# Create DRR of a STL file

**URL:** <https://discourse.slicer.org/t/create-drr-of-a-stl-file/40186>\
**Category:** Support\
**Created:** [November 13, 2024, 9:55pm UTC](https://discourse.slicer.org/t/create-drr-of-a-stl-file/40186 "2024-11-13T21:55:44Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![phantom\_gen](https://avatars.discourse-cdn.com/v4/letter/p/e495f1/32.png) [@phantom\_gen](https://discourse.slicer.org/u/phantom_gen)\
**Post date:** [November 13, 2024, 9:55pm UTC](https://discourse.slicer.org/t/create-drr-of-a-stl-file/40186/1 "2024-11-13T21:55:44Z")

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Hi guys!

I have a STL Design, which I voxelized with a python script into a .nrrd, and assigned density +attenuation coefficients to filled and non filled voxels. How can I use this now to create a DRR like projection? I want to simulate a Mammography with about 28 keV and looked up the attenuation coefficients for my tissue of interest and fat, aswell as the respective densities. I loaded the .nrrd file into 3D slicer as a volume. How shall I proceed from here?

Here is the link of a similiar post I found about this topic and an image of my “simple projection” of the STL file:

> [@Digitally Reconstructed Radiograph Using Models Instead of Volumes](https://discourse.slicer.org/t/digitally-reconstructed-radiograph-using-models-instead-of-volumes/3309/7):
>
> Hi Guys! Although this is an older topic I thought I give it a try since I have a similiar question: The uploaded picture is an orthographic projection of a STL Design I did, which shall mimic a female breast parenchym in Mammography. I created the projection using an orthographic projection script in python. So much for the introduction, now here is my problem: I want to use 3D slicer to create a more advanced orthographic projection, like a DRR. I have voxeli…

Thank you for your help!