# Unit correct for my DICOM Data

**URL:** https://discourse.slicer.org/t/unit-correct-for-my-dicom-data/13153
**Category:** Support
**Created:** [August 25, 2020, 9:48am UTC](https://discourse.slicer.org/t/unit-correct-for-my-dicom-data/13153 "2020-08-25T09:48:55Z")
**Posts on this page:** 5
**Page:** 1

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### Author: ![Jini](https://avatars.discourse-cdn.com/v4/letter/j/5daacb/32.png) [@Jini](https://discourse.slicer.org/u/Jini)
#### Post date: [August 25, 2020, 9:48am UTC](https://discourse.slicer.org/t/unit-correct-for-my-dicom-data/13153/1 "2020-08-25T09:48:55Z")

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Where can you calibrate or set the unit of the 3D slicer. By the segmentation and volume it shows me in mm, is this unit correct?

Thanks

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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: [August 25, 2020, 12:13pm UTC](https://discourse.slicer.org/t/unit-correct-for-my-dicom-data/13153/2 "2020-08-25T12:13:58Z")

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Yes, if the dicom data follows the standard then Slicer will show the units correctly in millimeters. If the units are not correct for some reason you can change them in the Volumes module.

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### Author: ![Jini](https://avatars.discourse-cdn.com/v4/letter/j/5daacb/32.png) [@Jini](https://discourse.slicer.org/u/Jini)
#### Post date: [August 25, 2020, 4:29pm UTC](https://discourse.slicer.org/t/unit-correct-for-my-dicom-data/13153/3 "2020-08-25T16:29:17Z")

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How do I know if the unit is properly adjusted? does I have to calculate something from dicom data?

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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: [August 25, 2020, 4:32pm UTC](https://discourse.slicer.org/t/unit-correct-for-my-dicom-data/13153/4 "2020-08-25T16:32:51Z")

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If you know the actual size of something in the images you can use a ruler or line markup in slicer to measure it and compare. Do you have some reason to think your dicom data is invalid?

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### Author: ![Jini](https://avatars.discourse-cdn.com/v4/letter/j/5daacb/32.png) [@Jini](https://discourse.slicer.org/u/Jini)
#### Post date: [August 26, 2020, 11:47am UTC](https://discourse.slicer.org/t/unit-correct-for-my-dicom-data/13153/5 "2020-08-26T11:47:06Z")

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the middle ear is very small and I can’t imagine that the deflection is in mm. I don’t know how to set it automatically without measuring it manually with a ruler. Do I have to take data from the DICOM for the setting?  
I have to be able to calculate it somehow back to check whether the unit can be correct?

Thanks