# What is the minimum unit of pixel value in CT

**URL:** <https://discourse.slicer.org/t/what-is-the-minimum-unit-of-pixel-value-in-ct/38134>\
**Category:** Support\
**Created:** [August 30, 2024, 6:30pm UTC](https://discourse.slicer.org/t/what-is-the-minimum-unit-of-pixel-value-in-ct/38134 "2024-08-30T18:30:35Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![soil\_soil](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/soil_soil/32/77780_2.png) [@soil\_soil](https://discourse.slicer.org/u/soil_soil)\
**Post date:** [August 30, 2024, 6:30pm UTC](https://discourse.slicer.org/t/what-is-the-minimum-unit-of-pixel-value-in-ct/38134/1 "2024-08-30T18:30:35Z")

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The smallest unit of the fountain pen in segmentation is the smallest pixel of CT, but the distribution of brightness and darkness can be seen within a single pixel. How is the intensity value within a single pixel determined

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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:** [August 30, 2024, 6:32pm UTC](https://discourse.slicer.org/t/what-is-the-minimum-unit-of-pixel-value-in-ct/38134/2 "2024-08-30T18:32:34Z")

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When the CT image is displayed, the continuous signal is reconstructed from the discrete samples. That’s why you always see a continuous gray level changes, regardless of how much you zoom in.

You can find voxel spacing of the image in Volumes module / Volume information section. You can find voxel spacing of the segmentation if you click the “Segment Geometry” button in Segment Editor.