When a Frame of Reference UID is present the segment shall be specified within that coordinate system, using the Pixel Measures, Plane Position (Patient) and Plane Orientation (Patient) Functional Groups. Since this defines the spatial relationship of the segment, the size of the segmentation frames need not be the same size, or resolution, as the image data used to generate the segment data.
If the Frame of Reference UID is not present, each pixel of the segmentation shall correspond to a pixel in a referenced image, using the Derivation Image Functional Group. Hence, the rows and columns of each referenced image will match the segmentation image.
The value of Purpose of Reference Sequence (0040,A170) in the Derivation Image Functional Group Macro shall be (121322, DCM, “Source Image for Image Processing Operation”). The value of Derivation Code Sequence (0008,9215) shall be (113076, DCM, “Segmentation”).