# Does the " intensity range" mean the "Hounsfield unit" on CT dicom image?

**URL:** <https://discourse.slicer.org/t/does-the-intensity-range-mean-the-hounsfield-unit-on-ct-dicom-image/6765>\
**Category:** Support\
**Created:** [May 12, 2019, 8:25am UTC](https://discourse.slicer.org/t/does-the-intensity-range-mean-the-hounsfield-unit-on-ct-dicom-image/6765 "2019-05-12T08:25:41Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![markyang19](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@markyang19](https://discourse.slicer.org/u/markyang19)\
**Post date:** [May 12, 2019, 8:25am UTC](https://discourse.slicer.org/t/does-the-intensity-range-mean-the-hounsfield-unit-on-ct-dicom-image/6765/1 "2019-05-12T08:25:41Z")

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I am trying the segmentation editor by intensity range on my CT dicom image.  
Does the " intensity range" mean the “Hounsfield unit” on CT dicom image???  
I compare the same dicom image on the 3D slicer and other dicom viewer. It seems the " intensity range" on 3D slicer equal to Hounsfield unit. But I am not sure about this point.

Operating system: Windows 10  
Slicer version: 4.11.0  
Expected behavior: segmentation by intensity range  
Actual behavior:

 ![intensity%20range](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/8/a/8a79be0494bfd728b348f4ffa2f50dbad0e9817b.jpeg)

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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 12, 2019, 12:16pm UTC](https://discourse.slicer.org/t/does-the-intensity-range-mean-the-hounsfield-unit-on-ct-dicom-image/6765/2 "2019-05-12T12:16:12Z")

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> [@markyang19](#):
>
> Does the " intensity range" mean the “Hounsfield unit” on CT dicom image???

Yes, voxel values of a CT volume is in HU.

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**Author:** ![markyang19](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@markyang19](https://discourse.slicer.org/u/markyang19)\
**Post date:** [May 12, 2019, 2:33pm UTC](https://discourse.slicer.org/t/does-the-intensity-range-mean-the-hounsfield-unit-on-ct-dicom-image/6765/3 "2019-05-12T14:33:14Z")

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Dear Andras Lasso:  
Thank you for your kindly replay.

Regards,  
Mark

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**Author:** ![kookoo9999](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/kookoo9999/32/12394_2.png) [@kookoo9999](https://discourse.slicer.org/u/kookoo9999)\
**Post date:** [November 8, 2021, 2:37pm UTC](https://discourse.slicer.org/t/does-the-intensity-range-mean-the-hounsfield-unit-on-ct-dicom-image/6765/4 "2021-11-08T14:37:15Z")

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@lassoan  
Hi ,while searching for the House Field unit, I have a question here.

> [@lassoan](#):
>
> Yes, voxel values of a CT volume is in HU.

According to this comment, is it correct to indicate the segmented HA value in the segment editor in the picture?

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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:** [November 8, 2021, 2:58pm UTC](https://discourse.slicer.org/t/does-the-intensity-range-mean-the-hounsfield-unit-on-ct-dicom-image/6765/5 "2021-11-08T14:58:55Z")

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Yes, in clinical CT images, voxel values are in HU and the threshold range is defined in HU.