DICOM PS3.3 2021c - Information Object Definitions

10.34 Conceptual Volume Segmentation Reference and Combination Macro (Current)
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## 10.34 Conceptual Volume Segmentation Reference and Combination Macro

This Macro allows the combination of Conceptual Volumes as constituents of a combined volume. A representative example is to have the Left Lung and the Right Lung segmented, and then to declare the Lungs as a combined Conceptual Volume, for which prescription constraints can be defined.

The Macro also allows reference to RT Segment Annotation SOP Instances, which contain a segmented representation of the Conceptual Volume. At the invocation of this Macro it is declared, whether this segmented representation is required or not.

Figure 10.34-1. Conceptual Volume References

Figure 10.34-1 describes an RT Physician Intent Instance where Conceptual Volumes "Lung, left" and "Lung, right" are referenced, but not defined. In this example, the RT Segmentation Annotation Instances then define the volumetric information of the Conceptual Volumes by referencing a specific segment of a Segmentation Instance and a specific ROI in an RT Structure Set Instance.

Figure 10.34-2. Conceptual Volume Combination References

Figure 10.34-1 describes an RT Physician Intent Instance defining Conceptual Volumes "Lung, left" and "Lung, right" and Conceptual Volume "Lung" as a combination of the first two without a direct reference to a volume definition.

Table 10.34-1. Conceptual Volume Segmentation Reference And Combination Macro Attributes

Attribute Name | Tag | Type | Attribute Description
--- | --- | --- | ---
Include Table 10.33-1 “Conceptual Volume Macro Attributes” |
Conceptual Volume Combination Flag | (3010,000E) | 1 | Indication that this Conceptual Volume is a combination of other Conceptual Volumes. Enumerated Values: YES NO
Conceptual Volume Constituent Sequence | (3010,0008) | 1C | References to Conceptual Volumes which are constituents of this Conceptual Volume. See Section 10.34.1.1. Required if Conceptual Volume Combination Flag (3010,000E) equals YES. One or more Items shall be included in this Sequence. The combined Conceptual Volume UID shall not be included in the Sequence.
>Conceptual Volume Constituent Index | (3010,000D) | 1 | An index referenced in the Conceptual Volume Combination Expression (3010,000C) identifying the Conceptual Volume Constituent. The value shall start at 1 and increase monotonically by 1.
>Constituent Conceptual Volume UID | (3010,0013) | 1 | UID identifying the Conceptual Volume that is a constituent of the combined Conceptual Volume.
>Originating SOP Instance Reference Sequence | (3010,0007) | 1 | Reference to the SOP Instance that contains the original definition of the Conceptual Volume constituent identified by Constituent Conceptual Volume UID (3010,0013) in this Sequence. If this Conceptual Volume originated in the current SOP Instance, then the referenced SOP Instance UID is the current SOP Instance UID. Only a single Item shall be included in this Sequence.
>>Include Table 10-11 “SOP Instance Reference Macro Attributes” |
>Conceptual Volume Constituent Segmentation Reference Sequence | (3010,0012) | 1C | Contains a segmented representation of the Conceptual Volume constituent. Required if the Conceptual Volume Segmentation Defined Flag (3010,0010) equals YES and the Conceptual Volume is not a Combination of other Conceptual Volumes. Only a single Item shall be included in this Sequence. See Section 10.34.1.2.
>>Referenced Direct Segment Instance Sequence | (3010,004A) | 1 | Reference to the SOP Instance that contains the Direct Segment Reference Sequence (3010,0023). Only a single Item shall be included in this Sequence. See Section 10.34.1.3.
>>>Include Table 10-11 “SOP Instance Reference 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 representing this Conceptual Volume. Shall reference only segment Items that contain the Direct Segment Reference Sequence (3010,0023).
Conceptual Volume Combination Expression | (3010,000C) | 1C | Symbolic expression specifying the combination of Conceptual Volumes as a text string consisting of Conceptual Volume Constituent Index (3010,000D) values, combination operators and parentheses. Required if Conceptual Volume Combination Flag (3010,000E) equals YES. See Section 10.34.1.1.
Conceptual Volume Combination Description | (3010,000F) | 2C | Human-readable description of the combination of Conceptual Volumes. This information is intended for display and shall not be used for structured processing. Required if Conceptual Volume Combination Flag (3010,000E) equals YES.
Conceptual Volume Segmentation Defined Flag | (3010,0010) | 1 | Indication that there are defined segmentations for this Conceptual Volume. Enumerated Values: YES NO
Conceptual Volume Segmentation Reference Sequence | (3010,0011) | 1C | Contains a segmented representation of the Conceptual Volume. Required when Conceptual Volume Segmentation Defined Flag (3010,0010) equals YES and Conceptual Volume Combination Flag Indicator (3010,000E) equals NO. Only a single Item shall be included in this Sequence. See Section 10.34.1.4.
>Referenced Direct Segment Instance Sequence | (3010,004A) | 1 | Reference to the SOP Instance that contains the Segment Reference Sequence (3010,0021) in which the segment is defined. Only a single Item shall be included in this Sequence. See Section 10.34.1.3.
>>Include Table 10-11 “SOP Instance Reference 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 representing this Conceptual Volume. In the segment Item referenced, the Direct Segment Reference Sequence (3010,0023) shall be present.

