像几何结构的更一般化版本。多针孔几何结构也可以扩展到多斜缝几何结构。基于倾斜扇束反演开发了一种具有非均匀衰减补偿的图像重建解析算法。数值模拟表明，与针孔图像相比，斜缝图像中的轴向伪影明显受到抑制，并且衰减校正有效。
