Acquisition Time Tag question - DICOM

This is a discussion on Acquisition Time Tag question - DICOM ; Hi, The DICOM tag Acquisition Time (0008 0032) - is this the time the whole series was taken? Or is it unique per image in the series? If for the whole series, does it represent the *start* time, the time ...

+ Reply to Thread
Results 1 to 12 of 12

Thread: Acquisition Time Tag question

  1. Acquisition Time Tag question

    Hi,

    The DICOM tag Acquisition Time (0008 0032) - is this the time the whole
    series was taken? Or is it unique per image in the series?

    If for the whole series, does it represent the *start* time, the time
    the first image was taken? Or does it represent some other time in the
    series?
    Is there some master list with all tag definitions?

    Thanks!
    Mark


  2. Re: Acquisition Time Tag question

    Hi Mark.

    The Aquisition Time represents the time at which the image was aquired
    and it is part of the General Image Module... See PS 3.3,Annex C.7.6
    The study and series both have their own time identification in the
    tags Series Date/Time - General Series Module - PS.3.3 C.7.3.1 and
    Study Date/Time in General Study Module - P.S. 3.3.C.7.2.1

    ~~Razvan


  3. Re: Acquisition Time Tag question


    markww wrote:
    > Hi,
    >
    > The DICOM tag Acquisition Time (0008 0032) - is this the time the

    whole
    > series was taken? Or is it unique per image in the series?
    >
    > If for the whole series, does it represent the *start* time, the time
    > the first image was taken? Or does it represent some other time in

    the
    > series?
    > Is there some master list with all tag definitions?
    >
    > Thanks!
    > Mark



  4. Re: Acquisition Time Tag question

    Hi...

    Aquisition Time is the time when the _image_ was aquired. It is part of
    the General Image module; it is also part of PET Image modules.

    Study date/time, series date/time have separate tags and are also
    present in their respective modules - Study/Series General Module.
    Modules are groups of rules that specify which attributes should be
    present in which contexts.

    You can find the tables you are looking for (tables which describe the
    modules) in PS 3.3, annex C.
    The complete list of tags is part of PS 3.6.

    HTH,
    ~~Razvan


  5. Re: Acquisition Time Tag question

    Hi,

    How is Content Time different from Aquisition Time?

    Regards,
    SJ


    "Razvan Costea-Barlutiu" wrote in message
    news:1106898368.734347.226730@z14g2000cwz.googlegr oups.com...
    > Hi...
    >
    > Aquisition Time is the time when the _image_ was aquired. It is part of
    > the General Image module; it is also part of PET Image modules.
    >
    > Study date/time, series date/time have separate tags and are also
    > present in their respective modules - Study/Series General Module.
    > Modules are groups of rules that specify which attributes should be
    > present in which contexts.
    >
    > You can find the tables you are looking for (tables which describe the
    > modules) in PS 3.3, annex C.
    > The complete list of tags is part of PS 3.6.
    >
    > HTH,
    > ~~Razvan
    >




  6. Re: Acquisition Time Tag question

    Jain,

    My understanding of this, after reading the P.S. 3.3. is that the
    Aquisition Time is the time at which the raw image data started to be
    aquired (that is, before actual data-pixel transformation) whereas the
    Content time would be the time at which the pixel-data was created
    (stored?), which can/should be different from the Aquisition time,
    given the processing and actual aquisition time involved.

    Both the Content Time and Acquisition Time, (as other xxxTime tags in
    the IODs) represent temporal references to the beginning of an alleged
    data-intensive and time-consuming process.

    So, I see this as:

    ::StartAcquiring[Acq-Time]--->Acquiring--->::StartStoring[ContentTime]-->Storing.


    HTH
    ~~Razvan


  7. Group Order (ascending?)

    I have a MRI scanner that just started sending the groups out of
    ascending order. I always thought that the groups (and elements?) need
    to come in ascending order. Is that incorrect?

    On this particular scanner, it is now sending group 40(hex) after group
    FFFE. Is this valid? If groups need to come in ascending order, are
    elements supposed to be in ascending order as well .. or can they
    (groups and elements) come in any order?

