# Documented threshold values for various body parts

**URL:** <https://discourse.slicer.org/t/documented-threshold-values-for-various-body-parts/4510>\
**Category:** Support\
**Tags:** segmentation\
**Created:** [October 23, 2018, 6:22pm UTC](https://discourse.slicer.org/t/documented-threshold-values-for-various-body-parts/4510 "2018-10-23T18:22:20Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![EricWilson](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ericwilson/32/1513_2.png) [@EricWilson](https://discourse.slicer.org/u/EricWilson)\
**Post date:** [October 23, 2018, 6:22pm UTC](https://discourse.slicer.org/t/documented-threshold-values-for-various-body-parts/4510/1 "2018-10-23T18:22:20Z")

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Hello,

Is there some kind of documentation about exactly what threshold values to use on various body parts to get the best segments?

if there is, how accurate is it, can it easily and cleanly separate things like skin, liver, heart and various organ tissues?

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**Author:** ![pieper](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/pieper/32/8_2.png) [@pieper](https://discourse.slicer.org/u/pieper)\
**Post date:** [October 23, 2018, 6:46pm UTC](https://discourse.slicer.org/t/documented-threshold-values-for-various-body-parts/4510/2 "2018-10-23T18:46:28Z")

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No sorry, it’s not exactly paint-by-numbers 🙂

If you are working with CT, [this scale might help.](https://en.wikipedia.org/wiki/Hounsfield_scale) If you are working with MR then mostly the images are not in physical units and only relative intensity values are meaningful.

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**Author:** ![EricWilson](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ericwilson/32/1513_2.png) [@EricWilson](https://discourse.slicer.org/u/EricWilson)\
**Post date:** [October 23, 2018, 7:32pm UTC](https://discourse.slicer.org/t/documented-threshold-values-for-various-body-parts/4510/3 "2018-10-23T19:32:40Z")

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I was afraid it would be an inexact science.

in that case, how would you do something like creating an accurate segment from a CT scan of a heart that has a hole in the side?

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**Author:** ![pieper](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/pieper/32/8_2.png) [@pieper](https://discourse.slicer.org/u/pieper)\
**Post date:** [October 23, 2018, 7:46pm UTC](https://discourse.slicer.org/t/documented-threshold-values-for-various-body-parts/4510/4 "2018-10-23T19:46:25Z")

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You could start with the tutorials - the second one on this list shows how to do a nice heart segmentation pretty quickly:

[https://www.slicer.org/wiki/Documentation/4.10/Training#Slicer4\_Image\_Segmentation](https://www.slicer.org/wiki/Documentation/4.10/Training#Slicer4_Image_Segmentation)