Hercules Dev. wrote:
> I'm trying to implement a MPPS server, so i'm studying the attributes
> of the MPPS SOP so i can find what i need to support and how the data
> representation will be, i already implemented a MWL SCU and now i'm
> trying to integrate between the two SOPs.
>
> The problem is with the Referenced Study Sequence (0008,1110) under the
> Performed Procedure Step Relationship Module, the standard says in PS
> 3.3 Table C.4-13 that this sequence shall have only one item, but when
> you search on how the standard and the IHE tells you to fill this
> sequence you find that you should copy its value from the Requested
> Procedure Module in the MWL SOP, but this sequence there is mlti-item
> so how can this be?
>
> refer to DICOM PS 3.17 section J.4.1

seems my question is not so clear, ok here it is again in a simple way:
Is the Referenced Study Sequence (0008,1110) under the Performed
Procedure Step Relationship Module a single item sequence or a
multi-item sequence?

Now, if it's a single item sequence how the SCU will send it to me in
the MPPS N-CREATE if the Requested Procedure has multi item in its
Referenced Study Sequence (0008,1110) ?

and if it is multi-item then why the DICOM standard says its a single
item in PS 3.3 Table C.4-13 ?

All references to the DICOM or IHE are from the latest version.

Thanks
Zaid H. Safadi

So does this mean that no body know the answer or that it's a very
straight forward and trivial??!!!

Hercules Dev. wrote:
> Hercules Dev. wrote:
> > I'm trying to implement a MPPS server, so i'm studying the attributes
> > of the MPPS SOP so i can find what i need to support and how the data
> > representation will be, i already implemented a MWL SCU and now i'm
> > trying to integrate between the two SOPs.
> >
> > The problem is with the Referenced Study Sequence (0008,1110) under the
> > Performed Procedure Step Relationship Module, the standard says in PS
> > 3.3 Table C.4-13 that this sequence shall have only one item, but when
> > you search on how the standard and the IHE tells you to fill this
> > sequence you find that you should copy its value from the Requested
> > Procedure Module in the MWL SOP, but this sequence there is mlti-item
> > so how can this be?
> >
> > refer to DICOM PS 3.17 section J.4.1
>
> seems my question is not so clear, ok here it is again in a simple way:
> Is the Referenced Study Sequence (0008,1110) under the Performed
> Procedure Step Relationship Module a single item sequence or a
> multi-item sequence?
>
> Now, if it's a single item sequence how the SCU will send it to me in
> the MPPS N-CREATE if the Requested Procedure has multi item in its
> Referenced Study Sequence (0008,1110) ?
>
> and if it is multi-item then why the DICOM standard says its a single
> item in PS 3.3 Table C.4-13 ?
>
> All references to the DICOM or IHE are from the latest version.
>
> Thanks
> Zaid H. Safadi

Hi Zaid

The bottom line is that since the cardinality of Referenced
Study Sequence in the MPPS definition is limited to no more
than one, you cannot ever send more than one; so you
have to decide which one to send if there is a choice,
or find another way.

Since the Referenced Study Sequence occurs inside an item
of the Scheduled Step Attributes Sequence, which may have
multiple items, the problem only occurs when the scheduled
step in the MWL contains multiple items in Referenced Study
Sequence, and not when one PPS is being performed to satisfy
multiple SPS, because in that case there would be more than
one Scheduled Step Attributes Sequence, each still containing
a Referenced Study Sequence with a single item.

As far as IHE is concerned, in the Query Modality Worklist
transaction, it specifies that "the Referenced Study Sequence
shall contain only one Referenced SOP Class UID and one
Referenced SOP Instance UID for each Scheduled Procedure
Step" (see IHE Rad TF Vol 2 4.5.4.1.2.2), so there is only
going to be one item to copy (regardless of what DICOM
permits).

So your own MWL implementation should probably enforce this
IHE restriction.

If you encounter another MWL implementation, and it is not
IHE compliant in this respect, then you will have to make
a choice, or send multiple Scheduled Step Attributes Sequence
items that are identical apart from different Referenced Study
Sequence entries (not sure if that is such a cool idea either).

But you should NEVER send more than one item in the Referenced
Study Sequence inside the Scheduled Step Attributes Sequence,
since that is explicitly forbidden (I don't recall why it
was decided that it be this way).

