DICOM PS3.3 2020d - Information Object Definitions
C.36.2.2.9 RT Beam Limiting Device Opening Macro

This Macro defines the opening created by RT Beam Limiting Devices at a specific Control Point or set of Control Points.

Table C.36.2.2.9-1. RT Beam Limiting Device Opening Macro Attributes

Attribute Name

Tag

Type

Attribute Description

Number of RT Beam Limiting Device Openings

(300A,0657)

1C

Number of RT Beam Limiting Device Openings in the RT Beam Limiting Device Opening Sequence (300A,0656).

Required if Number of RT Beam Limiting Devices (300A,0641) is present and has a non-zero value.

RT Beam Limiting Device Opening Sequence

(300A,0656)

1C

Beam limiting device (collimator) settings defining the opening for the current Control Point.

Required if Number of RT Beam Limiting Device Openings (300A,0657) is present and has a non-zero value and the conditions in Section C.36.2.2.5.1.1 are satisfied.

The number of Items included in this Sequence shall equal the value of Number of RT Beam Limiting Device Openings (300A,0657).

>Referenced Device Index

(300A,0607)

1

The value of Device Index (3010,0039) from the RT Beam Limiting Device Definition Sequence (300A,064D) corresponding to the Beam Limiting Device used in this Item.

>RT Beam Limiting Device Offset

(300A,064B)

1C

The offsets (x,y) in mm of the Parallel RT Beam Delimiter Positions (300A,064A) from the central beam axis.

See Section C.36.2.2.9.1.1 and Section C.36.2.2.8.1.2.

Required if the conditions in Section C.36.2.2.5.1.1 are satisfied.

>Parallel RT Beam Delimiter Positions

(300A,064A)

1C

One-dimensional positions of the tip in mm of beam delimiters.

If Device Type Code Sequence (3010,002E) contains (130333, DCM, "Single Leaves"), N values shall be provided where N is the Number of Parallel RT Beam Delimiters (300A,0648).

If Device Type Code Sequence contains (130330, DCM, "Jaw Pair") or (130331, DCM, "Leaf Pairs"), 2N values shall be provided where N is the Number of Parallel RT Beam Delimiters (300A,0648). The values shall be grouped by the mounting side identified by the Parallel RT Beam Delimiter Leaf Mounting Side (300A,064F) with the values of RT Beam Delimiter Elements on the negative mounting side first.

The order of values shall correspond to the order of the Parallel RT Beam Delimiter Boundaries (300A,0649).

See Section C.36.2.2.9.1.1, Section C.36.2.2.9.1.2 and Section C.36.2.2.9.1.3.

Required if the conditions in Section C.36.2.2.5.1.1 are satisfied and if Device Type Code Sequence contains (130330, DCM, "Jaw Pair"), (130331, DCM, "Leaf Pairs") or (130333, DCM, "Single Leaves").

>RT Beam Delimiter Geometry Sequence

(300A,064C)

1C

The outline of the Beam Limiting Device opening.

Required if the conditions in Section C.36.2.2.5.1.1 are satisfied and if DeviceType Code Sequence (3010,002E) contains (130332, DCM, "Variable Circular Collimator").

See Section C.36.2.2.9.1.1 and Section C.36.2.2.9.1.3.

Only a single Item shall be included in this Sequence.

>>Include Table 10.38-1 “Outline Definition Macro Attributes”.

The Outline Shape Type (0018,1630) shall be CIRCULAR.

The plane is defined in Section C.36.2.2.9.1.1.


C.36.2.2.9.1 RT Beam Limiting Device Opening Attribute Descriptions
C.36.2.2.9.1.1 Geometric Value Attributes

All geometric values in Table C.36.2.2.9-1 are defined in the Beam Modifier Definition Plane.

C.36.2.2.9.1.2 RT Beam Delimiter Element Positions

For Device Type Code Sequence (3010,002E) values of (130330, DCM, "Jaw Pair") or (130331, DCM, "Leaf Pairs"), the order of values are

N1, N2, Nn

P1, P2, Pn

where N denotes the negative mounting side, P the positive mounting side and the indices increasing corresponding to the order of the values of Parallel RT Beam Delimiter Boundaries (300A,0649).

C.36.2.2.9.1.3 RT Beam Delimiter Geometry

The definition of the tip positions in Parallel RT Beam Delimiter Positions (300A,064A) or delimiter outline in the RT Beam Delimiter Geometry Sequence (300A,064C) is as defined by the manufacturer and shall be documented in the Conformance Statement. Typically, this will be the radiological or physical edge.

DICOM PS3.3 2020d - Information Object Definitions