# Mask volume with another preset

**URL:** <https://discourse.slicer.org/t/mask-volume-with-another-preset/29796>\
**Category:** Support\
**Tags:** segmentation\
**Created:** [June 2, 2023, 10:29am UTC](https://discourse.slicer.org/t/mask-volume-with-another-preset/29796 "2023-06-02T10:29:57Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![dbtruong](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/dbtruong/32/65581_2.png) [@dbtruong](https://discourse.slicer.org/u/dbtruong)\
**Post date:** [June 2, 2023, 10:29am UTC](https://discourse.slicer.org/t/mask-volume-with-another-preset/29796/1 "2023-06-02T10:29:58Z")

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Hello All, I am trying to use mask volume with CT-Muscle preset. Why is the result below?

 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/5/e/5e541e04e469e5b6b7e175f07db3b7c46057ee09.jpeg)  
Thanks.

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [June 2, 2023, 2:45pm UTC](https://discourse.slicer.org/t/mask-volume-with-another-preset/29796/2 "2023-06-02T14:45:40Z")

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It seems that you filled the volume with value = 0. In clinical CT images the voxel values are in HU, therefore you filled the image with water/soft tissue. You may want to use -1000 to fill with air instead.

Choosing the same volume for input and output is risky, as you cannot undo your changes. I would recommend to load the input volume again (so that you restore the masked parts) and create a new output volume and use volume rendering on the masked volume.

You can follow the steps of this tutorial:

[![](https://img.youtube.com/vi/xZwyW6SaoM4/maxresdefault.jpg "New "Surface cut" and "Mask volume" tools for 3D Slicer segment editor") ](https://www.youtube.com/watch?v=xZwyW6SaoM4)

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<div class="post-metadata">

**Author:** ![dbtruong](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/dbtruong/32/65581_2.png) [@dbtruong](https://discourse.slicer.org/u/dbtruong)\
**Post date:** [June 2, 2023, 3:15pm UTC](https://discourse.slicer.org/t/mask-volume-with-another-preset/29796/3 "2023-06-02T15:15:13Z")

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@lassoan Thanks a lot for your explanation and advice