Unique tag within a dicom file - DICOM

This is a discussion on Unique tag within a dicom file - DICOM ; Hello, I am a bit confused. I thought that a group + element, would give me a unique key to a Tag. But this isn't true within a sequence. Is there a 'general' key to identify a dicom value, within ...

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  1. Unique tag within a dicom file

    Hello,

    I am a bit confused. I thought that a group + element, would give me a
    unique key to a Tag. But this isn't true within a sequence. Is there a
    'general' key to identify a dicom value, within or not a sequence.

    Thanks
    Mathieu


  2. Re: Unique tag within a dicom file

    Hi, Mathieu -

    No, there is no "general" key to identify a particular DICOM attribute
    within DICOM Data Set (both DICOM messages and DICOM files contain Data Sets
    augmented by some additional information).

    On the top level of Data Set you can only "uniquely identify an attribute
    which may or may not be a sequence. In the latter case, the value of the
    attribute is in fact one or more Data Sets, and you have to parse them
    exactly the same way you did the Top level Data Set. And these Data Sets can
    in turn contain sequences containing Data Sets ad infinitum. DICOM SR
    objects are especially notorious about it.

    In other words, you should not consider the structure of DICOM Data Set as
    flat where every element can be accessed directly, via offset, "unique key"
    or any other mechanism, but rather as a tree where you have to navigate from
    one node to another until you reach the leaf node. So, it is not enough to
    know the tag of particular element, but also tags of all sequences it is
    included into, i.e., path from the root to the leaf node.

    Andrei

    On 11/9/04 3:04 PM, in article wp9kd.375974$bp1.366155@twister.nyroc.rr.com,
    "Mathieu Malaterre" wrote:

    > Hello,
    >
    > I am a bit confused. I thought that a group + element, would give me a
    > unique key to a Tag. But this isn't true within a sequence. Is there a
    > 'general' key to identify a dicom value, within or not a sequence.
    >
    > Thanks
    > Mathieu
    >



  3. Re: Unique tag within a dicom file

    Thanks for the detailed answer.

    I'll have to rework my stuff then.

    Andrei Leontiev wrote:
    > Hi, Mathieu -
    >
    > No, there is no "general" key to identify a particular DICOM attribute
    > within DICOM Data Set (both DICOM messages and DICOM files contain Data Sets
    > augmented by some additional information).
    >
    > On the top level of Data Set you can only "uniquely identify an attribute
    > which may or may not be a sequence. In the latter case, the value of the
    > attribute is in fact one or more Data Sets, and you have to parse them
    > exactly the same way you did the Top level Data Set. And these Data Sets can
    > in turn contain sequences containing Data Sets ad infinitum. DICOM SR
    > objects are especially notorious about it.
    >
    > In other words, you should not consider the structure of DICOM Data Set as
    > flat where every element can be accessed directly, via offset, "unique key"
    > or any other mechanism, but rather as a tree where you have to navigate from
    > one node to another until you reach the leaf node. So, it is not enough to
    > know the tag of particular element, but also tags of all sequences it is
    > included into, i.e., path from the root to the leaf node.
    >
    > Andrei
    >
    > On 11/9/04 3:04 PM, in article wp9kd.375974$bp1.366155@twister.nyroc.rr.com,
    > "Mathieu Malaterre" wrote:
    >
    >
    >>Hello,
    >>
    >>I am a bit confused. I thought that a group + element, would give me a
    >>unique key to a Tag. But this isn't true within a sequence. Is there a
    >>'general' key to identify a dicom value, within or not a sequence.
    >>
    >>Thanks
    >>Mathieu
    >>

    >
    >



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