DICOM PS3.3 2019c - Information Object Definitions

10.27 Reference Location Macro

This Macro allows a reference location in the context of a Patient or scan to be identified and described. E.g., the Macro may describe an anatomically defined location along the axis of a CT scan to prescribe the extent of a scan or reconstruction. The location might be internal to the Patient (and appear on a localizer image) or might be an external landmark (on which a laser is aligned).

Table 10.27-1. Reference Location Macro Attributes

Attribute Name

Tag

Type

Attribute Description

Reference Location Label

(0018,9900)

1

Brief user-readable label for the location.

Reference Location Description

(0018,9901)

3

Further elaboration of the Reference Location.

The value may include a description of the relative anatomical location, the appearance of the feature or landmark, or how it can be identified.

Reference Basis Code Sequence

(0018,9902)

1

The anatomical feature or point of reference on which the reference location is based.

Only a single Item shall be included in this Sequence.

>Include Table 8.8-1 “Code Sequence Macro Attributes”

CID may be defined in the Macro invocation.

Reference Geometry Code Sequence

(0018,9903)

1

Characterizes the geometry of the reference location (e.g., a plane or point).

Only a single Item shall be included in this Sequence.

>Include Table 8.8-1 “Code Sequence Macro Attributes”

CID may be defined in the Macro invocation.

Offset Distance

(0018,9904)

3

Positive offset (in mm) from the Reference Basis to the actual Reference Location.

See Section 10.27.1.

Offset Direction

(0018,9905)

1C

Direction of the offset (in terms of patient position) from the Reference Basis to the Reference Location.

Enumerated Values:

SUPERIOR

INFERIOR

ANTERIOR

POSTERIOR

LEFT

RIGHT

PROXIMAL

DISTAL

MEDIAL

LATERAL

Required if Offset Distance (0018,9904) is present.


10.27.1 Offset Distance and Direction

An example of the use of offsets might be:

Reference Location Label

(0018,9900)

"1cm above Liver"

Reference Location Description

(0018,9901)

"1cm above the uppermost extent of the liver"

Reference Basis Code Sequence

(0018,9902)

(10200004, SCT, "Liver")

Reference Geometry Code Sequence

(0018,9903)

(128120, DCM, "Plane through Superior Extent")

Offset Distance

(0018,9904)

10

Offset Direction

(0018,9905)

SUPERIOR

DICOM PS3.3 2019c - Information Object Definitions