Heuscher D, Brown K, Noo F
Philips Medical Systems, Cleveland, OH, USA.
Phys Med Biol. 2004 Jun 7;49(11):2219-38. doi: 10.1088/0031-9155/49/11/008.
This paper is about helical cone-beam reconstruction and the use of redundant data in the framework of two reconstruction methods. The first method is the approximate wedge reconstruction formula introduced by Tuy at the 3D meeting in 1999. The second method is a (exact) hybrid implementation of the exact filtered backprojection formula of Katsevich (2004 Adv. Appl. Math. at press) that combines filtering in the native cone-beam geometry with backprojection in the wedge geometry. The similarity of the two methods is explored and their image quality performance is compared for geometries with up to 112 detector rows. Furthermore, the concept of aperture weighting is introduced to allow the handling of variable amounts of redundant data. A reduction of motion artefacts using redundant data is demonstrated for geometries with 16, 32 and 112 detector rows using a pitch factor of 1.25. For scans with up to 100 rows, utilizing 50% of the redundant data provided excellent results without any introduction of cone-beam artefacts. For larger cone angles, an alternative approach that utilizes all available redundant data, even at reduced pitch factors, is suggested.
本文围绕螺旋锥束重建以及在两种重建方法框架下冗余数据的使用展开。第一种方法是图伊于1999年在三维会议上提出的近似楔形重建公式。第二种方法是卡特塞维奇精确滤波反投影公式（2004年《高等应用数学》即将发表）的一种（精确）混合实现方式，它将在原生锥束几何结构中的滤波与在楔形几何结构中的反投影相结合。探讨了这两种方法的相似性，并针对多达112排探测器的几何结构比较了它们的图像质量性能。此外，引入了孔径加权的概念，以处理不同数量的冗余数据。对于16、32和112排探测器的几何结构，使用1.25的螺距因子，展示了利用冗余数据减少运动伪影的效果。对于多达100排的扫描，利用50%的冗余数据能提供出色的结果，且不会引入任何锥束伪影。对于较大的锥角，建议采用一种即使在降低螺距因子的情况下也利用所有可用冗余数据的替代方法。
