Comparison of circular and polygonal planar orbits for pinhole and slit-slat SPECT.
Comparison of circular and polygonal planar orbits for pinhole and slit-slat SPECT.
复制标题
针孔和狭缝板条 SPECT 的圆形和多边形平面轨道的比较。
DOI：
10.1109/tns.2009.2013465
复制
发表时间：
2009
影响因子：
1.8
通讯作者：
Metzler,ScottD
中科院分区：
文献类型：
--
作者：
Accorsi,Roberto;Ayan,AhmetS;Metzler,ScottD
采用解析公式和蒙特卡罗模拟方法，计算并比较了针孔和缝条准直时，圆轨道和多边形轨道在视场内不同点处的灵敏度。结果表明，对于给定的缝隙-板条准直器，与FoV相切的N边多边形轨道通常提供比与相同孔径角一致的最紧圆形轨道低的平均灵敏度，但具有更好的空间分辨率，可以用恒定的灵敏度来交换分辨率比较。这通常会使多边形轨道略占优势。然而，这种优势取决于轨道和FoV之间必须允许的间隙，并且该间隙迅速减小，甚至在留下几毫米的空间时就消失了，这在实践中是适应机械约束所必需的。对于针孔准直器，切线多边形轨道的优点更加一致，但当考虑间隙时，再次得出类似的结论。狭缝板条和针孔准直在一个单一的横向平面之间的恒定分辨率的直接比较被证明是可能的，与典型的小动物成像应用程序的参数，只有具有优良的固有分辨率的探测器，在这种情况下，针孔准直被证明是更敏感的放大几何形状，但减少轴向FoV和增加轴向模糊也应该被考虑为一个更完整的比较。
Analytic formulas and Monte Carlo simulation are used to calculate and compare the sensitivity of circular and polygonal orbits at different points in the Field of View (FoV) for both pinhole and slit-slat collimation. Results show that for a given slit-slat collimator anN-sided polygonal orbit tangent to the FoV generally provides average sensitivity lower than the tightest circular orbit consistent with the same aperture angle, but with better spatial resolution that can be traded for sensitivity for a constant-resolution comparison. This generally results in a slight advantage for the polygonal orbit. However, this advantage depends on the clearance that must be allowed between the orbit and the FoV and decreases quickly, vanishing when even a few millimeters of space are left, which in practice is necessary to accommodate mechanical constraints. For a pinhole collimator the advantage for the tangent polygonal orbit is more consistent, but similar conclusions are reached again when clearance is considered. A direct comparison at constant resolution between slit-slat and pinhole collimation in a single transverse plane is shown to be possible with parameters typical of small-animal imaging applications only for detectors with excellent intrinsic resolution; in this case, pinhole collimation is shown to be more sensitive in magnifying geometries, but reduced axial FoV and increased axial blurring should also be considered for a more complete comparison.