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Table 2 Calculation of directional cosines

From: Quantifying the variability between multiple multiplanar reconstructions of computed tomography scans

Axis component Primary axis
x y z
x xx yx zx = xyyz-xzyy
y xy yy zy = xzyx-xxyz
z xz yz zz = xxyy-xyyx
  1. The DICOM header tag Image Orientation (0020, 0037) contains directional cosines describing unit vectors along the first row (x axis) and first column (y axis) of each reconstruction slice relative to the native scan. Since the z axis is orthogonal to the x and y axes, the directional cosines for this axis can be calculated as shown