How to read the value of certain attribute (tag) in DICOM Metadata" from "Python Interactor"

Hi Dears 3DSlicer developers

After loading dicom files using DICOM module, how can I access the value of certain attribute (tag) in “DICOM Metadata” from Python Interactor?

For example, I want to access the value of IsocenterPosition with the tag number (300a,012c) from Python Interactor. How can I do that?

Please guide me,
Thanks a lot.

Hi -

Here are some examples - let us know if this doesn’t cover your use case.


Hi Steve

Thanks a lot for sending to me the link to ScriptRepository.

I can access to tags such as (0020,0010) to (300a,000c), but unfortunately I can not read tags that are located in item, such as (300a,012c), highlighted in the following figure.

The following figure is screenshot of DICOM File Browser and the tag that I want to access its value (300a,012c).

I enter the following commands:
>>> patientList=db.patients()
>>> studyList=db.studiesForPatient(patientList[0])
>>> seriesList=db.seriesForStudy(studyList[0])
>>> fileList=db.filesForSeries(seriesList[0])
>>> print(db.fileValue(fileList[0],‘300a,000c’))
>>> print(db.fileValue(fileList[0],‘300a,012c’))


As you see, the last command dose not give any output.
Please guide me to access tags that are loacted in Items.
Thanks a lot.

Hi Shahrokh -

Ah, sorry - you are right, the database doesn’t cache nested tags, only top level ones.

I added a new section to the script repository showing how to access nested tags using pydicom.


Hi Dear Steve
Thank you very much for the link you provided. I study it now.
But I accidentally solved my problem according to the description given on the site of Pydicom User Guide — pydicom 1.0a documentation.

In JupyterLab, I enter the following commands:

[1]: import pydicom
[2]: ds = dicom.read_file("112325-00000000.dcm")
[3]: ds
(300a, 00b0)  Beam Sequence   2 item(s) ---- 
   (300a, 00b2) Treatment Machine Name              SH: 'Compact'
   (300a, 0111)  Control Point Sequence   2 item(s) ---- 
      (300a, 0112) Control Point Index                 IS: "0"
      (300a, 012c) Isocenter Position                  DS: ['111.908', '-52.0623', '-1212.2']
[4]: ds[0x300a,0xb0][0][0x300a,0x111][0][0x300a,0x12c].value
['111.908', '-52.0623', '-1212.2']

But this method is difficult. :thinking:

Best regards.

1 Like

Yes, getting data out of nested dicom sequences is kind of awkward. The example I linked is abit easier to read, since it uses the dicom dictionary name instead of the hex tag. ds.CTExposureSequence[0].ExposureModulationType