# Threshold is not working in attached DICOM data

**URL:** <https://discourse.slicer.org/t/threshold-is-not-working-in-attached-dicom-data/29619>\
**Category:** Support\
**Tags:** segmentation, dicom\
**Created:** [May 24, 2023, 4:59am UTC](https://discourse.slicer.org/t/threshold-is-not-working-in-attached-dicom-data/29619 "2023-05-24T04:59:24Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Dwij\_Mistry](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/dwij_mistry/32/15265_2.png) [@Dwij\_Mistry](https://discourse.slicer.org/u/Dwij_Mistry)\
**Post date:** [May 24, 2023, 4:59am UTC](https://discourse.slicer.org/t/threshold-is-not-working-in-attached-dicom-data/29619/1 "2023-05-24T04:59:24Z")

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I was working with a patient’s data, and it loaded perfectly. However, when I attempted to perform a threshold operation, I noticed that it only applied to the top right corner.

you can download the DICOM data from : [https://www.dropbox.com/s/ts69c4mirm89153/TD3\_Maxilla%20mandible%20%26%20cervical%20vtb%20%281%29.zip?dl=0](https://www.dropbox.com/s/ts69c4mirm89153/TD3_Maxilla%20mandible%20%26%20cervical%20vtb%20%281%29.zip?dl=0)

Here is the evidence in the slicer:

[https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/6/a/6a15b58c698aa461a04afcf0a34c43e3e32dee25.mp4](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/6/a/6a15b58c698aa461a04afcf0a34c43e3e32dee25.mp4)

Step1 selecting threshold range

 ![step 1](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/9/6/967293b0adb2e05666858285cdf6a8990912b301.png)

Step2 after applying the threshold

 ![step 2](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/1/d/1d1bdd1ef980e220b9f67ba43f64c95e73f33bd0.jpeg)

And here is the evidence in Mimics:

[https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/f/1/f1f0319c2ae8bab71a5f26919e939d8c95990db1.mp4](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/f/1/f1f0319c2ae8bab71a5f26919e939d8c95990db1.mp4)

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<div class="post-metadata">

**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:** [May 24, 2023, 5:36pm UTC](https://discourse.slicer.org/t/threshold-is-not-working-in-attached-dicom-data/29619/2 "2023-05-24T17:36:54Z")

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Probably you need to set the set the segmentation geometry to match the volume. Pick the button with the box (above the white arrow in red circle) to get the dialog shown below. Then pick the CT as the source geometry.

![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/e/b/eb7df4c6112f1b797810fffde93c7ee39818a546.png)