# Gamma index in 3D slicer

**URL:** <https://discourse.slicer.org/t/gamma-index-in-3d-slicer/35639>\
**Category:** Support\
**Created:** [April 21, 2024, 7:39am UTC](https://discourse.slicer.org/t/gamma-index-in-3d-slicer/35639 "2024-04-21T07:39:43Z")\
**Posts on this page:** 1\
**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:** [April 21, 2024, 7:39am UTC](https://discourse.slicer.org/t/gamma-index-in-3d-slicer/35639/1 "2024-04-21T07:39:44Z")

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3D slicer version: 5.2.2  
Hi every one  
I have 2 RT Dose. In the 3D Slicer software, using the gamma comparison module, these dose distributions obtained from the TPS have been compared. In this process, the CT images imported into the TPS have a slice thickness of 5 mm , and the analysis indices were 3%-3mm.  
considering that in these conditions, the 3mm index is less than the spatial resolution of the CT (which is 5mm), how does the 3D Slicer software perform this task?

Thanks a lot