# Query with ROI selection

**URL:** <https://discourse.slicer.org/t/query-with-roi-selection/9188>\
**Category:** Support\
**Tags:** segmentation\
**Created:** [November 18, 2019, 1:00pm UTC](https://discourse.slicer.org/t/query-with-roi-selection/9188 "2019-11-18T13:00:06Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![RadioQuest](https://avatars.discourse-cdn.com/v4/letter/r/85f322/32.png) [@RadioQuest](https://discourse.slicer.org/u/RadioQuest)\
**Post date:** [November 18, 2019, 1:00pm UTC](https://discourse.slicer.org/t/query-with-roi-selection/9188/1 "2019-11-18T13:00:06Z")

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Hi…

How can we select the ROI of the same dimension?

When selecting Paint size as 3% , area is selected but these dimensions seem to change for another area/ slice when the image is zoomed.

Is there any way to get fixed-sized ROI for analysis? For example : 2cm diameter circle?

Thank You

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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:** [November 18, 2019, 9:28pm UTC](https://discourse.slicer.org/t/query-with-roi-selection/9188/2 "2019-11-18T21:28:06Z")

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In Segment Editor module, you can specify the brush size in percentage of screen size or as absolute size (in mm). Click the `%` or `mm` button on the right side of the `Diameter` row to toggle between them.

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<div class="post-metadata">

**Author:** ![RadioQuest](https://avatars.discourse-cdn.com/v4/letter/r/85f322/32.png) [@RadioQuest](https://discourse.slicer.org/u/RadioQuest)\
**Post date:** [January 27, 2020, 3:08pm UTC](https://discourse.slicer.org/t/query-with-roi-selection/9188/3 "2020-01-27T15:08:48Z")

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Thank you very much. This is helpful. I appreciate your support