David

Hercules Dev. wrote:
> Hercules Dev. wrote:
>> I'm trying to implement a MPPS server, so i'm studying the attributes
>> of the MPPS SOP so i can find what i need to support and how the data
>> representation will be, i already implemented a MWL SCU and now i'm
>> trying to integrate between the two SOPs.
>>
>> The problem is with the Referenced Study Sequence (0008,1110) under the
>> Performed Procedure Step Relationship Module, the standard says in PS
>> 3.3 Table C.4-13 that this sequence shall have only one item, but when
>> you search on how the standard and the IHE tells you to fill this
>> sequence you find that you should copy its value from the Requested
>> Procedure Module in the MWL SOP, but this sequence there is mlti-item
>> so how can this be?
>>
>> refer to DICOM PS 3.17 section J.4.1
>
> seems my question is not so clear, ok here it is again in a simple way:
> Is the Referenced Study Sequence (0008,1110) under the Performed
> Procedure Step Relationship Module a single item sequence or a
> multi-item sequence?
>
> Now, if it's a single item sequence how the SCU will send it to me in
> the MPPS N-CREATE if the Requested Procedure has multi item in its
> Referenced Study Sequence (0008,1110) ?
>
> and if it is multi-item then why the DICOM standard says its a single
> item in PS 3.3 Table C.4-13 ?
>
> All references to the DICOM or IHE are from the latest version.
>
> Thanks
> Zaid H. Safadi
>

Thanks MR. Cluni for your reply to my question, and from your answer I
figured that it was a valid and important question.

So there is no way to send this sequence as a multi-item, and it should
always be sent with one referenced study, so if a multi item referenced
study sequence exist in a work-list either the SCU select one of them
or send each item in a different Scheduled Step Attribute Sequence item
with same SPS information.

So in the case of a MPPS SCP, it should not accept a Referenced Study
Sequence with multi-item, even though it can perform matching for this
sequence with the original MWL Referenced Study Sequence ( in case the
MPPS and MWL SCPs uses the same data store).

As for my implementing a MPPS SCP is it legal if I relaxed this rule
and ignored the fact that I received this sequence as multi-item
especially that I won't store it and only will be used for matching?

And if there is a necessity for a MPPS SCU to send this sequence as a
multi-item -which is the logical behavior in our case- why the standard
don't allow this sequence to be multi-item?

Thanks,
Zaid H. Safadi

David Clunie wrote:
> Hi Zaid
>
> The bottom line is that since the cardinality of Referenced
> Study Sequence in the MPPS definition is limited to no more
> than one, you cannot ever send more than one; so you
> have to decide which one to send if there is a choice,
> or find another way.
>
> Since the Referenced Study Sequence occurs inside an item
> of the Scheduled Step Attributes Sequence, which may have
> multiple items, the problem only occurs when the scheduled
> step in the MWL contains multiple items in Referenced Study
> Sequence, and not when one PPS is being performed to satisfy
> multiple SPS, because in that case there would be more than
> one Scheduled Step Attributes Sequence, each still containing
> a Referenced Study Sequence with a single item.
>
> As far as IHE is concerned, in the Query Modality Worklist
> transaction, it specifies that "the Referenced Study Sequence
> shall contain only one Referenced SOP Class UID and one
> Referenced SOP Instance UID for each Scheduled Procedure
> Step" (see IHE Rad TF Vol 2 4.5.4.1.2.2), so there is only
> going to be one item to copy (regardless of what DICOM
> permits).
>
> So your own MWL implementation should probably enforce this
> IHE restriction.
>
> If you encounter another MWL implementation, and it is not
> IHE compliant in this respect, then you will have to make
> a choice, or send multiple Scheduled Step Attributes Sequence
> items that are identical apart from different Referenced Study
> Sequence entries (not sure if that is such a cool idea either).
>
> But you should NEVER send more than one item in the Referenced
> Study Sequence inside the Scheduled Step Attributes Sequence,
> since that is explicitly forbidden (I don't recall why it
> was decided that it be this way).
>
> David
>
> Hercules Dev. wrote:
> > Hercules Dev. wrote:
> >> I'm trying to implement a MPPS server, so i'm studying the attributes
> >> of the MPPS SOP so i can find what i need to support and how the data
> >> representation will be, i already implemented a MWL SCU and now i'm
> >> trying to integrate between the two SOPs.
> >>
> >> The problem is with the Referenced Study Sequence (0008,1110) under the
> >> Performed Procedure Step Relationship Module, the standard says in PS
> >> 3.3 Table C.4-13 that this sequence shall have only one item, but when
> >> you search on how the standard and the IHE tells you to fill this
> >> sequence you find that you should copy its value from the Requested
> >> Procedure Module in the MWL SOP, but this sequence there is mlti-item
> >> so how can this be?
> >>
> >> refer to DICOM PS 3.17 section J.4.1
> >
> > seems my question is not so clear, ok here it is again in a simple way:
> > Is the Referenced Study Sequence (0008,1110) under the Performed
> > Procedure Step Relationship Module a single item sequence or a
> > multi-item sequence?
> >
> > Now, if it's a single item sequence how the SCU will send it to me in
> > the MPPS N-CREATE if the Requested Procedure has multi item in its
> > Referenced Study Sequence (0008,1110) ?
> >
> > and if it is multi-item then why the DICOM standard says its a single
> > item in PS 3.3 Table C.4-13 ?
> >
> > All references to the DICOM or IHE are from the latest version.
> >
> > Thanks
> > Zaid H. Safadi
> >