DICOM Worklists questions

Hi All,
I'm trying to learn about worklists and PACS, but unfortunately I'm not able
to look how it works in real life. Maybe some questions I have are 'stupid',
so please be patient and forbearing... Could someone explain me process of
handling worklist?
I would like to know:
1) Do woklists are handled by part of PACS system?
1) Is worklist always sent to the device only in response to modality's
request? How modality is asking about it?
2) How a task from current worklist is marked as 'done' after doing some
studies by using modality - which component is responsible of removing tasks
from worklist? Maybe it has to be done in manual way? What makes study
recognizable as 'a response' of task given in worklist?
3) When modality is asking system about current worklist the request can
have parameters. Am I right? If yes, what it can be?
4) If modality requests of worklist for more than one time in short period
of time, the response always contain all records of worklist or only portion
of data which is a difference from last response?

Thanks in advance for Your response :)
Maciek

Macias wrote:[color=blue]
> 1) Do woklists are handled by part of PACS system?[/color]

The DICOM standard does not specify which system implements which
service, but typically the worklist is provided by the RIS and retrieved
by the modality, without any direct involvement of the PACS.
[color=blue]
> 1) Is worklist always sent to the device only in response to modality's
> request? How modality is asking about it?[/color]

The modality has to request a worklist using the Modality Worklist
Service Class. Basically, it sends a C-FIND-RQ message to the server
and receives one or more C-FIND-RSP messages in response.
[color=blue]
> 2) How a task from current worklist is marked as 'done' after doing some
> studies by using modality - which component is responsible of removing tasks
> from worklist? Maybe it has to be done in manual way? What makes study
> recognizable as 'a response' of task given in worklist?[/color]

This can be implemented through the MPPS (Modality Performed Procedure
Step) SOP Class which allows the modality to register performed
procedure steps in relationship to the scheduled procedure steps from
the worklist. Some worklist identifiers (such as the scheduled procedure
step ID which identifies the worklist entry) can also be stored in the
image header in some sequences, but this is optional.
[color=blue]
> 3) When modality is asking system about current worklist the request can
> have parameters. Am I right? If yes, what it can be?[/color]

Basically the modality sends a query that specifies which attributes the
modality is interested in and that can also contain filtering
information (such as: I am only interested in worklist entries for the
modality "CR" or for the system with the aetitle "CR_IN_ROOM_100").
[color=blue]
> 4) If modality requests of worklist for more than one time in short period
> of time, the response always contain all records of worklist or only portion
> of data which is a difference from last response?[/color]

The response always contains all worklist entries that match the query,
no matter whether they are retrieved for the first time or not.

Regards,
Marco Eichelberg

HI,
Is it must that MWL and MPPS should be on same SCP, if not how RIS
removes worklist which is already completed once after modalaity
sending MPPS-SET with status as COMPLETED. Are there any incidents that
RIS will still have worklist entries even after particluar worklist is
fetched by modality and finished that study(worklist).

Cheers...

PS: Iam pushing images to PACS(storage service). Should MPPS service
need to send to PACS now..

Marco Eichelberg wrote:[color=blue]
> Macias wrote:[color=green]
> > 1) Do woklists are handled by part of PACS system?[/color]
>
> The DICOM standard does not specify which system implements which
> service, but typically the worklist is provided by the RIS and retrieved
> by the modality, without any direct involvement of the PACS.
>[color=green]
> > 1) Is worklist always sent to the device only in response to modality's
> > request? How modality is asking about it?[/color]
>
> The modality has to request a worklist using the Modality Worklist
> Service Class. Basically, it sends a C-FIND-RQ message to the server
> and receives one or more C-FIND-RSP messages in response.
>[color=green]
> > 2) How a task from current worklist is marked as 'done' after doing some
> > studies by using modality - which component is responsible of removing tasks
> > from worklist? Maybe it has to be done in manual way? What makes study
> > recognizable as 'a response' of task given in worklist?[/color]
>
> This can be implemented through the MPPS (Modality Performed Procedure
> Step) SOP Class which allows the modality to register performed
> procedure steps in relationship to the scheduled procedure steps from
> the worklist. Some worklist identifiers (such as the scheduled procedure
> step ID which identifies the worklist entry) can also be stored in the
> image header in some sequences, but this is optional.
>[color=green]
> > 3) When modality is asking system about current worklist the request can
> > have parameters. Am I right? If yes, what it can be?[/color]
>
> Basically the modality sends a query that specifies which attributes the
> modality is interested in and that can also contain filtering
> information (such as: I am only interested in worklist entries for the
> modality "CR" or for the system with the aetitle "CR_IN_ROOM_100").
>[color=green]
> > 4) If modality requests of worklist for more than one time in short period
> > of time, the response always contain all records of worklist or only portion
> > of data which is a difference from last response?[/color]
>
> The response always contains all worklist entries that match the query,
> no matter whether they are retrieved for the first time or not.
>
> Regards,
> Marco Eichelberg[/color]

