DICOM PS3.3 2021b - Information Object Definitions

C.36.8 RT Segment Annotation Module (Current)
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### C.36.8 RT Segment Annotation Module

The RT Segment Annotation Module references segments and provides radiotherapy-specific annotations for them. The geometry of each segment is defined by a referenced Segmentation, Surface Segmentation, RT Structure Set or any other general-purpose Instance that represents geometric information.

The values of the following Attribute shall take precedence over values in the referenced SOP Instances:

- Segment Annotation Category Code Sequence (3010,002B)

- Segment Annotation Type Code Sequence (3010,002C)

Table C.36.8-1. RT Segment Annotation Module Attributes

Attribute Name | Tag | Type | Attribute Description
--- | --- | --- | ---
Include Table 10.9.2-1 “Extended Content Identification Macro Attributes” | The Content Creator's Name (0070,0084) shall be the name of the most recent person to significantly modify the content of this SOP Instance.
RT Segment Annotation Sequence | (3010,002A) | 1 | Annotations for segments are described in this Sequence. One or more Items shall be included in this Sequence.
>RT Segment Annotation Index | (3010,003D) | 1 | Index of the Segment. The value shall start at 1 and increase monotonically by 1.
>Include Table 10.32-1 “Entity Long Labeling Macro Attributes” |
>Referenced Segment Reference Index | (3010,0020) | 1 | The Segment Reference Index (3010,0022) in the Segment Reference Sequence (3010,0021) corresponding to the segment this Sequence Item relates to.
>Segment Annotation Category Code Sequence | (3010,002B) | 2 | Category of the annotation of this segment. Zero or one Item shall be included in this Sequence.
>>Include Table 8.8-1 “Code Sequence Macro Attributes” | DCID 9502 “RT Segment Annotation Categories”.
>Segment Annotation Type Code Sequence | (3010,002C) | 1C | Specific type of the annotation of this segment. Required if Segment Annotation Category Code Sequence (3010,002B) has a value. Only a single Item shall be included in this Sequence. See Section C.36.8.1.1.
>>Include Table 8.8-1 “Code Sequence Macro Attributes” | Context Groups are specified in Section C.36.8.1.1.
>>Segment Annotation Type Modifier Code Sequence | (3010,002F) | 3 | Modifier of the type of the annotation of this segment. One or more Items are permitted in this Sequence.
>>>Include Table 8.8-1 “Code Sequence Macro Attributes” | DCID 244 “Laterality”
>Segmentation Creation Template Label | (3010,001E) | 3 | Label for the template used to define the set of segments to be created from patient images and the names, codes, default presentation parameters associated with those segments.
>Segmented RT Accessory Device Sequence | (3010,0026) | 2 | RT accessory device identification information. Zero or more Items shall be included in this Sequence. See Section C.36.8.1.2.
>>Device Index | (3010,0039) | 1 | Index of the Device. The value shall start at 1 and increase monotonically by 1.
>>Include Table 10.35-1 “Device Model Macro Attributes” |
>>Include Table 10.36-1 “Device Identification Macro Attributes” | DCID 9520 “Segmented RT Accessory Devices” .
>Segment Characteristics Precedence | (3010,0029) | 2 | Value used to resolve usage of characteristic of overlapping regions of Conceptual Volumes. In overlapping regions, the characteristic of the Conceptual Volume with the lowest number has precedence. Any number takes precedence over an empty value. The effect of precedence on the use of the characteristics is not defined in the Standard. Non-empty values shall be unique within all Items of this Sequence.
>Segment Characteristics Sequence | (3010,0027) | 3 | Characteristics associated with the current segment. One or more Items are permitted in this Sequence.
>>Include Table 10.2.1-1 “Content Item with Modifiers Macro Attributes” | DTID 15301 “RT Segment Characteristics”
>Recommended Display Grayscale Value | (0062,000C) | 3 | A default single gray unsigned value in which it is recommended that the maximum pixel value in this surface be rendered on a monochrome display. The units are specified in P-Values from a minimum of 0000H (black) up to a maximum of FFFFH (white). ### Note The maximum P-Value for this Attribute may be different from the maximum P-Value from the output of the Presentation LUT, which may be less than 16 bits in depth.
>Recommended Display CIELab Value | (0062,000D) | 3 | A default triplet value in which it is recommended that the surface be rendered on a color display. The units are specified in PCS-Values, and the value is encoded as CIELab.
>Recommended Presentation Opacity | (0066,000C) | 3 | Specifies the opacity in which it is recommended that the surface be rendered. See Section C.27.1.1.3.
>Recommended Presentation Type | (0066,000D) | 3 | Specifies the representation type in which it is recommended that the surface be rendered. See Section C.27.1.1.3.

#### C.36.8.1 RT Segment Annotation Attribute Descriptions

##### C.36.8.1.1 RT Segment Annotation Type Code Sequence

In Table C.36.8-2, if the Segment Annotation Category Code Sequence (3010,002B) has the code value specified in the left column, the Context Group for Segment Annotation Type Code Sequence (3010,002C) shall be the one specified in the right column.

Table C.36.8-2. RT Segment Annotation Type CIDs

Code Value of Segment Annotation Category Code Sequence (3010,002B) | Context Group for Segment Annotation Type Code Sequence (3010,002C)
--- | ---
(130041, DCM, "RT Target") | DCID 9534 “Radiotherapy Targets”
(130042, DCM, "RT Dose Calculation Structure") | DCID 9535 “Radiotherapy Dose Calculation Roles”
(130043, DCM, "RT Geometric Information") | DCID 9504 “RT Geometric Information”
(130047, DCM, "External Body Model") | DCID 9507 “External Body Models”
(130405, DCM, "Patient-Attached Dose Control Object") | DCID 9516 “Radiotherapy Bolus Device Types”
(130044, DCM, "Fixation or Positioning Device") | DCID 9505 “Fixation or Positioning Devices”
(130045, DCM, "Brachytherapy Device") | DCID 9506 “Brachytherapy Devices”
(130046, DCM, "Non-specific Volume") | DCID 9508 “Non-specific Volumes”

For code values in Segment Annotation Category Code Sequence (3010,002B) that are not present in Table C.36.8-2, Segment Annotation Type Code Sequence (3010,002C) BCID 7150 “Segmentation Property Categories” may be used where applicable.

##### C.36.8.1.2 Segmented RT Accessory Device Sequence

RT accessory device identification information when this segment represents a device.

### Note

For an RT accessory device, typically the Segmented Property Category Code Sequence (0062,0003) has one of the following values:

- (130044, DCM, "Fixation or Positioning Device")

- (130045, DCM, "Brachytherapy Device")

- (260787004, SCT, "Physical Object")

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DICOM PS3.3 2021b - Information Object Definitions