DICOM PS3.3 2024c - Information Object Definitions
C.8.8.6 ROI Contour Module (Current)
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PS3.3 > Information Module Definitions (Normative) > Modality Specific Modules > Radiotherapy Modules > ROI Contour Module

C.8.8.6 ROI Contour Module

In general, a ROI can be defined by either a sequence of overlays or a sequence of contours. This Module, if present, is used to define the ROI as a set of contours. Each ROI contains a sequence of one or more contours, where a contour is either a single point (for a point ROI) or more than one point (representing an open or closed polygon).

Table C.8-42. ROI Contour Module Attributes

Attribute Name

Tag

Type

Attribute Description

ROI Contour Sequence

(3006,0039)

1

Sequence of Contour Sequences defining ROIs.

One or more Items shall be included in this Sequence.

>Referenced ROI Number

(3006,0084)

1

Uniquely identifies the referenced ROI described in the Structure Set ROI Sequence (3006,0020).

>ROI Display Color

(3006,002A)

3

RGB triplet color representation for ROI, specified using the range 0-255.

>Recommended Display Grayscale Value

(0062,000C)

3

A default single gray unsigned value in which it is recommended that the contour 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 contour be rendered on a color display. The units are specified in PCS-Values, and the value is encoded as CIELab. See Section C.10.7.1.1.

>Source Pixel Planes Characteristics Sequence

(3006,004A)

3

The characteristics of the pixel planes from which the grid-based representation of the Contours was derived.

Only a single Item is permitted in this Sequence.

See Section C.8.8.6.4.

Note

This is not useful if Contour Geometric Type (3006,0042) equals POINT, OPEN_PLANAR or OPEN_NONPLANAR

>>Pixel Spacing

(0028,0030)

1

Physical distance in the patient between the center of each pixel, specified by a numeric pair - adjacent row spacing (delimiter) adjacent column spacing in mm. See Section 10.7.1.3 for further explanation.

>>Spacing Between Slices

(0018,0088)

1

Spacing between adjacent slices, in mm. The spacing is measured from the center-to-center of each slice, and shall not be negative.

>>Image Orientation (Patient)

(0020,0037)

1

The direction cosines of the first row and the first column with respect to the patient. See Section C.7.6.2.1.1.

>>Image Position (Patient)

(0020,0032)

1

The x, y and z coordinates in mm of the upper left hand corner of the pixel matrix in the Patient-Based Coordinate System described in Section C.7.6.2.1.1.

>>Number of Frames

(0028,0008)

1

Number of source pixel planes.

>>Rows

(0028,0010)

1

Number of rows in the source pixel planes.

>>Columns

(0028,0011)

1

Number of columns in the source pixel planes.

>Source Series Sequence

(3006,004B)

3

Identifies the Image Series on which the ROI was defined.

One or more Items are permitted in this Sequence.

Note

  1. The referenced Series may or may not have the same Frame of Reference UID (0020,0052) as this Instance, and there may be more than one referenced Series within the same Frame of Reference UID (0020,0052).

  2. The referenced Series may or may not contain the images referenced in the Contour Image Sequence (3006,0016).

>>Series Instance UID

(0020,000E)

1

Unique identifier of the Series containing the referenced Instances.

>Contour Sequence

(3006,0040)

3

Sequence of Contours defining ROI. One or more Items are permitted in this Sequence.

>>Contour Number

(3006,0048)

3

Identification number of the contour. The value of Contour Number (3006,0048) shall be unique within the Contour Sequence (3006,0040) in which it is defined. No semantics or ordering shall be inferred from this Attribute.

>>Contour Image Sequence

(3006,0016)

3

Sequence of images containing the contour.

One or more Items are permitted in this Sequence.

See Section C.8.8.6.4.

>>>Include Table 10-3 “Image SOP Instance Reference Macro Attributes”

>>Contour Geometric Type

(3006,0042)

1

Geometric type of contour. See Section C.8.8.6.1.

Enumerated Values:

POINT

single point

OPEN_PLANAR

open contour containing coplanar points

OPEN_NONPLANAR

open contour containing non-coplanar points

CLOSED_PLANAR

closed contour (polygon) containing coplanar points

CLOSEDPLANAR_XOR

closed contour (polygon) containing coplanar points of an inner or outer contour combined using an XOR operator

>>Number of Contour Points

(3006,0046)

1

Number of points (triplets) in Contour Data (3006,0050).

>>Contour Data

(3006,0050)

1

Sequence of (x,y,z) triplets defining a contour in the Patient-Based Coordinate System described in Section C.7.6.2.1.1 (mm). See Section C.8.8.6.1 and Section C.8.8.6.3.

See Section C.8.8.6.4.

Note

Contour Data may not be properly encoded if Explicit VR Transfer Syntax is used and the VL of this Attribute exceeds 65534 bytes.

C.8.8.6.1 Contour Geometric Type

A contour can be one of the following geometric types:

  • A Contour Geometric Type (3006,0042) of POINT indicates that the contour is a single point, defining a specific location of significance.

  • A Contour Geometric Type (3006,0042) of OPEN_PLANAR indicates that the last vertex shall not be connected to the first point, and that all points in Contour Data (3006,0050) shall be coplanar.

  • A Contour Geometric Type (3006,0042) of OPEN_NONPLANAR indicates that the last vertex shall not be connected to the first point, and that the points in Contour Data (3006,0050) may be non-coplanar. Contours having a Geometric Type (3006,0042) of OPEN_NONPLANAR can be used to represent objects best described by a single, possibly non-coplanar curve, such as a brachytherapy applicator.

  • A Contour Geometric Type (3006,0042) of CLOSED_PLANAR indicates that the last point shall be connected to the first point, where the first point is not repeated in Contour Data (3006,0050). All points in Contour Data (3006,0050) shall be coplanar.

  • A Contour Geometric Type (3006,0042) of CLOSEDPLANAR_XOR indicates that the last point shall be connected to the first point, where the first is not repeated in Contour Data (3006,0050). All points in Contour Data (3006,0050) shall be coplanar. More than one Contour is used to describe an ROI and these Contours are combined by geometric exclusive disjunction, see Section C.8.8.6.3. If any of the Contours within an ROI is of Contour Geometric Type (3006,0042) CLOSEDPLANAR_XOR, all Contours of that ROI shall be of the same type.

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DICOM PS3.3 2024c - Information Object Definitions