# Question on using Scissors

**URL:** <https://discourse.slicer.org/t/question-on-using-scissors/12071>\
**Category:** Support\
**Tags:** segmentation\
**Created:** [June 17, 2020, 1:40pm UTC](https://discourse.slicer.org/t/question-on-using-scissors/12071 "2020-06-17T13:40:10Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Deepa](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/deepa/32/5634_2.png) [@Deepa](https://discourse.slicer.org/u/Deepa)\
**Post date:** [June 17, 2020, 1:40pm UTC](https://discourse.slicer.org/t/question-on-using-scissors/12071/1 "2020-06-17T13:40:10Z")

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Hello,

I have loaded 2D slices using `Image Stacks`. Before reconstructing 3D volume using these slices, I’d like to use the `Scissors` effect in `Segment Editor` to edit only the region shown in the image below (rectangle -yellow)

 ![Untitled](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/7/d/7d04f9942a6017df1c5cc2d9fc6e6a461c908bc0.png)

I 've selected `erase outside`. But the region outside the rectangle has not been erased. I’m not sure if I have missed any step.

Suggestions will be highly appreciated!

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**Author:** ![muratmaga](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/muratmaga/32/3622_2.png) [@muratmaga](https://discourse.slicer.org/u/muratmaga)\
**Post date:** [June 17, 2020, 3:00pm UTC](https://discourse.slicer.org/t/question-on-using-scissors/12071/2 "2020-06-17T15:00:06Z")

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As the name implies, `segment editor` edits segments. Your segment is blank, so there is nothing to erase from. First define segment (via threshold perhaps), then you can remove any selection with scissors tool.

If your goal is to make a smaller volume than the original, then use the `crop volume` module.

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<div class="post-metadata">

**Author:** ![Deepa](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/deepa/32/5634_2.png) [@Deepa](https://discourse.slicer.org/u/Deepa)\
**Post date:** [June 17, 2020, 3:49pm UTC](https://discourse.slicer.org/t/question-on-using-scissors/12071/3 "2020-06-17T15:49:03Z")

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> [@muratmaga](#):
>
> Your segment is blank, so there is nothing to erase from.

Thank you, I just realized that the SegmentEditorExtraEffects plugin has to be installed to use the mask volume after selecting the region using scissors.

> [@muratmaga](#):
>
> If your goal is to make a smaller volume than the original, then use the `crop volume` module.

Could you please have a look at [this](https://discourse.slicer.org/t/resampling-a-volume-and-image-spacing/12066/2) post?