The rotate-plus-shift C-arm trajectory. Part II. Exact reconstruction from less than 180° rotation.
The rotate-plus-shift C-arm trajectory. Part II. Exact reconstruction from less than 180° rotation.
复制标题
旋转加移位 C 形臂轨迹第二部分 小于 180° 旋转的精确重建
DOI：
10.1118/1.4944786
复制
发表时间：
2016
期刊：
影响因子：
3.8
通讯作者：
M. Kachelrieß
中科院分区：
文献类型：
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作者：
J. Kuntz;L. Ritschl;M. Knaup;M. Kachelrieß
目的CT重建要求测量范围内每个点的角度覆盖范围为180°或更大。因此，常见的轨迹使用180°加扇形角旋转。这有时与旋转等中心的平移相结合，以便实现具有不同于机械旋转中心的等中心的圆形轨迹或椭圆轨迹。对冗余测量的射线进行适当加权。在小于180°的角度覆盖的情况下，重建图像遭受有限的角度伪影。在旋转范围限于小于180°加上扇形角的机械构造中，可以通过向旋转运动添加一个或两个移位来扩展角度覆盖范围。如果丢失的角度小于扇形角，则移位可以完全补偿有限的旋转能力。MethodsThe作者给出的权函数可以被视为广义帕克权，它可以应用于图像重建前的原始数据。使用典型的基于移动的平板探测器的C形臂系统的几何结构模拟使用旋转加移位轨迹的Forbild体模的原始数据。过滤反投影（FBP）重建使用新的冗余权重进行和比较有限的角度扫描以及短扫描参考轨迹使用帕克weight.ResultsThe新的加权方法是准确的二维，和三维Feldkamp型重建，它是准确的中平面的FBP重建。所提出的权重在数学上与传统短扫描轨迹的帕克权重精确匹配。使用新权重的旋转加移位轨迹重建不会受到有限角度伪影的影响，而限制在180°以下而无移位的扫描显示出明显的伪影。旋转加移位扫描中的图像噪声与相应的短扫描中的图像噪声相当。结论新的权重函数可以使用旋转加移位C形臂轨迹和各种其他高级轨迹采集的数据的滤波反投影进行直接重建。
PurposeCT reconstruction requires an angular coverage of 180° or more for each point within the field of measurement. Thus, common trajectories use a 180° plus fan angle rotation. This is sometimes combined with a translation of the rotational isocenter in order to achieve circular trajectories with an isocenter different from the mechanical rotation center or elliptical trajectories. Rays measured redundantly are appropriately weighted. In case of an angular coverage smaller than 180°, the reconstructed images suffer from limited angle artifacts. In mechanical constructions with a rotation range limited to less than 180° plus fan angle, the angular coverage can be extended by adding one or two shifts to the rotational motion. If the missing angle is less than the fan angle, the shifts can completely compensate for the limited rotational capabilities.MethodsThe authors give weight functions that can be viewed as generalized Parker weights, which can be applied to the raw data before image reconstruction. Raw data of Forbild phantoms using the rotate‐plus‐shift trajectory are simulated with the geometry of a typical mobile flat detector‐based C‐arm system. Filtered backprojection (FBP) reconstructions using the new redundancy weight are performed and compared to FBP reconstructions of limited angle scans as well as short‐scan reference trajectories using Parker weight.ResultsThe new weighting method is exact in 2D, and for 3D Feldkamp‐type reconstructions, it is exact in the mid‐plane. The proposed weight shows a mathematically exact match with Parker weight for conventional short‐scan trajectories. Reconstructions of rotate‐plus‐shift trajectories using the new weight do not suffer from limited angle artifacts, whereas scans limited to less than 180° without shift show prominent artifacts. Image noise in rotate‐plus‐shift scans is comparable to that of corresponding short scans.ConclusionsThe new weight function enables the straightforward reconstruction using filtered backprojection of data acquired with the rotate‐plus‐shift C‐arm trajectory and a large variety of other advanced trajectories.
剂量最小化短扫描和超短扫描的锥束重建算法
DOI：
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发表时间：
2014
期刊：
影响因子：
--
作者：
Yan Xia;F. Dennerlein;S. Bauer;M. Berger;J. Hornegger;A. Maier
通讯作者：
A. Maier
影响因子：
3.8
作者：
Ritschl, Ludwig;Kuntz, Jan;Kachelriess, Marc
通讯作者：
Kachelriess, Marc
通过动态准直扇束和锥束 CT 中的冗余射线实现剂量减少
DOI：
10.1109/nssmic.2013.6829341
发表时间：
2013
期刊：
2013 IEEE Nuclear Science Symposium and Medical Imaging Conference (2013 NSS/MIC)
影响因子：
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作者：
Y. Xia;M. Berger;C. Riess;J. Hornegger;A. Maier
通讯作者：
A. Maier