Flexible Workflow using UPS: Unified Procedure Step

1. Flexible Workflow using
UPS:
Unified Procedure Step
Kevin O’Donnell
Toshiba Medical Systems

2. UPS Goals
 Add “Push Workflow” & “Create Workitem”
– Request another system to add item to worklist
 Simplify Implementation
– GPWL had N:M relation of SPS:PPS
– State diagram was very complex
 Add “Cancel Request”
 Improve Status/Result Monitoring
– Getting PPS feed was awkward;
required configuration and forwarding

3. Interesting UPS Features
 Remote create
 Task Locking by performer
 Deletion Locking by watchers
 Subscription-based Monitoring
 “Gift Subscriptions”
 Push, Pull, and Watch Workflows
 Sub-contracting
 1-to-1 relationship between SPS and PPS
 4 SOP Classes operating on 1 IOD

4. UPS Architecture
 One object
– Each item on a worklist is a UPS Object
– UPS Object = Unified Procedure Step IOD
– Unified = contains details of both the
requested task & the performed task
 Four SOP Classes
– UPS Push SOP Class
– UPS Pull SOP Class
– UPS Watch SOP Class
– UPS Event SOP Class

5. UPS Object
UPS Object
Sched. Task Details
Progress
Perf. Task Details
Relationship
A UPS Object has its attributes
grouped into 4 Modules:
(this does not affect processing;
just for logical organization)

6. UPS Object Modules
UPS Object
Sched. Task Details
Progress
Perf. Task Details
Relationship Relationship Module
- Patient demographics
- Admission details
- Order details
- Requested Procedure
- Accession #
- Reason for Requested Procedure
- Requesting physician/department
- etc…

7. UPS Object Modules
UPS Object
Sched. Task Details
Progress
Perf. Task Details
Relationship
Scheduled Proc. Info. Module
- Priority
- Requested perform./completion time
- Requested resources/location
- Requested Procedure descrip./codes
- Requested Processing parameters
- List of Input data IDs
- Input Data Availability Flag
- etc…

8. UPS Object Modules
UPS Object
Sched. Task Details
Progress
Perf. Task Details
Relationship
Progress Module
- UPS State (Scheduled,
In-Progress, Completed, Canceled)
- Progress Status – Numerical
(e.g. % complete)
- Progress Status – Description
(e.g. Annealing phase complete)
- Contact information for performer
(e.g. phone #)
- etc…

9. UPS Object Modules
UPS Object
Sched. Task Details
Progress
Perf. Task Details
Relationship
Performed Proc. Info. Module
- Time Performed/completed
- Performing resources/location
- Performed Procedure descrip./codes
- Performed Processing parameters
- List of Output data IDs
- etc…

10. UPS State Diagram
SCHEDULED
IN PROGRESS
COMPLETED CANCELED
N-CREATE by an SCU
(or SCP internal logic)
N-ACTION by an SCU with the lock key
(or SCP internal logic)
N-ACTION by an SCU
(or SCP internal logic)

11. UPS
UPS Pull Workflow
3D Workstation
Worklist
Manager
(SCP)
Performer
(SCU)
Watcher
(SCU)
Requester
(SCU)
Query
Get UPS Contents
UPS State “In-Progress”
UPS State “Complete”
Set UPS Contents
Dashboard
System

12. UPS SOP Classes
UPS Object
Sched. Task Details
Progress
Perf. Task Details
Relationship
Each UPS Object is managed by a
single SCP.
4 SOP Classes exist which can be
used to operate on a UPS object.
Each SOP Class supports a few
related operations.
SCU/SCP not required to implement
all the SOP Classes. Can implement
SOP Classes based on the operations
it needs.