Radde wrote:[color=blue]
> Is it must that MWL and MPPS should be on same SCP, if not how RIS
> removes worklist which is already completed once after modalaity
> sending MPPS-SET with status as COMPLETED.[/color]

At least this is the normal case, i.e. MPPS going to the RIS.
The IHE Technical Framework describes an entity (actor) named
"PPS manager" that would forward one MPPS message to multiple
recipients, enabling MPPS information to be available both at the
RIS and the PACS.

You should also note that most RIS systems will not automatically
remove worklist entries once a corresponding MPPS has been completed -
the operator of the modality may well have just selected the wrong
worklist entry and pressed the wrong button, this just happens.
Therefore, many systems will require a manual confirmation at the RIS
or only remove the worklist entry once the report is written.

Regards,
Marco Eichelberg

Thank you marco..You are right. Now iam assuming that modality itself
act as PPS manager.

You should also note that most RIS systems will not automatically[color=blue]
> remove worklist entries once a corresponding MPPS has been completed -
> the operator of the modality may well have just selected the wrong
> worklist entry and pressed the wrong button, this just happens.
> Therefore, many systems will require a manual confirmation at the RIS
> or only remove the worklist entry once the report is written.[/color]

How will the modality know that particular worklist(done through)
is removed from RIS. If RIS doesnt remove that worklist, in case if
modality queries for the same worklist which is already done, it
results repeated SPS(PPS). How this is avoided or how to avoid this
situation.

Cheers..


Marco Eichelberg wrote:[color=blue]
> Radde wrote:[color=green]
> > Is it must that MWL and MPPS should be on same SCP, if not how RIS
> > removes worklist which is already completed once after modalaity
> > sending MPPS-SET with status as COMPLETED.[/color]
>
> At least this is the normal case, i.e. MPPS going to the RIS.
> The IHE Technical Framework describes an entity (actor) named
> "PPS manager" that would forward one MPPS message to multiple
> recipients, enabling MPPS information to be available both at the
> RIS and the PACS.
>
> You should also note that most RIS systems will not automatically
> remove worklist entries once a corresponding MPPS has been completed -
> the operator of the modality may well have just selected the wrong
> worklist entry and pressed the wrong button, this just happens.
> Therefore, many systems will require a manual confirmation at the RIS
> or only remove the worklist entry once the report is written.
>
> Regards,
> Marco Eichelberg[/color]

Macias,

for a beginer in DICOM, this book on DICOM might be useful:
[url]http://www.otechimg.com/pub_dicom.php?menu=pubs[/url]

Herman O.

Macias wrote:[color=blue]
> Hi All,
> I'm trying to learn about worklists and PACS, but unfortunately I'm not able
> to look how it works in real life. Maybe some questions I have are 'stupid',
> so please be patient and forbearing... Could someone explain me process of
> handling worklist?
> I would like to know:
> 1) Do woklists are handled by part of PACS system?
> 1) Is worklist always sent to the device only in response to modality's
> request? How modality is asking about it?
> 2) How a task from current worklist is marked as 'done' after doing some
> studies by using modality - which component is responsible of removing tasks
> from worklist? Maybe it has to be done in manual way? What makes study
> recognizable as 'a response' of task given in worklist?
> 3) When modality is asking system about current worklist the request can
> have parameters. Am I right? If yes, what it can be?
> 4) If modality requests of worklist for more than one time in short period
> of time, the response always contain all records of worklist or only portion
> of data which is a difference from last response?
>
> Thanks in advance for Your response :)
> Maciek[/color]