# Finding displacement between an organ segment in two different CT Scans

**URL:** <https://discourse.slicer.org/t/finding-displacement-between-an-organ-segment-in-two-different-ct-scans/37052>\
**Category:** Support\
**Tags:** segmentation, segmentations, segment-editor\
**Created:** [June 26, 2024, 8:36pm UTC](https://discourse.slicer.org/t/finding-displacement-between-an-organ-segment-in-two-different-ct-scans/37052 "2024-06-26T20:36:36Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![zehret](https://avatars.discourse-cdn.com/v4/letter/z/bb73d2/32.png) [@zehret](https://discourse.slicer.org/u/zehret)\
**Post date:** [June 26, 2024, 8:36pm UTC](https://discourse.slicer.org/t/finding-displacement-between-an-organ-segment-in-two-different-ct-scans/37052/1 "2024-06-26T20:36:36Z")

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Hi,

I am trying to quantify the intra-fractional motion of the bladder, rectum and PTVs. I would like to be able to find the center of mass of organ segment, or a repeatable location within a segment, and calculate the displacement between this point at two different times. I have the CT slices and the structure sets of the organs at two different times but I cannot find the CoM or the displacement. Any advice/knowledge is apprecaited. Thank you!