Orientations and MetaImage Validation

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 orientation ² ³, means

  • X: patient Right to left

  • Y: patient Anterior to posterior

  • Z: patient Inferior to superior

[1] Same orientation is called ITK RAI , DICOM LPS or Nrrd left-posterior-superior. Sometimes towards notation is used, right to Left, etc.[2] 48 orientations are defined, but there are 24 valid orientation for DICOM. DICOM defines in Image Orientation (Patient) vectors for X and Y (6 direction cosines), Z is right-handed cross product.[3] Orientation means "close to", axes are not always aligned with coordinate system axes.


3D Slicer