C.8.8.7 RT Dose ROI Module
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#### C.8.8.7 RT Dose ROI Module

RT Dose ROI provides ancillary dose-related information to the ROI data defined within the Structure Set and ROI Contour modules, which may be included in the RT Dose IOD composite object. These modules in combination provide for the definition of dose data in the form of isodose curves or named or unnamed dose points. Isodose curves in radiation oncology are simply contours identifying a set of points with the same dose value.

Table C.8-43. RT Dose ROI Module Attributes

Attribute Name | Tag | Type | Attribute Description
--- | --- | --- | ---
RT Dose ROI Sequence | (3004,0010) | 1 | Sequence specifying dose levels for isodose curves or dose points described in the ROI module. One or more items shall be included in this sequence. See Section C.8.8.7.1.
>Referenced ROI Number | (3006,0084) | 1 | Uniquely identifies the referenced ROI within the current RT Dose. See Note 1 and Section C.8.8.7.2.
>Dose Units | (3004,0002) | 1 | Units used for ROI Dose. Enumerated Values: GY Gray RELATIVE dose relative to implicit reference value
>Dose Value | (3004,0012) | 1 | Dose value for ROI, in units defined by Dose Units (3004,0002). See Section C.8.8.7.3.

### Note

1. The Structure Set ROI Sequence (3006,0020) defining the dose point and surfaces is defined in the Structure Set module. ROI Number (3006,0022) is unique within the Structure Set ROI Sequence, and is referenced from the RT Dose ROI module using Referenced ROI Number (3006,0084).

2. The RT Dose ROI module defines the attributes that describe references to ROIs contained within the associated Structure Set and RT ROI Contour modules. Note that the RT Dose module table specifies that either all or none of the modules Structures Set, ROI Contour, and RT Dose ROI must be present in the RT Dose IOD.

##### C.8.8.7.1 Contour Geometric Type of Referenced ROI

ROIs referenced in the RT Dose ROI Module shall have a Contour Geometric Type (3006,0042) of POINT, OPEN_PLANAR or CLOSED_PLANAR.

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