List of supported DICOM attributes

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1

Hello! I’ve been researching Orthanc database data and came across a table called MainDicomTags where i can find many dicom tags and interesting info. But i have a few doubts about it:

Are the following attributes related to the series and not to the study?
Body part examined;
Modality;
Manufacturer.

The other question is: is there a list of supported DICOM attributes that Orthanc stores from exams?

Thanks!

2

Hi,

Orthanc uses dmtkc for the dicom tags dictionary.
The dctmk data dictionary is built based on the part 6 of the DICOM standard (https://support.dcmtk.org/docs/file_datadict.html).
You can find the list of these tags here: http://dicom.nema.org/dicom/2003/03_06PU.PDF

Cheers,

Michel

3

Hello,

The so-called “MainDicomTags” are a subset of the most useful DICOM tags. It is purely specific to Orthanc, and is not at all related to the DICOM standard.

This subset of tags is written directly into the database index, which enables quicker access to the tags it contains, typically while doing lookups (no need to parse a DICOM file on the disk).

The definition of the subsets for the patient/study/series/instance levels can be found at the top of the “Core/DicomFormat/DicomMap.cpp” source file from Orthanc:
https://bitbucket.org/sjodogne/orthanc/src/Orthanc-1.5.8/Core/DicomFormat/DicomMap.cpp#lines-49

Check out the content of “studyTags” to get the list of study-related main DICOM tags.

“Body part examined”, “Modality” and “Manufacturer” are main DICOM tags related to the series level (not study-related), as one study can be made from multiple series, possibly coming from various manufacturers.

HTH,
Sébastien-

4

I too found this a bit strange. Most PACS vendors I have worked with at least roll up the Modality and Body part to the study level even if you can technically have multiple of them at a lower level. For example GE PACS UV100 gets the modality from the first image and assigns it at the study level. This isn’t always ideal since you could end up with SC, PR, OT, etc but it will usually get it correct. I have worked with one that had a Modality code at the study level that might look like CT/SC or CT/SC/OT.

In addition, body part is usually used in a PACS as a method to find relevant priors. Relevant priors are obviously pulled at the study level, not the series level.This part might have more to do with an order/procedure than the dicom.

5

Hello,

Thanks for your feedback. In either case, it is possible to create a plugin that would copy some of the “MainDicomTags” from the series level into the study level, by overwriting parts of the REST API. Check out function “OrthancPluginRegisterRestCallback()” in the Orthanc plugin SDK:
https://book.orthanc-server.com/developers/creating-plugins.html

You could also easily develop a higher-level interface on the top of the Orthanc REST API:
https://book.orthanc-server.com/faq/improving-interface.html

HTH,
Sébastien-

6

I see! So there are DICOM tags related to series and instances. I thought that DICOM tags were only related to studies.

I am researching Orthanc’s database in order to collect some metrics and understand a DICOM exam structure. Orthanc makes it really easy to work with DICOM files and read its data.

Thank you all for the answers!