DICOM PS3.3 2021d - Information Object Definitions

C.18.6 Spatial Coordinates Macro (Current)
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### C.18.6 Spatial Coordinates Macro

Table C.18.6-1 specifies the Attributes that convey Spatial Coordinates in an SCOORD Content Item. An SCOORD Content Item shall always be the Source Content Item of one or more SELECTED FROM Relationships with IMAGE Target Content Items. Each IMAGE Target Content Item shall contain a reference to one single-frame or multi-frame Image.

### Note

The same set of spatial coordinates may be selected from more than one single-frame image, or more than one frame of a multi-frame image when the purpose of reference is applicable to multiple images. For example, the spatial coordinates may specify the outline of a sampling region at the same spatial location on multiple images acquired over time.

Table C.18.6-1. Spatial Coordinates Macro Attributes

Attribute Name | Tag | Type | Attribute Description
--- | --- | --- | ---
Graphic Data | (0070,0022) | 1 | An ordered set of (column,row) pairs that denote positions in an image specified with sub-pixel resolution such that the origin at the TLHC of the TLHC pixel is 0.0\0.0, the BRHC of the TLHC pixel is 1.0\1.0, and the BRHC of the BRHC pixel is Columns\Rows. The values must be within the range 0\0 to Columns\Rows. The maximum values are those contained in the referenced image in Attributes Columns (0028,0011) and Rows (0028,0010), or in the case of spatial coordinates with Pixel Origin Interpretation (0048,0301) value VOLUME, in Attributes Total Pixel Matrix Columns (0048,0006) and Total Pixel Matrix Rows (0048,0007). See Section C.18.6.1.1 for further explanation.
Graphic Type | (0070,0023) | 1 | See Section C.18.6.1.2 for Enumerated Values.
Pixel Origin Interpretation | (0048,0301) | 1C | For a referenced multi-frame image, specifies whether the Graphic Data (0070,0022) values are to be interpreted relative to the individual frame pixel origins, or relative to the Total Pixel Matrix origin (see Section C.8.12.4.1.4). Required if the value of Referenced SOP Class UID (0008,1150) of the referenced image is 1.2.840.10008.5.1.4.1.1.77.1.6 (VL Whole Slide Microscopy Image). May be present otherwise. Enumerated Values: FRAME relative to individual frame VOLUME relative to Total Image Matrix If not present, Graphic Data values are defined relative to the frame pixel origin.
Fiducial UID | (0070,031A) | 3 | The globally unique identifier for this fiducial Item. ### Note The fiducial UID can be used to associate this set of graphics with other Content Items.

#### C.18.6.1 Spatial Coordinates Macro Attribute Descriptions

##### C.18.6.1.1 Graphic Data

Graphic Data may be used to associate an anatomic or spatial Concept with a defined subset of one or more images. Graphic Data may be explicitly defined as a single point (i.e., to denote the epicenter of an anatomic site or lesion) or more than one point (i.e., representing a set of points or an open or closed polygon).

### Note

Spatial coordinates may be used to associate observational data with a set of Image features. Spatial coordinates also may be used to convey coordinates that are input data for a measurement.

##### C.18.6.1.2 Graphic Type

When annotation applies to an image, this Attribute defines the type of geometry of the annotated region of interest.

Enumerated Values:

POINT

  a single pixel denoted by a single (column,row) pair

MULTIPOINT

  multiple pixels each denoted by an (column,row) pair

POLYLINE

  a series of connected line segments with ordered vertices denoted by (column,row) pairs; if the first and last vertices are the same it is a closed polygon

CIRCLE

  a circle defined by two (column,row) pairs. The first point is the central pixel. The second point is a pixel on the perimeter of the circle.

ELLIPSE

  an ellipse defined by four pixel (column,row) pairs, the first two points specifying the endpoints of the major axis and the second two points specifying the endpoints of the minor axis of an ellipse

### Note

1. The order of encoding of successive points for any particular Graphic Type is significant, but its meaning is not specified. The meaning of the order may be defined by a particular Template that uses them. For example, a closed POLYLINE may be encoded with a clockwise (right) or counter-clockwise (left) winding order (when viewed from a specified direction). A two-point POLYLINE used to encode a vector with a direction might be expected to originate at the first encoded point and be directed towards the second encoded point, but that is not specified.

2. A Polygon encoded as a POLYLINE is not restricted to being a simple polygon, unless so specified by the Template that uses it.

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DICOM PS3.3 2021d - Information Object Definitions