### 10.34.1 Conceptual Volume Segmentation Reference and Combination Macro Attribute Description

#### 10.34.1.1 Conceptual Volume Combination Expression

For Conceptual Volumes specified as a combination of other Conceptual Volumes, the combination logic is specified by the text string value of the Conceptual Volume Combination Expression (3010,000C).

A nested list notation is used to apply geometric operators to a set of Conceptual Volumes.

The first element of the list shall be one of the following geometric operators:

UNION

  geometric union of two or more arguments

INTERSECTION

  geometric intersection of two or more arguments

NEGATION

  geometric inverse of a single argument

SUBTRACTION

  geometric subtraction of second argument from the first

XOR

  geometric exclusive disjunction of two arguments

### Note

The result of a NEGATION operation is well-defined only if used as an operand to an INTERSECTION. NEGATION without context to an INTERSECTION results in an infinite Volume.

Subsequent elements shall specify arguments of the geometric operator. An argument is either a Conceptual Volume Constituent Index (3010,000D) value (i.e., positive integer) or a parenthesized list of operations.

The grammar for the Conceptual Volume Combination Expression (<sexpr>) is shown below in BNF (Backus Naur Form) :

    <sexpr>         :: <cv> | <list>
    <cv>            :: 1 | 2 | 3 | …
    <list>          :: ( <op1><sp><sexpr> ) |
                       ( <op2><sp><sexpr><sp><sexpr> ) |
                       ( <op3><sp><args> )
    <args>          :: <sexpr><sp><sexpr> | <args><sp><sexpr>
    <op1>           :: NEGATION
    <op2>           :: SUBTRACTION | XOR
    <op3>           :: UNION | INTERSECTION
    <sp>            :: 0x20

Examples:

1. Union of paired organs 1 and 2 (disjoint)

   Figure 10.34.1.1-1. Conceptual Volume Example of Union of Disjoint Volumes

   Conceptual Volume Combination Expression (3010,000C):

   (UNION 1 2)

   Items in Conceptual Volume Constituent Sequence (3010,0008):

   Table 10.34.1.1-1. Conceptual Volume Example of Union of Disjoint Volumes

   Conceptual Volume Constituent Index (3010,000D) | Conceptual Volume
   --- | ---
   1 | Right Lung
   2 | Left Lung

2. Union of paired organs 1 and 2 (non-disjoint)

   Figure 10.34.1.1-2. Conceptual Volume Example of Union of Non-disjoint Volumes

   Conceptual Volume Combination Expression (3010,000C):

   (UNION 1 2)

