Wang G, Vannier M W
Division of Radiology Research, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, MO 63110.
Radiology. 1994 Apr;191(1):79-83. doi: 10.1148/radiology.191.1.8134601.
Stair-step artifacts in helical computed tomography (CT) are associated with inclined surfaces in longitudinal sections. The authors investigated the origin and the characteristics of the artifacts.
A cone phantom and a skull were dry-scanned with a helical CT scanner, and images were reconstructed by using the half-scan interpolation algorithm with combinations of detector collimation (1 and 5 mm), table feed (1, 2, 5, and 10 mm), and reconstruction interval (1, 2, 5, and 10 mm).
Stair-step artifacts were perceived in most instances. Stair-step artifacts arose from two sources: large reconstruction intervals and asymmetric helix interpolation, forming isoclosed curves and spirallike patterns in three-dimensional axial views, respectively.
To eliminate the stair-step artifacts, both the collimation and the table feed should be less than the longitudinal dimension of the important feature on inclined surfaces, and the reconstruction interval should be less than the table feed. Adaptive interpolation may correct the artifacts.
螺旋计算机断层扫描（CT）中的阶梯状伪影与纵向切片中的倾斜表面相关。作者研究了这些伪影的起源和特征。
使用螺旋CT扫描仪对锥形体模和颅骨进行干式扫描，并通过半扫描插值算法结合探测器准直（1和5毫米）、床进（1、2、5和10毫米）以及重建间隔（1、2、5和10毫米）来重建图像。
在大多数情况下都能观察到阶梯状伪影。阶梯状伪影源于两个来源：较大的重建间隔和不对称螺旋插值，分别在三维轴向视图中形成等封闭曲线和螺旋状图案。
为消除阶梯状伪影，准直和床进均应小于倾斜表面上重要特征的纵向尺寸，且重建间隔应小于床进。自适应插值可能会校正这些伪影。
