The RT DVH module provides for the inclusion of differential or cumulative dose volume histogram data. The data contained within this module may supplement dose data in the RT Dose and/or RT Dose ROI modules, or it may be present in the absence of other dose data.
Table C.8-40—RT DVH MODULE ATTRIBUTES
|Attribute Name||Tag||Type||Attribute Description|
|Referenced Structure Set Sequence||(300C,0060)||1||Introduces sequence of one class/instance pair describing Structure Set containing structures which are used to calculate Dose-Volume Histograms (DVHs). Only a single item shall be included in this sequence. See C.188.8.131.52.|
|>Include ‘SOP Instance Reference Macro' Table 10-11|
|DVH Normalization Point||(3004,0040)||3||Coordinates (x, y, z) of common DVH normalization point in the patient based coordinate system described in C.184.108.40.206.1 (mm).|
|DVH Normalization Dose Value||(3004,0042)||3||Dose Value at DVH Normalization Point (3004,0040) used as reference for individual DVHs when Dose Units (3004,0002) is RELATIVE.|
|DVH Sequence||(3004,0050)||1||Introduces sequence of DVHs. One or more items shall be included in this sequence.|
|>DVH Referenced ROI Sequence||(3004,0060)||1||Introduces sequence of referenced ROIs used to calculate DVH. One or more items shall be included in this sequence.|
|>>Referenced ROI Number||(3006,0084)||1||Uniquely identifies ROI used to calculate DVH specified by ROI Number (3006,0022) in Structure Set ROI Sequence (3006,0020) in Structure Set Module within RT Structure Set referenced by referenced RT Plan in Referenced RT Plan Sequence (300C,0002) in RT Dose Module.|
|>>DVH ROI Contribution Type||(3004,0062)||1||Specifies whether volume within ROI is included or excluded in DVH. See C.220.127.116.11. Enumerated Values: INCLUDED, EXCLUDED.|
|>DVH Type||(3004,0001)||1||Type of DVH. Enumerated Values: DIFFERENTIAL = differential dose-volume histogram CUMULATIVE = cumulative dose-volume histogram NATURAL = natural dose volume histogram|
|>Dose Units||(3004,0002)||1||Dose axis units. Enumerated Values: GY = Gray RELATIVE = dose relative to reference value specified in DVH Normalization Dose Value (3004,0042)|
|>Dose Type||(3004,0004)||1||Type of dose. Defined Terms: PHYSICAL = physical dose EFFECTIVE = physical dose after correction for biological effect using user-defined modeling technique ERROR = difference between desired and planned dose|
|>DVH Dose Scaling||(3004,0052)||1||Scaling factor that when multiplied by the dose bin widths found in DVH Data (3004,0058), yields dose bin widths in the dose units as specified by Dose Units (3004,0002).|
|>DVH Volume Units||(3004,0054)||1||Volume axis units. Defined Terms: CM3 = cubic centimeters PERCENT = percent PER_U= volume per u with u(dose)=dose-3/2. See C.18.104.22.168.|
|>DVH Number of Bins||(3004,0056)||1||Number of bins n used to store DVH Data (3004,0058).|
|>DVH Data||(3004,0058)||1||A data stream describing the dose bin widths Dn and associated volumes Vn in DVH Volume Units (3004,0054) in the order D1V1, D2V2, ... DnVn. Note: DVH Data arrays may not be properly encoded if Explicit-VR transfer syntax is used and the VL of this attribute exceeds 65534 bytes.|
|>DVH Minimum Dose||(3004,0070)||3||Minimum calculated dose to ROI(s) described by DVH Referenced ROI Sequence (3004,0060).|
|>DVH Maximum Dose||(3004,0072)||3||Maximum calculated dose to ROI(s) described by DVH Referenced ROI Sequence (3004,0060).|
|>DVH Mean Dose||(3004,0074)||3||Mean calculated dose to ROI(s) described by DVH Referenced ROI Sequence (3004,0060).|
The Referenced Structure Set Sequence (300C,0060) is required for direct cross-reference of the dose bin data with the corresponding ROI(s) from which they were derived. ROIs referenced by the DVH Referenced ROI Sequence (3004,0050) shall only contain contours with a Contour Geometric Type (3006,0042) of POINT or CLOSED_PLANAR.
The volume used to calculate the DVH shall be the geometric union of ROIs where DVH ROI Contribution Type (3004,0062) is INCLUDED, minus the geometric union of ROIs where DVH ROI Contribution Type (3004,0062) is EXCLUDED.
The unit PER_U is defined in: Anderson, LL: “A “natural” volume-dose histogram for brachytherapy”, Medical Physics 13(6) pp 898-903, 1986.