A.51 Segmentation IOD
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## A.51 Segmentation IOD

### A.51.1 Segmentation IOD Description

The Segmentation Information Object Definition (IOD) specifies a multi-frame image representing a classification of pixels in one or more referenced images. Segmentations are either binary or fractional. If the referenced images have a defined frame of reference, the segmentation instance shall have the same frame of reference and is not required to have the same spatial sampling or extent as the referenced images. If the referenced image does not have a defined frame of reference, the segmentation instance shall have the same spatial sampling and extent as the referenced image.

The Segmentation IOD does not include the full set of acquisition parameters of the referenced images, e.g., cardiac phase. An application rendering or processing the segmentation may need to access the referenced images for such information.

### A.51.2 Segmentation IOD Entity-Relationship Model

The E-R Model in Section A.1.2 depicts those components of the DICOM Information Model that directly reference the Segmentation IOD. The Segmentation is a kind of Image.

### A.51.3 Segmentation IOD Module Table

Table A.51-1. Segmentation IOD Modules

IE | Module | Reference | Usage
--- | --- | --- | ---
Patient | Patient | C.7.1.1 | M
Clinical Trial Subject | C.7.1.3 | U
Study | General Study | C.7.2.1 | M
Patient Study | C.7.2.2 | U
Clinical Trial Study | C.7.2.3 | U
Series | General Series | C.7.3.1 | M
Segmentation Series | C.8.20.1 | M
Clinical Trial Series | C.7.3.2 | U
Frame of Reference | Frame of Reference | C.7.4.1 | C - Required if Derivation Image Functional Group (C.7.16.2.6) is not present. May be present otherwise.
Equipment | General Equipment | C.7.5.1 | M
Enhanced General Equipment | C.7.5.2 | M
Segmentation | General Image | C.7.6.1 | M
Image Pixel | C.7.6.3 | M
Segmentation Image | C.8.20.2 | M
Multi-frame Functional Groups | C.7.6.16 | M
Multi-frame Dimension | C.7.6.17 | M
Specimen | C.7.6.22 | U
Common Instance Reference | C.12.2 | C - Required if Derivation Image Functional Group (C.7.16.2.6) is present.
SOP Common | C.12.1 | M
Frame Extraction | C.12.3 | C - Required if the SOP Instance was created in response to a Frame-Level retrieve request

### Note

The Specimen Identification Module was previously included in this IOD but has been retired, and its functionality replaced by the Specimen Module. See PS3.3-2008.

### A.51.4 Segmentation IOD Content Constraints

The VOI LUT module shall not be present.

The Modality LUT module shall not be present.

The Overlay Module shall not be present.

Pixel Padding Value (0028,0120) shall not be present.

### A.51.5 Segmentation Functional Groups

Table A.51-2 specifies the use of the Functional Group Macros used in the Multi-frame Functional Group Module for the Segmentation IOD.

Table A.51-2. Segmentation Functional Group Macros

Functional Group Macro | Section | Usage
--- | --- | ---
Pixel Measures | C.7.6.16.2.1 | C - Required if Derivation Image Functional Group (C.7.6.16.2.6) is not present. May be present otherwise. See Section A.51.5.1
Plane Position (Patient) | C.7.6.16.2.3 | C - Required if Derivation Image Functional Group (C.7.6.16.2.6) is not present. May be present otherwise. See Section A.51.5.1
Plane Orientation (Patient) | C.7.6.16.2.4 | C - Required if Derivation Image Functional Group (C.7.6.16.2.6) is not present. May be present otherwise. See Section A.51.5.1
Derivation Image | C.7.6.16.2.6 | C - Required if any of Pixel Measures (C.7.6.16.2.1) or Plane Position (Patient) (C.7.6.16.2.3) or Plane Orientation (Patient) (C.7.6.16.2.4) Functional Groups are not present. May be present otherwise. See Section A.51.5.1
Frame Content Macro | C.7.6.16.2.2 | M
Segmentation | C.8.20.3.1 | M

#### A.51.5.1 Segmentation Functional Groups Description

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. The Derivation Image Functional Group may also be present, to specify on which images the segmentation was actually performed (since there may be others in the same Frame of Reference that are spatially co-located, but were not used to perform the segmentation).

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. If both the Frame of Reference UID and the Derivation Image Functional Group are present, the segmentation and referenced image pixels need not correspond.

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").

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