# SlicerRT dose volume object
**URL:** https://discourse.slicer.org/t/slicerrt-dose-volume-object/17985
**Category:** Development
**Created:** [June 7, 2021, 1:06am UTC](https://discourse.slicer.org/t/slicerrt-dose-volume-object/17985 "2021-06-07T01:06:47Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@edwardwang1](https://discourse.slicer.org/u/edwardwang1)
#### Post date: [June 7, 2021, 1:06am UTC](https://discourse.slicer.org/t/slicerrt-dose-volume-object/17985/1 "2021-06-07T01:06:47Z")
Hi there,
I am doing some work where I am creating radiation dose distributions for simulated tumours from scratch (rather than exporting from a RT planning software). In Python I generate a 3D numpy array which I convert to a _vtkMRMLScalarVolumeNode_. How do I convert my scalar volume node into a dose volume node that is used by the Dose Volume Histogram module in SlicerRT?
I am able to successfully load in dose volumes from DICOM data. When I investigate those volumes, I find that they are also _vtkMRMLScalarVolumeNodes_. What differentiates a dose volume node from other Scalar Volume Nodes (besides the unit).
Thank you,
Ed
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### Author:  [@lassoan](https://discourse.slicer.org/u/lassoan)
#### Post date: [June 7, 2021, 4:03am UTC](https://discourse.slicer.org/t/slicerrt-dose-volume-object/17985/2 "2021-06-07T04:03:37Z")
Yes, it is mainly about setting the unit, but you also need to have the dose volume under a proper DICOM hierarchy. You can find all the necessary steps in the implementation of the right-click menu action (in Data module) that converts a regular volume to a dose volume:
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### Author:  [@edwardwang1](https://discourse.slicer.org/u/edwardwang1)
#### Post date: [June 7, 2021, 4:47pm UTC](https://discourse.slicer.org/t/slicerrt-dose-volume-object/17985/3 "2021-06-07T16:47:05Z")
Thank you, this is exactly what I was looking for!
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### Author:  [@edwardwang1](https://discourse.slicer.org/u/edwardwang1)
#### Post date: [June 7, 2021, 6:40pm UTC](https://discourse.slicer.org/t/slicerrt-dose-volume-object/17985/4 "2021-06-07T18:40:26Z")
In case this is useful for others, here is my Python code to achieve this:
```auto
sh = slicer.util.getNodesByClass("vtkMRMLSubjectHierarchyNode")[0]
itemID = sh.GetItemByDataNode(MmNode)
sh.SetItemParent(itemID, sh.GetItemParent(sh.GetItemByDataNode(volumeNode)))
sh.SetItemAttribute(itemID, 'DoseUnitName', "Gy")
sh.SetItemAttribute(itemID, 'DoseUnitValue', "1.0")
MmNode.SetAttribute("DicomRtImport.DoseVolume", "1")
sh.RequestOwnerPluginSearch(itemID)
sh.ItemModified(itemID)
```