# HU to ED automatic conversion

**URL:** <https://opentps.discourse.group/t/hu-to-ed-automatic-conversion/58>\
**Category:** General\
**Created:** [April 29, 2025, 7:53am UTC](https://opentps.discourse.group/t/hu-to-ed-automatic-conversion/58 "2025-04-29T07:53:23Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![wright\_guy](https://avatars.discourse-cdn.com/v4/letter/w/da6949/32.png) [@wright\_guy](https://opentps.discourse.group/u/wright_guy)\
**Post date:** [April 29, 2025, 7:53am UTC](https://opentps.discourse.group/t/hu-to-ed-automatic-conversion/58/1 "2025-04-29T07:53:23Z")

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Hi,  
I am just getting familiar with openTPS and have found that when I press “calculate beamlets” in the optimisation tab for an IMRT plan, my whole volume (which was in HU) gets converted to electron density and therefore everything just looks homogeneous grey. And once I compute dose in the Dose Computation tab it seems to apply the same rescaling and everything just becomes 1.  
Any ideas why this is happening and how to stop it?  
Thanks in advance 🙂

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**Author:** ![Eliot-P](https://yyz2.discourse-cdn.com/free1/user_avatar/opentps.discourse.group/eliot-p/32/6_2.png) [@Eliot-P](https://opentps.discourse.group/u/Eliot-P)\
**Post date:** [May 1, 2025, 2:50pm UTC](https://opentps.discourse.group/t/hu-to-ed-automatic-conversion/58/2 "2025-05-01T14:50:53Z")

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Dear OpenTPS user,

Could you please provide some screenshots of the issue you are experiencing, along with your planning parameters? This will help us assist you as effectively as possible.

Regards,  
Eliot