getOrientation: Convert Direction Cosines to Anatomical Direction
Description
For cross-sectional DICOM images the orientation must be derived from
the Image Orientation (Patient) direction cosines.
Usage
getOrientation(xyz, delta = 0.0001)
Arguments
xyz
is a vector of direction cosines from
ImageOrientationPatient (0020,0037).
delta
is the tolerance around zero for comparisons.
Value
Anatomical direction shall be designated by the capital letters:
Aanterior
Pposterior
Rright
Lleft
Hhead
Ffoot
Details
C.7.6.2.1.1 Image Position And Image Orientation. The Image Position
(0020,0032) specifies the x, y, and z coordinates of the upper left
hand corner of the image; it is the center of the first voxel
transmitted. Image Orientation (0020,0037) specifies the direction
cosines of the first row and the first column with respect to the
patient. These Attributes shall be provide as a pair. Row value for
the x, y, and z axes respectively followed by the Column value for the
x, y, and z axes respectively. The direction of the axes is defined
fully by the patient's orientation. The x-axis is increasing to the
left hand side of the patient. The y-axis is increasing to the
posterior side of the patient. The z-axis is increasing toward the
head of the patient. The patient based coordinate system is a right
handed system; i.e., the vector cross product of a unit vector along
the positive x-axis and a unit vector along the positive y-axis is
equal to a unit vector along the positive z-axis.