   Items in Conceptual Volume Constituent Sequence (3010,0008) :

   Table 10.34.1.1-2. Conceptual Volume Example of Union of non-disjoint Volumes

   Conceptual Volume Constituent Index (3010,000D) | Conceptual Volume
   --- | ---
   1 | Spinal Cord PRV
   2 | Left Lung

3. Union of two organs 1 and 2 with excluded volume 3 using NEGATION

   Figure 10.34.1.1-3. Conceptual Volume Example of Intersection and Negation

   Conceptual Volume Combination Expression (3010,000C):

   (INTERSECTION (UNION 1 2) (NEGATION 3) )

   Items in Conceptual Volume Constituent Sequence (3010,0008):

   Table 10.34.1.1-3. Conceptual Volume Example of Intersection and Negation

   Conceptual Volume Constituent Index (3010,000D) | Conceptual Volume
   --- | ---
   1 | Heart
   2 | Left Lung
   3 | CTV

4. Union of paired organs 1 and 2, with exclusion of multiple volumes 3, 4 and 5

   Figure 10.34.1.1-4. Conceptual Volume Example of Intersection and Union

   Conceptual Volume Combination Expression (3010,000C):

   (INTERSECTION (UNION 1 2) (NEGATION (UNION 3 4 5) ))

   ### Note

   This combination can be expressed alternatively as:

   (SUBTRACTION (UNION 1 2) (UNION 3 4 5) )

   Items in Conceptual Volume Constituent Sequence (3010,0008):

   Table 10.34.1.1-4. Conceptual Volume Example of Intersection and Union

   Conceptual Volume Constituent Index (3010,000D) | Conceptual Volume
   --- | ---
   1 | R Lung
   2 | L Lung
   3 | Node 1
   4 | Node 2
   5 | CTV

5. Intersection of overlapping volumes 1 and 2

   Figure 10.34.1.1-5. Conceptual Volume Example of Intersection of Non-disjunct Volumes

   Conceptual Volume Combination Expression (3010,000C):

   (INTERSECTION 1 2)

   Items in Conceptual Volume Constituent Sequence (3010,0008):

   Table 10.34.1.1-5. Conceptual Volume Example of Intersection of non-disjunct Volumes

   Conceptual Volume Constituent Index (3010,000D) | Conceptual Volume
   --- | ---
   1 | Rectum
   2 | Prostate PTV

6. Intersection of disjoint volumes 1 and 2

   Figure 10.34.1.1-6. Conceptual Volume Example of Intersection of Non-disjunct Volumes

   Conceptual Volume Combination Expression (3010,000C):

   (INTERSECTION 1 2)

   Items in Conceptual Volume Constituent Sequence (3010,0008):

   Table 10.34.1.1-6. Conceptual Volume Example of Intersection of disjunct Volumes

   Conceptual Volume Constituent Index (3010,000D) | Conceptual Volume
   --- | ---
   1 | Bladder
   2 | Prostate

#### 10.34.1.2 Conceptual Volume Segmentation Reference Sequence

The Conceptual Volume Constituent Segmentation Reference Sequence (3010,0012) contains a reference to a segmentation which represents the volume of this constituent geometrically. The referenced segmentations of the constituents of a combined Conceptual Volume may be in one or more Frames of References.

The Conceptual Volume constituents shall not include the combined Conceptual Volume being defined. Applications that wish to combine existing segmentations within the same Conceptual Volume must create a new Segmentation Instance.

#### 10.34.1.3 Referenced Direct Segment Instance Sequence

A SOP Instance may only be referenced in this Sequence if it belongs to a SOP Class that includes the Section C.36.9 Segment Reference Module.

#### 10.34.1.4 Conceptual Volume Segmentation Reference Sequence

The Conceptual Volume Segmentation Reference Sequence (3010,0011) contains a reference to a segmentation which represents this volume geometrically.

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DICOM PS3.3 2021c - Information Object Definitions