Unified Post-Processing Workflow with Application Hosting - Brief Proposal
1. Proposed Workitem: Unified Post-Processing Workflow with Application Hosting
- Proposal Editor: Lawrence Tarbox, Ph.D.
- Editor: TBD (I could assist, but I’m not formally part of the TC, and have no travel funds)
- Domain: Radiology
2. The Problem
The existing post-processing workflow profile needs to be upgraded to take advantage of new developments in the DICOM Standard, specifically the Unified Worklist and Procedure Step, and Application Hosting.
The Unified Worklist and Procedure Step (UPS) is intended to be simpler to implement, and addresses certain integration problems encountered with the older General Purpose Procedure Step (GPPS) currently specified by the Post-Processing Workflow Profile. In addition, the UPS opens up options unavailable in the older GPPS.
Coupling UPS with DICOM Application Hosting in a revamped post-processing workflow opens up a world of possibilities for the potential automation of post-processing options, including chaining of sequential operations.
3. Key Use Case
After data has been acquired and archived, it often is desirable to automatically trigger analysis or post-processing of that data. This analysis or post-processing might be performed automatically (e.g. create CAD reports, agent or function specific post-processing), or may be semi-automated or manual analysis of that data done by a human operator (e.g. registration of datasets, fusion of datasets, segmentation, image enhancements). The output from this analysis or post-processing would then be made available to the physician who could then refer to the output in making a final report.
The use cases found in Annex XX of Part 17 of the 2011 DICOM Standard describes several analysis categories that could benefit from this proposed automation of post processing workflow.
While this profile is similar to the existing IHE Post Processing Workflow (hence the use cases there may still be applicable), there are some key differences. First, we propose replacing the General Purpose Procedure Step used in the current IHE profile with the new Unified Worklist and Procedure Step mechanisms. Second, we propose adding support for Application Hosting, so that the worklist items also identify the application (or application category) that is needed to accomplish the task identified by the worklist item.
4. Standards and Systems
The proposal would include a workflow manager, an image and/or report manager, and a post-processing server or workstation.
The proposal utilizes the following aspects of the DICOM Standard:
- Unified Worklist and Procedure Step (Incorporated into the Standard in 2011, originally published as Supplement 96)
- Application Hosting (Incorporated into the Standard in 2011, originally published as Supplement 118)
5. Discussion
While DICOM defines the basic mechanisms for both Unified Worklists, Procedure Steps, and Application Hosting, DICOM does not specify how these mechanisms can be orchestrated to accomplish tasks within a departmental workflow. IHE would seem to be the preferred venue for profiling how these mechanisms work in concert to accomplish procedure steps needed to fulfill an imaging service request or order. While the details have yet to be worked out (hence this proposal), the sequence of events might be as follows:
1. A workflow manager is informed that data has been acquired (e.g. by completion of a Modality Performed Procedure Step).
2. The workflow manager determines that additional post-processing steps are desired prior to completing the final report
3. The workflow manager creates new worklist items (procedure steps) to accomplish the desired post-processing, and queues them up for appropriate post-processing servers or workstations.
4. The post-processing servers or workstations pick up worklist items queue for them, and launch appropriate Hosted Applications to accomplish the tasks. The pickup could either be done automatically, for Hosted Applications that do not require human interventions, or could be done interactively under control of a human operator.
5. When the Hosted Application has completed its analysis or post-processing, and sent the results back to the Hosting System (i.e., the post-processing server or workstation), the server or workstation stores the results to an image and/or report manager, and closes out the worklist item.
6. Upon receiving notification of a closed worklist item, the workflow manager may create and queue additional worklist items, building upon the previous output.