# Convert relative 3ddose to absolute dose in 3DSlicer

**URL:** https://discourse.slicer.org/t/convert-relative-3ddose-to-absolute-dose-in-3dslicer/42852
**Category:** Support
**Tags:** slicerrt, file-import
**Created:** [May 9, 2025, 1:37pm UTC](https://discourse.slicer.org/t/convert-relative-3ddose-to-absolute-dose-in-3dslicer/42852 "2025-05-09T13:37:42Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![TaHamI](https://avatars.discourse-cdn.com/v4/letter/t/67e7ee/32.png) [@TaHamI](https://discourse.slicer.org/u/TaHamI)
#### Post date: [May 9, 2025, 1:37pm UTC](https://discourse.slicer.org/t/convert-relative-3ddose-to-absolute-dose-in-3dslicer/42852/1 "2025-05-09T13:37:43Z")

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Hello,  
I know, DOSXYZnrc like other monte-carlo simulations reports relative (normalized) dose (averaging on the number of histories, the number of histories just relates to dose uncertainty, no change the dose value).  
I run DOSXYZnrc, then import the .3ddose output file into 3DSlicer and try to convert it to RT Dose. When I want to convert 3ddose to RT Dose, it takes “unit name” and “dose unit value(scaling)”. I guess, if I change the value scaling, it will change the absolute dose. But I see, when I change the value scaling, no change in absolute dose, and surprisingly, when I change the number of histories (in DOSXYZnrc simulation), I see the absolute dose changes!  
Where am I doing wrong?

Operating system: windows 10 64bit  
Slicer version: 5.8.1

Any help would be appreciated.

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<div class="post-metadata">

### Author: ![cpinter](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/cpinter/32/7995_2.png) [@cpinter](https://discourse.slicer.org/u/cpinter)
#### Post date: [May 12, 2025, 1:56pm UTC](https://discourse.slicer.org/t/convert-relative-3ddose-to-absolute-dose-in-3dslicer/42852/2 "2025-05-12T13:56:13Z")

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The dose unit scaling that you enter when converting a regular volume to RT dose volume does not get hard-applied on the image. Instead, it is considered when calculating the DVH, or when using the Dose Accumulation module. If you want to apply it, I suggest you either do a dose accumulation with this single volume, or you apply it manually. For that I’d use the Simple Filters module / ShiftScaleImageFilter.

If I didn’t answer your question then probably I misunderstood and need some more information.