# Registration method for automatically segmented 2D US slices

**URL:** <https://discourse.slicer.org/t/registration-method-for-automatically-segmented-2d-us-slices/22717>\
**Category:** Support\
**Tags:** registration, segmentation, automation\
**Created:** [March 28, 2022, 10:42am UTC](https://discourse.slicer.org/t/registration-method-for-automatically-segmented-2d-us-slices/22717 "2022-03-28T10:42:29Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Marijn\_H](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/marijn_h/32/9366_2.png) [@Marijn\_H](https://discourse.slicer.org/u/Marijn_H)\
**Post date:** [March 28, 2022, 10:42am UTC](https://discourse.slicer.org/t/registration-method-for-automatically-segmented-2d-us-slices/22717/1 "2022-03-28T10:42:29Z")

</div>

I am trying to automatically register tracked US images to a CT scan (with 3D model). I already developed a way to automatically segment bone from US images in real-time. The segmented binary image can be loaded in slicer as scalar volume or labelmap, which looks like this:

![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/b/3/b3eda0d1088fabfb7c0a7d3620b269abbdec8a24.png)

Now, I am trying to find a way to register these segmentations to the CT scan, but I am a bit struggling which method is most efficient. I tried exporting each 2D segmentation to a 3D volume, but then you end up with a lot of different segments in the slicer scene. I also tried the volume reconstruction module, but this results in a 3D segmentation with a thickness of multiple millimeters, while I only want the bone surface. I was also thinking: maybe it is possible to convert each 2D US segmentation to a 3D point cloud? Then the point cloud can be registered to the CT bone model with the fiducials-model registration module.

Which method do you think is most efficient? Or do you have other suggestions?