Slit-Slat and Multislit-Slat Collimator Design and Experimentally Acquired Phantom Images from a Rotating Prototype.
Slit-Slat and Multislit-Slat Collimator Design and Experimentally Acquired Phantom Images from a Rotating Prototype.
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狭缝板条和多狭缝板条准直器设计以及通过旋转原型实验获取的幻像图像。
DOI：
10.1109/tns.2009.2033989
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发表时间：
2010
影响因子：
1.8
通讯作者：
Jaszczak,RonaldJ
中科院分区：
文献类型：
--
作者：
Metzler,ScottD;Accorsi,Roberto;Ayan,AhmetS;Jaszczak,RonaldJ
我们之前已经找到并验证了狭缝-狭缝（SS）几何效率和分辨率的表达式。这些公式表明，SS可能是成像中等大小物体或长轴向物体的良好选择，因为i)几何效率在狭缝ash-1附近增加[而不是针孔（PIN）的h-2]，在扇形光束（FB）附近降低或在平行光束（PB）附近保持不变]，其中点到狭缝平面的距离；（ii）横向分辨率与PIN相当，在小物体上优于FB和PB；iii)由于没有轴向放大，轴向分辨率比PIN差；iv)有一个大的轴向视野，不像PIN，这可能是有用的成像中型或长物体；v)不需要三维轨道（如螺旋轨道），因为每个切片都是完整的（如PB和FB）。我们已经开发了一个旋转原型SS准直器，能够单缝或多缝采集数据。焦距（FL）比典型PIN的焦距短，因为增加焦距需要更高的板条来保持分辨率；较高的板条降低了几何效率。在狭缝准直器周围使用了一个铅矩形盒来提供支撑和屏蔽。铅板，间隔与Rohacell泡沫，安装在一个3毫米间距的组件。我们已经用点源进行了初步的表征，并获得了微型热棒和冷棒幻影以及豪华的Jaszczak幻影。利用极大似然期望最大化算法对投影进行了重建，显示出较好的分辨率。对比表明，对于直径较小的物体，在相同分辨率下，SS比PB和FB更敏感。SS相对于PB和FB的优势随着期望分辨率的提高而增加。SS也可以用于产生非各向同性分辨率的投影的配置；由于PB不放大，SS有可能达到PB无法达到的横向分辨率，而FB对小物体的放大系数比SS小得多，因此SS有可能达到横向分辨率。实验结果表明，重建的幻影分辨率与理论预期一致。
We have previously found and validated expressions for slit-slat (SS) geometric efficiency and resolution. These expressions have suggested that SS may be a good choice for imaging midsize objects or objects that are long axially since i) the geometric efficiency increases near the slit ash-1[instead ofh-2for pinhole (PIN) and either decreases near the collimator for fan-beam (FB) or remains constant for parallel-beam (PB)], wherehis the distance from a point to the slit plane; (ii) the transverse resolution is comparable to that of PIN, which is better than that of FB and PB for small objects; iii) the axial resolution is worse than that of PIN since there is no axial magnification; iv) there is a large axial field of view, unlike PIN, which is likely to be useful when imaging midsize or long objects; and v) there is no need for three-dimensional orbits (e.g., helical) since each slice is complete (like PB and FB). We have developed a rotating prototype SS collimator that is capable of single-slit or multi-slit acquisition of data. The focal length (FL) is shorter than that of a typical PIN since increasing the FL requires taller slats to maintain resolution; taller slats reduce geometric efficiency. A lead rectangular box was used to provide support and shielding around the slit-slat collimator. Lead slats, spaced with Rohacell foam, were mounted in an assembly with 3 mm pitch. We have performed preliminary characterization with point sources and acquired micro hot- and cold-rod phantoms and a deluxe Jaszczak phantom. The projections have been reconstructed using a maximum likelihood expectation maximization algorithm and show good resolution. Comparisons indicate that SS is more sensitive than PB and FB for the same resolution for objects with smaller diameter. The advantage of SS over PB and FB increases as the desired resolution improves. SS can also be used in configurations that yield projections that have nonisotropic resolution; it is possible for SS to achieve transverse resolutions that are unreachable by PB, since PB does not magnify, and by FB, since its magnification factor for small objects is much smaller than that of SS. Experimental results show that the resolution of the reconstructed phantoms is consistent with theoretical expectations.
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DOI：
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期刊：
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影响因子：
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作者：
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