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  • Proposing MPEG2 transfer syntax for storing images?

    From Silvia Winkler@21:1/5 to All on Tue Mar 9 07:40:18 2021
    I came across a DICOM conformance statement of a PACS that seems to also propose MPEG2 transfer syntax for image SOP classes like CR Image Storage , CT Image Storage, ...
    Are there any rules in the DICOM standard that define which transfer syntaxes may be proposed for a SOP class?
    What could be the reason to propose CT Image Storage SOP class with an MPEG2 transfer syntax? When would this make sense?

    Best,
    Silvia

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  • From David Clunie@21:1/5 to Herman Oosterwijk on Wed Mar 10 06:45:56 2021
    On 3/10/21 9:17 AM, Herman Oosterwijk wrote:

    There are no rules except for the requirement that every device has to support the default transfer syntax (ILE).

    Except when the original is only available in lossy compressed form, or is of such a length that it does not fit:

    http://dicom.nema.org/medical/dicom/current/output/chtml/part05/chapter_10.html#sect_10.1

    David

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  • From Herman Oosterwijk@21:1/5 to Silvia Winkler on Wed Mar 10 06:17:29 2021
    On Tuesday, March 9, 2021 at 9:40:20 AM UTC-6, Silvia Winkler wrote:

    Are there any rules in the DICOM standard that define which transfer syntaxes may be proposed for a SOP class?
    What could be the reason to propose CT Image Storage SOP class with an MPEG2 transfer syntax? When would this make sense?

    There are no rules except for the requirement that every device has to support the default transfer syntax (ILE).

    I have seen "weird" transfer syntaxes more often. It appears that vendors cut/paste these capabilities from their DICOM toolkit capabilities without giving it any thought. From a software quality perspective this is actually a liability as one could
    argue that a vendor has to prove/test that his product performs according to his interface spec and I wouldn't know how to get a hold of a MPEG2 encoded CT to perform this testing. (BTW, MPEG4 would be better than MPEG2).

    It could be of course that they create a 3-D reconstruction and rotate it and store it as a MPEG2 clip and re-create a CT SOP Class, but in that case it should really be a SC as many of the required attributes such as slice thickness do not make sense.

    Herman O.

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  • From Silvia Winkler@21:1/5 to All on Wed Mar 17 01:55:26 2021
    Thank you for your comments!
    I contacted the manufacturer to inquire about their reason for using MPEG2.
    If there is any significant reason for this, I'll post this here on this thread.

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