    Thanks,
    Bruce

  8. Acquisition Time Tag question

    Bruce wrote:
    > I have a MRI scanner that just started sending the groups out of
    > ascending order. I always thought that the groups (and elements?)

    need
    > to come in ascending order. Is that incorrect?
    >
    > On this particular scanner, it is now sending group 40(hex) after

    group
    > FFFE. Is this valid? If groups need to come in ascending order, are
    > elements supposed to be in ascending order as well .. or can they
    > (groups and elements) come in any order?
    >
    > Thanks,
    > Bruce



    Bruce,

    FFFE is part of the item tag and I think that what you see there is a
    sequence. Within a sequence, your elements would still be ordered, but
    relative to the sequence itself, not to the whole IOD, you can't do
    that.

    Isn't there a VR=SQ just before the FFFE you think it is faulty?

    HTH
    ~~Razvan
    P.S. You should have started a new thread for this.


  9. Acquisition Time Tag question

    > FFFE is part of the item tag and I think that what you see there is a
    > sequence. Within a sequence, your elements would still be ordered,

    but
    > relative to the sequence itself, not to the whole IOD, you can't do
    > that.


    Ooops, I meant, the elements would be ordered relative to the _item_
    itself (not the sequence). Direct children of an item are ordered and
    this rule applies recursively on nested items.

    ~~Razvan


  10. Re: Group Order (ascending?)

    Bruce wrote in message news:...
    > I have a MRI scanner that just started sending the groups out of
    > ascending order. I always thought that the groups (and elements?) need
    > to come in ascending order. Is that incorrect?
    >
    > On this particular scanner, it is now sending group 40(hex) after group
    > FFFE. Is this valid? If groups need to come in ascending order, are
    > elements supposed to be in ascending order as well .. or can they
    > (groups and elements) come in any order?
    >
    > Thanks,
    > Bruce


    Dear Bruce,

    within a single command set or data set, the command elements and data
    elements MUST be in ascending tag order (group number AND element
    number). I believe a modality which doesn't send data elements or
    command elements in ascending tag order is not fully DICOM-conformant.
    In any case, many DICOM protocol implementations also accepts
    unordered DICOM data sets, in order to be able to communicate with
    modalities which have these "ordering" problems.

    Hope it helps,

    Marco.

  11. Acquisition Time Tag question

    > Dear Bruce,
    >
    > within a single command set or data set, the command elements and

    data
    > elements MUST be in ascending tag order (group number AND element
    > number). I believe a modality which doesn't send data elements or
    > command elements in ascending tag order is not fully

    DICOM-conformant.
    > In any case, many DICOM protocol implementations also accepts
    > unordered DICOM data sets, in order to be able to communicate with
    > modalities which have these "ordering" problems.
    >
    > Hope it helps,
    >
    > Marco.


    Marco~~

    I believe that by "Single [...] dataset" you imply also "flat" dataset,
    with no nested items, for which your statement above is generally true.

    Tags can seem out of order when they are present inside items in
    sequences and you're reading the dataset as a flat list.

    For instance, you'd get a similar feeling browsing an SR report dump.
    You can simply have repeating items occuring inside sequence items like
    the observation date/time which can appear countless times in an such
    an IOD.

    There is no possible way to enforce dataset-absolute tag ordering when
    nesting is allowed.

    The ordering of the dataset is local, meaning that
    - the top-level tags must occur in ascending group/element order.
    - tags appearing in an item must occur in ascending group/element
    order.

    You can find this in PS 3.5, section 7.5.

    ~~Razvan


  12. Re: Acquisition Time Tag question

    Yes, Razvan is right, I'm sorry not to have mentioned this: data
    elements inside Items belonging to a Sequence of Items must be
    "locally ordered" (i.e., within the same Item), but you can't expect a
    "global" data elements ordering if you see a nested data set in a flat
    way.

    Hope it helps.

    Regards,

    Marco.

+ Reply to Thread