Have you ever run into this situation: the patient is lying on the CT sim table head first prone (HFP), but the technician accidentally selected the wrong scan orientation of head first supine (HFS). Then, a lot of problems will happen down the road. The image is displayed incorrectly Left and Right; The treatment plan designed on the image set will be wrong; The treatment delivery and IGRT will be off…..
Do we need to call the patient and have him/her come back for a re-simulation to correct the “error”? The good news is: NOT NEEDED! In this post, I will show you how to edit the DICOM tag(s) so that we don’t need to call the patient back to SAVE TIME and RESOURCES!
In this example, I will show you how to do this using MIM software, but you can use any DICOM editing tools.
1.Right click on the CT image dataset, choose “show DICOM info”
2.Then edit following DICOM tags, apply the change to all images in the series:
–(0018, 5100) Patient Position (HFP, HFS, etc, this is just a string)-you can also do this step via “change pt orientation” option, but doing this alone is not ENOUGH!
–(0020,0037) Image Orientation Patient, this is the public tag that other systems “see”, such as TPS, machine CBCT etc., for HFS, it is [1,0,0,0,1,0], for HFP it is [-1,0,0,0,-1,0]; This step is the KEY to make it WORK!
If you change orientation via “change pt orientation” option, the MIM private tag will be created [3773,300D], but that alone will only make images “appear correct” in MIM only, other systems such as TPS won’t recognize this!
So, in summary, the key DICOM tag to change is (0020,0037)
If you have any questions or need further clarification, feel free to leave a comment below!
See you next time!