Extract text for whether Philips CT AEC used

[David Platten]

A new Philips Ingenuity CT scanner stores "3D MODULATION" in image tag 0018,9323 if full mA modulation used. However, this isn't displayed in the "X-ray modulation type" in ctdetailed.html.

It may be that this information is present in the image DICOM tags, but not in the structured dose report.

(This works fine for the Siemens Definition AS system (stores "Z_EC" in the 0018,9323 tag)).

[David Platten]

I've looked through a structured dose report from the scanner: there is no mention of mA modulation.

However, I have also looked through a Siemens dose report where Z_EC was used, and can't find the text "Z_EC" in the dose report: where does the "Z_EC" come from? I'll have a look at the rdsr.py extractor to see if I can find out.

[David Platten]

OK. Lines 513 to 522 in rdsr.py seem to look for x-ray modulation type:

        if cont.ConceptNameCodeSequence[0].CodeMeaning.lower() == 'x-ray modulation type':
            event.xray_modulation_type = cont.TextValue
        if cont.ConceptNameCodeSequence[0].CodeMeaning == 'Comment':
            event.comment = cont.TextValue
    if not event.xray_modulation_type and event.comment:
        comments = event.comment.split(",")
        for comm in comments:
            if comm.lstrip().startswith("X-ray Modulation Type"):
                modulationtype = comm[(comm.find('=')+2):]
                event.xray_modulation_type = modulationtype

but the word "modulation" doesn't seem to be present in either the Siemens or Philips dose report...

[Ed McDonagh]

It does in mine (Siemens). Were you searching for modulation and not finding Modulation? It is in the comment field.

[David Platten]

It looks like there should be a code 113842 that contains the modulation type (ftp://medical.nema.org/medical/dicom/final/cp957_ft2.pdf), but this code doesn't exist in either report, so it can't be that.

[David Platten]

I've done a dcmdump to a text file for a Siemens report and a Philips one, and am looking at the text files in an editor. Can't see the word "Modulation" in either. Perhaps the dcmdump doesn't dump everything out?

Do you have a Philips CT system with AEC talking to OpenREM? If so, can you see the info about AEC in ctdetail.html?

[Ed McDonagh]

I've just looked using dcmdump and the comment field is abbreviated. Using gdcmdump, you get the following:

(fffe,e000) na (Item with undefined length)
        (0040,a010) CS [CONTAINS]                                 # 8,1 Relationship Type
        (0040,a040) CS [TEXT]                                     # 4,1 Value Type
        (0040,a043) SQ (Sequence with undefined length)           # u/l,1 Concept Name Code Sequence
          (fffe,e000) na (Item with undefined length)
            (0008,0100) SH [121106]                               # 6,1 Code Value
            (0008,0102) SH [DCM ]                                 # 4,1 Coding Scheme Designator
            (0008,0104) LO [Comment ]                             # 8,1 Code Meaning
          (fffe,e00d)
        (fffe,e0dd)
        (0040,a160) UT [Internal technical scan parameters: Organ Characteristic = Abdomen, Body Size = Adult, Body Region = Body, X-ray Modulation Type = OFF]         # 134,1 Text Value
      (fffe,e00d)

[Ed McDonagh]

I'd point you to the grassroots DICOM page, but it is on sourceforge which seems to be down :-(

However, a quick sudo apt-get install libgdcm-tools on Ubuntu would have you up and running ;-)

[David Platten]

Thanks - I'll have a look tomorrow.

[David Platten]

Excellent: gdcmdump shows that the Siemens rdsr does indeed have text relating to AEC use.

Not so good: there's nothing in the Philips rdsr about AEC use (or iDose).

[David Platten]

It's not going to be possible to resolve this issue as the Philips structured dose report does not include any information about the AEC.

[David Platten]

It's not going to be possible to resolve this issue as the Philips structured dose report does not include any information about the AEC.