# From CT to qCT?

**URL:** <https://discourse.slicer.org/t/from-ct-to-qct/11782>\
**Category:** Support\
**Created:** [May 29, 2020, 6:52pm UTC](https://discourse.slicer.org/t/from-ct-to-qct/11782 "2020-05-29T18:52:01Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![gsolit](https://avatars.discourse-cdn.com/v4/letter/g/d07c76/32.png) [@gsolit](https://discourse.slicer.org/u/gsolit)\
**Post date:** [May 29, 2020, 6:52pm UTC](https://discourse.slicer.org/t/from-ct-to-qct/11782/1 "2020-05-29T18:52:01Z")

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Dear all  
Is there an extension that allows to extract segment statistics for known CT calibration parameters?  
I would like to extract bone density values instead of HU.  
Thanks

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**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:** [May 29, 2020, 11:56pm UTC](https://discourse.slicer.org/t/from-ct-to-qct/11782/2 "2020-05-29T23:56:36Z")

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Segment statistics reports results in whatever unit your image contains. If you have a calibration formula then you can easily transform your voxel values according to that, before you compute statistics.

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**Author:** ![gsolit](https://avatars.discourse-cdn.com/v4/letter/g/d07c76/32.png) [@gsolit](https://discourse.slicer.org/u/gsolit)\
**Post date:** [May 30, 2020, 8:31pm UTC](https://discourse.slicer.org/t/from-ct-to-qct/11782/3 "2020-05-30T20:31:20Z")

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Dr Lasso  
Can I ask how the voxel values can be transformed in slicer?  
Since I would like to use different formulae, is it possible to apply the different transformations for different voxel values intervals?  
Thank you so much for your quick reply.

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**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:** [May 31, 2020, 12:48am UTC](https://discourse.slicer.org/t/from-ct-to-qct/11782/4 "2020-05-31T00:48:34Z")

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Yes, you can transform the values any way you want by getting voxel array as a numpy array and then use standard Python functions on that array. See [examples in the script repository](https://www.slicer.org/wiki/Documentation/Nightly/ScriptRepository#Add_noise_to_image).

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**Author:** ![gsolit](https://avatars.discourse-cdn.com/v4/letter/g/d07c76/32.png) [@gsolit](https://discourse.slicer.org/u/gsolit)\
**Post date:** [May 31, 2020, 6:51pm UTC](https://discourse.slicer.org/t/from-ct-to-qct/11782/5 "2020-05-31T18:51:14Z")

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Thanks a lot Dr Lasso