Problem with DICOMDIR syntax - DICOM

This is a discussion on Problem with DICOMDIR syntax - DICOM ; Bonjour, I am putting the finishing touch to a small free application that will create DICOMDIR files. The idea is to create a DICOMDIR for all the part-10 files present in a directory tree. The user just drag&drop the root ...

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Thread: Problem with DICOMDIR syntax

  1. Problem with DICOMDIR syntax

    Bonjour,

    I am putting the finishing touch to a small free application that will
    create DICOMDIR files.

    The idea is to create a DICOMDIR for all the part-10 files present in
    a directory tree. The user just drag&drop the root folder on the
    application and it will add the DICOMDIR in the folder.

    There is also a small ".ini" file where the user can specify the tags
    he wants to see in the [PATIENT], [STUDY], [SERIES] and [IMAGE]
    section.

    I have 2 problems with the "Reference File ID" (0004,1500) tag:

    Problem 1:

    - The file name and directories are limited to 8 characters each from
    the VR=CS character set!

    David, you where there when the DICOMDIR was created? Can you
    remember the logic behind that choice? I can understand wanting to
    use the lowest common denominator, but the DICOMDIR is not that old!?!
    Surely, all operating systems where supporting extensions at that
    time? And even DOS had extended file name...

    I need extensions for my DICOM files! I place them in the same
    directory as original (non-DICOM) images and only the extension can
    differentiate them.

    So unless I have the application refuse to create a DICOMDIR for most
    of the directory structures, I see only one way out of this: use a
    different VR if the file name does not fit in the CS character set.

    I know, I know, everybody will fall on my head, my DICOMDIR will not
    respect the standard. But, the VR is explicit, so how many
    application will actually fail if I use SH or even LO?

    Problem 2:

    - The standard say: "Any File within the File-set (to which the
    Directory belongs) shall be referenced by at most one Directory
    Record."

    I understand this as meaning that a file can only be referenced once
    in the DICOMDIR. Is this correct?

    If this is the correct interpretation, then how do I reference (for
    example) an enhance MR that contains multiple images? I place the
    file reference with the series? But what if that series is actually
    split among 2 files? Or if I have images from 2 series in the file?

    Anybody has ideas, suggestions?

    Merci,
    Yves




  2. Re: Problem with DICOMDIR syntax

    Hi Yves

    Regardless of what you want to do, the standard is the standard, and
    yes, extensions and > 8 bit file names are absolutely prohibited. Get
    over it and stop whining.

    I wasn't around then, so I have no idea why the restriction was imposed
    or why the CS VR was chosen.

    If you can't distinguish original and DICOM files in the same directory
    except by extension, put them in separate directories. Or assume that
    the ones without the extensions are the DICOM files.

    DO NOT USE ILLEGAL VRs IN DICOMDIRs.

    DO NOT CREATE INVALID DICOMDIRs.

    I will be really pissed off if someone like you, who knows better,
    deliberately violates the standard just because it is convenient.

    The IMAGE directory record is used to reference the entire multi-frame
    file, in the case of Enhanced CT and MR, or old XA/XRF or Multi-frame
    US, for example. A multi-frame DICOM image contains one "image" from
    a DICOM perspective.

    There are NEVER file references at the SERIES level.

    David

    PS. If you have a file system that can support hard or symbolic links,
    it is possible to share the same file content between two filenames,
    one with extensions for your nefarious purposes, and one without to
    be referenced from the DICOMDIR.

    Yves Martel wrote:
    > Bonjour,
    >
    > I am putting the finishing touch to a small free application that will
    > create DICOMDIR files.
    >
    > The idea is to create a DICOMDIR for all the part-10 files present in
    > a directory tree. The user just drag&drop the root folder on the
    > application and it will add the DICOMDIR in the folder.
    >
    > There is also a small ".ini" file where the user can specify the tags
    > he wants to see in the [PATIENT], [STUDY], [SERIES] and [IMAGE]
    > section.
    >
    > I have 2 problems with the "Reference File ID" (0004,1500) tag:
    >
    > Problem 1:
    >
    > - The file name and directories are limited to 8 characters each from
    > the VR=CS character set!
    >
    > David, you where there when the DICOMDIR was created? Can you
    > remember the logic behind that choice? I can understand wanting to
    > use the lowest common denominator, but the DICOMDIR is not that old!?!
    > Surely, all operating systems where supporting extensions at that
    > time? And even DOS had extended file name...
    >
    > I need extensions for my DICOM files! I place them in the same
    > directory as original (non-DICOM) images and only the extension can
    > differentiate them.
    >
    > So unless I have the application refuse to create a DICOMDIR for most
    > of the directory structures, I see only one way out of this: use a
    > different VR if the file name does not fit in the CS character set.
    >
    > I know, I know, everybody will fall on my head, my DICOMDIR will not
    > respect the standard. But, the VR is explicit, so how many
    > application will actually fail if I use SH or even LO?
    >
    > Problem 2:
    >
    > - The standard say: "Any File within the File-set (to which the
    > Directory belongs) shall be referenced by at most one Directory
    > Record."
    >
    > I understand this as meaning that a file can only be referenced once
    > in the DICOMDIR. Is this correct?
    >
    > If this is the correct interpretation, then how do I reference (for
    > example) an enhance MR that contains multiple images? I place the
    > file reference with the series? But what if that series is actually
    > split among 2 files? Or if I have images from 2 series in the file?
    >
    > Anybody has ideas, suggestions?
    >
    > Merci,
    > Yves
    >
    >
    >


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