# Changing the Hounsfield unit in a DICOM CT image

**URL:** <https://discourse.slicer.org/t/changing-the-hounsfield-unit-in-a-dicom-ct-image/42370>\
**Category:** Support\
**Created:** [March 30, 2025, 8:05am UTC](https://discourse.slicer.org/t/changing-the-hounsfield-unit-in-a-dicom-ct-image/42370 "2025-03-30T08:05:27Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![azam](https://avatars.discourse-cdn.com/v4/letter/a/ea666f/32.png) [@azam](https://discourse.slicer.org/u/azam)\
**Post date:** [March 30, 2025, 8:05am UTC](https://discourse.slicer.org/t/changing-the-hounsfield-unit-in-a-dicom-ct-image/42370/1 "2025-03-30T08:05:27Z")

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Hi everyone  
I have a CT image in DICOM format that I exported it from Brachytherapy treatment planning system. I want to remove the Brachy applicators from the CT image. In other words, I want to change its Hounsfield unit to a desired value of zero. I have no idea about this. Can you guide me?  
Thanks a lot

 ![Screenshot_1](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/d/1/d12674bd377bd84456442d89fef4a86d54973d95.png)

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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:** [March 30, 2025, 2:08pm UTC](https://discourse.slicer.org/t/changing-the-hounsfield-unit-in-a-dicom-ct-image/42370/2 "2025-03-30T14:08:53Z")

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You can use the Masking effect in the Segment Editor for that.

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**Author:** ![Eka\_Mulyani](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/eka_mulyani/32/80136_2.png) [@Eka\_Mulyani](https://discourse.slicer.org/u/Eka_Mulyani)\
**Post date:** [May 15, 2025, 3:52am UTC](https://discourse.slicer.org/t/changing-the-hounsfield-unit-in-a-dicom-ct-image/42370/3 "2025-05-15T03:52:15Z")

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Hi, I am a beginner using 3DSlicer. I worked on the nrrd file to dicom, after I checked in TPS, the HU value is still 0 and 1. How do I set the HU so that the value obtained is around 200