13. UPS SOP Classes
UPS Object
Sched. Task Details
Progress
Perf. Task Details
Relationship
UPS Push SOP Class
allows SCU systems to:
* create (push) a new worklist item
(i.e. instance) on a worklist
* request cancellation of a worklist
item

14. UPS SOP Classes
UPS Object
Sched. Task Details
Progress
Perf. Task Details
Relationship
UPS Pull SOP Class
allows SCU systems to:
* query a worklist for matching items
* take ownership/control (pull) of a
worklist item
* modify progress/status/result details
for the worklist item
* finalize a controlled worklist item as
Completed or Canceled.

15. UPS SOP Classes
UPS Object
Sched. Task Details
Progress
Perf. Task Details
Relationship
UPS Watch SOP Class
allows SCU systems to:
* query a worklist for items of interest
* subscribe/unsubscribe for change
events for one worklist item
* subscribe/unsubscribe for change
events for all worklist items
* get details for a worklist item
* request cancellation of a worklist
item

16. UPS SOP Classes
UPS Object
Sched. Task Details
Progress
Perf. Task Details
Relationship
UPS Event SOP Class
allows SCU systems to:
* receive change events for worklist
items

17. UPS Task Locking
For a UPS in SCHEDULED State:
 (SCU does N-ACTION to IN-PROGRESS)
 SCP generates a lock ID
 (SCP returns lock ID to performing SCU)
For a UPS in IN-PROGRESS State:
 N-SET without lock ID is rejected by SCP
 N-ACTION to change state “ “
 Of course, lock ID could be distributed,
but be careful

18. Pull Workflow
R I S
3D Workstation
Give me a list of tasks that need to be done
(C-FIND)
UPS
UPS
UPS
UPS
SCP SCU
I will do that one
(N-ACTION Set to IN-PROGRESS)
I am finished
(N-ACTION Set to COMPLETE)
Record these details in the UPS
(N-SET attribute values)

19. Pull Workflow – 3D Workstation
3D
Workstation
3D
Workstation
Acquisition
Modality
RIS 3D
Worklist Manager
3D
Workstation
Store Images
PACS
Add UPS Task (N-CREATE)
MPPS Complete
Create UPS for Task X
Add RIS to Task X
Subscriber List (based on
prior Global Subscription)
Query Worklist (C-FIND)
Confirm Availability
of Task X inputs
Query Input Image Instances
Select UPS for Task X
Claim Task X
(N-ACTION IN-PROGRESS)
Report Task X In-Progress (N-EVENT)
Retrieve Input Image Instances
Return Transaction-UID
Generate 3D Views
requested in Task X
Store 3D Views
Complete Task X
(N-ACTION COMPLETE [T-UID])
Report Task X Complete (N-EVENT)
Record Task Details
(N-SET [T-UID] )
Retrieve Final State Details (N-GET)
Retrieve full details for Task X
(N-GET)

20. Comparison to Modality Worklist
 MWL is like UPS Pull-mode, except
– UPS combines SPS and MPPS in a single object
– UPS has extra features
 UPS will not generally replace MWL
– MWL does it’s (limited) job reasonably well
– MWL has a large install base
 UPS might supplement MWL for specific
applications that need it’s features
– e.g. Push Workflow for X-Ray clinics

21. Push Workflow
R I S
3D Workstation
Please perform this task
(N-CREATE with these attribute values) UPS
SCU SCP
I have started to do that task
(N-EVENT it is IN-PROGRESS)
I am finished
(N-EVENT it is COMPLETE)
I have updated details in the UPS
(N-EVENT)
Notify me about progress for that task
(N-ACTION Subscribe)
Give me the result details of the task
(N-GET these attribute values)

22. Push Workflow – X-Ray Clinic
X-Ray
(Room #3)
X-Ray
(Room #2)
PACS
X-Ray
(Room #1)
RIS
Add UPS Task (N-CREATE)
Create UPS for Task X
Update Task X UPS Status to
IN-PROGRESS
Report Task X In-Progress (N-EVENT)
Report Task X Complete (N-EVENT)
Update Task X Details
Retrieve Final State Details (N-GET)
Subscribe globally for events
(N-ACTION SUBSCRIBE [Well-Known Instance])
. . .
Update Task X UPS Status to
COMPLETE
Store Images
Display Progress
“Exam Started”
Update Task X UPS Progress to
”All Views Taken”
Report Task X Progress (N-EVENT)
RIS assigns Mr. X
to Room 1
Delete Task X
Display Progress
“Exam Complete”
Patient (Mr. X) arrives at Reception
Patient (Mr. X) arrives at X-Ray Room 1 Tech confirms identify of Mr. X
and begins procedure
Display Progress
“All Views Taken”
UnSubscribe for Task X
(N-ACTION SUBSCRIBE [Task X])

