# Is it possible to edit the ImageOrientationPatient DICOM tag in slicer?

**URL:** <https://discourse.slicer.org/t/is-it-possible-to-edit-the-imageorientationpatient-dicom-tag-in-slicer/2648>\
**Category:** Support\
**Tags:** registration\
**Created:** [April 20, 2018, 1:42pm UTC](https://discourse.slicer.org/t/is-it-possible-to-edit-the-imageorientationpatient-dicom-tag-in-slicer/2648 "2018-04-20T13:42:36Z")\
**Posts on this page:** 7\
**Page:** 1

<div class="post-metadata">

**Author:** ![Lowey](https://avatars.discourse-cdn.com/v4/letter/l/e36b37/32.png) [@Lowey](https://discourse.slicer.org/u/Lowey)\
**Post date:** [April 20, 2018, 1:42pm UTC](https://discourse.slicer.org/t/is-it-possible-to-edit-the-imageorientationpatient-dicom-tag-in-slicer/2648/1 "2018-04-20T13:42:36Z")

</div>

Hi,

I am hoping it is possible to edit the ImageOrientationPatient DICOM tag and associated image within Slicer.

My problem,

I have a CT image which has been transformed with 6 degrees of freedom (3 Translations and 3 Rotations), hence, its ImageOrientationPatient DICOM tag has gone from [1;0;0;0;1;0] to [0.9998;0.0189;0.0056;-0.0189;0.9998;-0.0056]

I want to dose a dose calculation on the transformed CT, however, my treatment planning system does not allow dose calculations on tilted images. Is there a way I can correct the ImageOrientationPatient DICOM tag back to [1;0;0;0;1;0] within Slicer? This would also be required for the radiotherapy structures DICOM file too

Many thanks!!

---

<div class="post-metadata">

**Author:** ![ihnorton](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ihnorton/32/9_2.png) [@ihnorton](https://discourse.slicer.org/u/ihnorton)\
**Post date:** [April 20, 2018, 1:54pm UTC](https://discourse.slicer.org/t/is-it-possible-to-edit-the-imageorientationpatient-dicom-tag-in-slicer/2648/2 "2018-04-20T13:54:36Z")

</div>

~~I don’t think this can be done within Slicer, but there are command line tools that can edit headers.~~

As you are likely aware, extreme caution, prudence, and oversight should be exercised when integrating any non-standard modifications into a human clinical pipeline. Note that Slicer is not FDA approved (although some Slicer-based products could potentially be – with liability assumed by the providing commercial entity). The open source Slicer license [explicitly disclaims liability](https://github.com/Slicer/Slicer/blob/0f8926d1391f5abc2be845890dae369453465317/License.txt#L147-L156) for clinical use.

---

<div class="post-metadata">

**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:** [April 20, 2018, 9:06pm UTC](https://discourse.slicer.org/t/is-it-possible-to-edit-the-imageorientationpatient-dicom-tag-in-slicer/2648/3 "2018-04-20T21:06:36Z")

</div>

Actually, Slicer can solve this. Correct loading of tilted-gantry images has been recently added. You have to enable application of an acquisition transform in Application Settings / DICOM section. Then:

- load the volume from DICOM
- go to Transforms module and “harden” on the acquisition transform on the volume
- go to Data module and right-click on the volume to export to DICOM

Gantry-tilted acquisitions are quite rare and so this feature is not tested extensively, but it should work. Let us know if you have any issues.

---

<div class="post-metadata">

**Author:** ![Lowey](https://avatars.discourse-cdn.com/v4/letter/l/e36b37/32.png) [@Lowey](https://discourse.slicer.org/u/Lowey)\
**Post date:** [April 23, 2018, 1:45am UTC](https://discourse.slicer.org/t/is-it-possible-to-edit-the-imageorientationpatient-dicom-tag-in-slicer/2648/4 "2018-04-23T01:45:02Z")

</div>

Thank you kindly for your reply! Much appreciated!

---

<div class="post-metadata">

**Author:** ![Lowey](https://avatars.discourse-cdn.com/v4/letter/l/e36b37/32.png) [@Lowey](https://discourse.slicer.org/u/Lowey)\
**Post date:** [May 2, 2018, 4:33am UTC](https://discourse.slicer.org/t/is-it-possible-to-edit-the-imageorientationpatient-dicom-tag-in-slicer/2648/5 "2018-05-02T04:33:37Z")

</div>

Hi Andras,

I have tried the approach you suggested above but seem to be having difficulty. I am using Slice version 4.8.1

To confirm, this is what I have done,

1. Open Slicer, go to Edit \> Application Settings. Then under the DICOM section I changed the Acquisition geometry regularization field to ‘apply regularization transform’
2. Imported my tilted CT volume. Note the gantry isn’t tilted but the treatment couch is, leading to a non-[1;0;0;0;1;0] value for ImageOrientationPatient
3. Went to the Transforms module, but there is no ‘acquisition transform’ to harden
4. I tried hardening a new transform, but after exporting the DICOM CT volume is still tilted

Any suggestions would be fantastic!

EDIT: I have found that for some patient data, I am indeed able to harden the ‘deformed image export acquisition transform’. However, once I export this, my treatment planning system still registers a tilted image

Thanks

---

<div class="post-metadata">

**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:** [May 2, 2018, 5:57am UTC](https://discourse.slicer.org/t/is-it-possible-to-edit-the-imageorientationpatient-dicom-tag-in-slicer/2648/6 "2018-05-02T05:57:18Z")

</div>

If gantry was not tilted then it is even simpler: save your data set as .nrrd file, then load the .nrrd file - but before clicking OK in “Add data…” dialog check “Show options” checkbox and check “Ignore Orientation” checkbox.

---

<div class="post-metadata">

**Author:** ![JFC](https://avatars.discourse-cdn.com/v4/letter/j/8baadc/32.png) [@JFC](https://discourse.slicer.org/u/JFC)\
**Post date:** [June 25, 2025, 8:01am UTC](https://discourse.slicer.org/t/is-it-possible-to-edit-the-imageorientationpatient-dicom-tag-in-slicer/2648/7 "2025-06-25T08:01:21Z")

</div>

Dear Nick:  
I am new with 3D slicer. Please, may I conatct you regarding the same issue you posted?. Thanks so much for your support. Sincerely  
Juan Francisco