The orientation code maps the pixel coordinate system I (column) J (row) K (slice) to right-handed coordinate system X Y Z. Characters R (right), L (left), A (anterior), P (posterior), I (inferior), S (superior) identify from direction.
RAI ¹, the default orientation², means
 Same orientation is called ITK RAI , DICOM LPS or Nrrd left-posterior-superior. 48 orientations are defined, but there are 24 valid orientations for DICOM. DICOM defines in Image Orientation (Patient) vectors for X and Y (6 direction cosines), Z is right-handed cross product. It is not relevant for DICOM classic series, they are usually sorted by Image Position (Patient) and Image Orientation (Patient). For multi-frame files Aliza will take care of correct export.
- X: patient Right to left
- Y: patient Anterior to posterior
- Z: patient Inferior to superior