23. Watch Workflow
 No central controller
– Workstation watches flow of N-EVENTs:
“System A did X”, “System B did Y”
– Workstation decides “Hmmm, I think I will do this”
– Workstation internally creates a UPS
– Interested Subscribers are notified of Workstation
activity via N-EVENT; N-GET details as needed
 Examples:
– CAD workstation sees N-EVENT that Mammo
Acq. is complete; decides to do CAD processing
– Reporting station sees N-EVENT that CAD is
complete; decides to queue reading worklist for
that study

24. Example Implementation Groupings

25. Deletion Locks & Reliable Watchers
 Reliable Watcher (SCU)
– Problem: SCP might delete a completed UPS before SCU gets
needed details
– (e.g. due to Network latency or outage)
– Missing a UPS could prevent Watcher from:
 monitoring completion
 extracting details
 creating subsequent UPS Instances,
 referencing UPS 1 outputs as UPS 2 inputs
 Mechanism
– SCU Sets a Deletion Lock flag during subscription
– SCP can’t delete UPS with outstanding Deletion Locks
– SCU removes Deletion Lock after retrieving final state of UPS
– SCP free to delete UPS after all deletion locks removed
– SCP documents how it handles orphans

26. Requesting Cancel
User
Terminal
Treatment
Delivery
System
Treatment
Management
System
Find UPS Task of Interest (C-FIND)
Update Task X Details (N-SET w TUID)
…
Operator agrees and
cancels Task X
User decides to cancel Task X
Request Task X Cancel
(N-ACTION REQUEST CANCEL) Report Task X Cancel Requested (N-EVENT)
Report Task X Canceled (N-EVENT)
Start Task X (N-ACTION IN PROGRESS)
Return Transaction UID (TUID)
User selects Task X
Start listening (N-ACTION SUBSCRIBE [Task X])
Return Current Task X Status (N-EVENT)
Copy Contact URI from Request into N-EVENT
Display Cancel Request
for Task X and Contact
URI to Operator
Operator pauses task &
uses Contact URI to call
user & discuss cancel
Cancel Task X (N-ACTION CANCELED w TUID)

27. Current DICOM Status
 Sup 96 (UPS)
– Officially published as Frozen for Trial Use
 Sup 74 (Radiotherapy Treatment Delivery Workflow)
– Officially published as Frozen for Trial Use
– Defines Treatment Delivery Objects
– Documents use of UPS for RT
– UPS references instances of RT Beams Delivery Instruction
– Treatment Delivery System (SCU) pulls work from the Treatment
Management System (SCP)
– Z.3.1.2 gives detailed example of UPS usage, specifying both the
task and input objects
 Sup 124 (Softcopy Display Mgt.)
– Under development
– Defines Display management/callibration Tasks & Results
– Uses UPS to push Display Calibration jobs (with Task description)
& convey Results

28. Current IHE Status
 IHE Radiation Oncology
– Planning to test Sup 74 workflow using UPS
 IHE Mammography
– expressed interest in UPS features; (not committed yet)
– UPS could help handle complex cases such as:
 Multi-pass Acquisition
 Callbacks
 CAD
 Reading Worklists
 IHE Radiology
– no plan to replace Modality Worklist for acquisition workflow
– will consider UPS when re-visiting Reporting Workflow
and Post-processing Workflow
– may profile Sup 124 when it’s ready

29. Questions?
www.dclunie.com
> DICOM Status
> Sup 96