# Segmentations in segment editor isolated to one axial CT slice

**URL:** <https://discourse.slicer.org/t/segmentations-in-segment-editor-isolated-to-one-axial-ct-slice/41945>\
**Category:** Support\
**Created:** [March 3, 2025, 6:24pm UTC](https://discourse.slicer.org/t/segmentations-in-segment-editor-isolated-to-one-axial-ct-slice/41945 "2025-03-03T18:24:08Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Camilla\_Nielsen](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/camilla_nielsen/32/79606_2.png) [@Camilla\_Nielsen](https://discourse.slicer.org/u/Camilla_Nielsen)\
**Post date:** [March 3, 2025, 6:24pm UTC](https://discourse.slicer.org/t/segmentations-in-segment-editor-isolated-to-one-axial-ct-slice/41945/1 "2025-03-03T18:24:08Z")

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Operating system: Windows  
Slicer version: 5.8.0

I hope someone can help.

I need to make a segmentation on two different CT scans on only one axial slice, but when I make the first segmentation using “segment editor” a shaded segmentation is automatically created on the slice below and above. I can’t remove them using the scissor or Island tools - it just removes the segmentation completly.

How do I make a segmentation on just one axial slice? I am not an expirienced user, so maybe it is an easy solve.

Thanks

 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/e/a/ea377d12dfa508588afaa7acb11f96c69a8bf1ff.png)  
 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/e/7/e7744a8c6103543942a1f4f60d32432f40a61128.png)

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<div class="post-metadata">

**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:** [March 3, 2025, 6:28pm UTC](https://discourse.slicer.org/t/segmentations-in-segment-editor-isolated-to-one-axial-ct-slice/41945/2 "2025-03-03T18:28:31Z")

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The segmentation geometry (origin, spacing, axis directions, extents) are set when you _first_ select a source volume. It seems that rhe first volume you selected had thicker slices, so the segmentation has thicker slices, which shows up on several slices of your second volume.

You can use the “Specify geometry” button to change the segmentation geometry to match your second volume (or create a new segmentation and choose the second volume as source volume).

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**Author:** ![Camilla\_Nielsen](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/camilla_nielsen/32/79606_2.png) [@Camilla\_Nielsen](https://discourse.slicer.org/u/Camilla_Nielsen)\
**Post date:** [March 4, 2025, 7:52am UTC](https://discourse.slicer.org/t/segmentations-in-segment-editor-isolated-to-one-axial-ct-slice/41945/3 "2025-03-04T07:52:18Z")

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That did the trick. Thank you