DICOM PS3.3 2020d - Information Object Definitions

C.18.9 3D Spatial Coordinates Macro (Current)
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### C.18.9 3D Spatial Coordinates Macro

Table C.18.9-1 specifies the Attributes that convey 3D Spatial Coordinates in an SCOORD3D Content Item.

Table C.18.9-1. 3D Spatial Coordinates Macro Attributes

Attribute Name | Tag | Type | Attribute Description
--- | --- | --- | ---
Referenced Frame of Reference UID | (3006,0024) | 1 | Uniquely identifies the Frame of Reference within which the coordinates are defined. ### Note There is no requirement that the Frame of Reference be the same for all SCOORD3D Content Items in the same SR SOP Instance, nor is there any requirement that the Frame of Reference Module be present. The Frame of Reference may be any type of DICOM Reference Coordinate System, whether it be patient-relative (Patient Based Coordinate System), volume-relative (including acquired and presentation state volumes), or whole slide relative (Slide Coordinate System).
Graphic Data | (0070,0022) | 1 | An ordered set of (x,y,z) triplets (in mm and may be negative) that define a region of interest in the patient-relative Reference Coordinate System defined by Referenced Frame of Reference UID (3006,0024). See Reference Coordinate System (RCS). See Section C.18.9.1.1 for further explanation.
Graphic Type | (0070,0023) | 1 | See Section C.18.9.1.2 for Enumerated Values.
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.18.9.1 3D Spatial Coordinates Macro Attribute Descriptions

##### C.18.9.1.1 Graphic Data

Graphic Data may be used to associate an anatomic or spatial Concept with a defined set of patient relative 3D locations in a defined Frame of Reference, independent of any image. Graphic Data may be defined explicitly 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).

##### C.18.9.1.2 Graphic Type

This Attribute defines the type of geometry of the region of interest.

Enumerated Values:

POINT

  a single location denoted by a single (x,y,z) triplet

MULTIPOINT

  multiple locations each denoted by an (x,y,z) triplet; the points need not be coplanar

POLYLINE

  a series of connected line segments with ordered vertices denoted by (x,y,z) triplets; the points need not be coplanar

POLYGON

  a series of connected line segments with ordered vertices denoted by (x,y,z) triplets, where the first and last vertices shall be the same forming a polygon; the points shall be coplanar

ELLIPSE

  an ellipse defined by four (x,y,z) triplets, the first two triplets specifying the endpoints of the major axis and the second two triplets specifying the endpoints of the minor axis

ELLIPSOID

  a three-dimensional geometric surface whose plane sections are either ellipses or circles and contains three intersecting orthogonal axes, "a", "b", and "c"; the ellipsoid is defined by six (x,y,z) triplets, the first and second triplets specifying the endpoints of axis "a", the third and fourth triplets specifying the endpoints of axis "b", and the fifth and sixth triplets specifying the endpoints of axis "c"

### Note

1. A circle is a special case of ELLIPSE where the major and minor axis points are equidistant from the center.

2. Coplanar is in the mathematical sense and is not necessarily related to a specific Image Instance.

3. 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 POLYGON 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.

4. A POLYGON is not restricted to being a simple polygon, unless so specified by the Template that uses it.

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DICOM PS3.3 2020d - Information Object Definitions