# Register two 2D images (EPID and DRR)

**URL:** <https://discourse.slicer.org/t/register-two-2d-images-epid-and-drr/45057>\
**Category:** Support\
**Tags:** registration\
**Created:** [November 12, 2025, 10:07pm UTC](https://discourse.slicer.org/t/register-two-2d-images-epid-and-drr/45057 "2025-11-12T22:07:58Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![ruju](https://avatars.discourse-cdn.com/v4/letter/r/ea666f/32.png) [@ruju](https://discourse.slicer.org/u/ruju)\
**Post date:** [November 12, 2025, 10:07pm UTC](https://discourse.slicer.org/t/register-two-2d-images-epid-and-drr/45057/1 "2025-11-12T22:07:58Z")

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Hi,

I would like to register two 2D images in 3D Slicer, one is an EPID image and the other is a computed DRR. Unfortunately, the EPID image does not contain any geometric information, so it is placed arbitrarily when loaded into 3D Slicer.

I tried using the Transform module, but applying the coordinates of the DRR’s position as transformation parameters does not align the EPID with the DRR plane. I also attempted registration with the General Registration (BRAINS) module, but it did not work because the images are 2D and lack a third dimension. Do you have any suggestions on how to correctly align or register 2D images in 3D Slicer?

Thanks in advance for your help!