# Regard to drawing ROI & background.

**URL:** <https://discourse.slicer.org/t/regard-to-drawing-roi-background/30479>\
**Category:** Support\
**Tags:** segmentation\
**Created:** [July 9, 2023, 7:44pm UTC](https://discourse.slicer.org/t/regard-to-drawing-roi-background/30479 "2023-07-09T19:44:55Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Waleed](https://avatars.discourse-cdn.com/v4/letter/w/a87d85/32.png) [@Waleed](https://discourse.slicer.org/u/Waleed)\
**Post date:** [July 9, 2023, 7:44pm UTC](https://discourse.slicer.org/t/regard-to-drawing-roi-background/30479/1 "2023-07-09T19:44:55Z")

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Operating system:  
Slicer version: 5.2.2  
Expected behavior:  
Actual behavior:

I have question regarding drawing 11 ROIs around the Catphan phantom, but im wondering:

1. Is it necessary to draw a background around ROI? If so, could you please guide me on how to do it effectively?
2. Is it required to draw the ROIs to cover the entire area 100%, or can there be some areas that are partially missing? I would like to know if this would have any impact on the resulting analysis.

Thank you in advance for your valuable support and guidance.

Waleed