# Elastix Registration 3D CT monomodal lung

**URL:** <https://discourse.slicer.org/t/elastix-registration-3d-ct-monomodal-lung/34394>\
**Category:** Support\
**Tags:** elastix, lung\
**Created:** [February 19, 2024, 11:59am UTC](https://discourse.slicer.org/t/elastix-registration-3d-ct-monomodal-lung/34394 "2024-02-19T11:59:52Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Alice\_Durante](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/alice_durante/32/67737_2.png) [@Alice\_Durante](https://discourse.slicer.org/u/Alice_Durante)\
**Post date:** [February 19, 2024, 11:59am UTC](https://discourse.slicer.org/t/elastix-registration-3d-ct-monomodal-lung/34394/1 "2024-02-19T11:59:52Z")

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Hello to all  
I’ve been using the toolbox “registration” of 3d Slicer, especially “elastix”. Trying with a registration with “generic (all)” preset I get a discreet result, but not great. My goal is to get the best possible recording of the lungs.  
(I am recording 2 CT scans of the same pig before ablation and after ablation, so in two distinct moments). I have questions

1. What is the difference between the various “3D CT, monomodal lung” I have more than one and I do not understand the difference? (I’m always referring to the preset)
2. Do you have any idea why it is not working? I get an error message. I’m using the same fixed and moving volume of “generic all”, but it doesn’t wok  
Thank you

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**Author:** ![Matteboo](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/matteboo/32/66548_2.png) [@Matteboo](https://discourse.slicer.org/u/Matteboo)\
**Post date:** [February 19, 2024, 12:19pm UTC](https://discourse.slicer.org/t/elastix-registration-3d-ct-monomodal-lung/34394/2 "2024-02-19T12:19:38Z")

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Hello,

One thing that could work is to segment the lung and to register only the lung if that’s the region of interest in your use case

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**Author:** ![Alice\_Durante](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/alice_durante/32/67737_2.png) [@Alice\_Durante](https://discourse.slicer.org/u/Alice_Durante)\
**Post date:** [February 19, 2024, 2:21pm UTC](https://discourse.slicer.org/t/elastix-registration-3d-ct-monomodal-lung/34394/3 "2024-02-19T14:21:10Z")

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How do I do this? I created two segments, one for pre ablation lungs and one for post ablation lungs. I applied a rigid linear transformation, trying to make both images and volumes coincide as much as possible, but when I use the “elastix” toolbox and try to insert the mask, it is as if my segmentations did not exist.  
Thank you

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**Author:** ![Alice\_Durante](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/alice_durante/32/67737_2.png) [@Alice\_Durante](https://discourse.slicer.org/u/Alice_Durante)\
**Post date:** [February 19, 2024, 2:30pm UTC](https://discourse.slicer.org/t/elastix-registration-3d-ct-monomodal-lung/34394/4 "2024-02-19T14:30:55Z")

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![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/5/5/550b028998b1ba062d2dc0d7559c164dcd7384c2.png) This is the error that i find

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**Author:** ![Matteboo](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/matteboo/32/66548_2.png) [@Matteboo](https://discourse.slicer.org/u/Matteboo)\
**Post date:** [February 19, 2024, 4:23pm UTC](https://discourse.slicer.org/t/elastix-registration-3d-ct-monomodal-lung/34394/5 "2024-02-19T16:23:50Z")

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Did you transform your segments into volume ?  
I don’t know a way to do it directly, I usually first convert it to a labelmap then transform the labelmap to volume using the “mask scalar volume toolbox”.  
Elastix only accept volume as input not segmentation, it might be why you couldn’t find them