Design of multiparty consultation capability for a PACS

The PACS developed previously at the Delft University did not allow for real time interaction between specialists at different viewing stations. Recently, we enhanced our PACS with a Consultation Capability to provide a user with the ability to consult colleagues at other viewing stations. This consultation capability enables viewing the same image(s) simultaneously at different workstations and provides overlay information of pointers and rectangles, generated at one site, to become visible at the other site(s). In our earlier PACS, viewing of images is initiated by starting the Xclient application at one of the viewing stations. This procedure has been enhanced to enable a user to select two modes of operation namely either single- or multi-user session mode. In the new multi-user mode, all viewing stations involved in the same session, communicate with each other via a central control application (called consultation server), which is part of the enhanced supervisor. In the multi-user mode, only one user is allowed to select images, which will be displayed at all viewing stations involved in the session. The new viewing program sends it mouse information and framing information to the consultation server, which distributes this information to the other connected viewers. It is desired to remain DICOM compatible, however, ACR/NEMA has not (yet) handled the standardization of commands concerned with real-time consultation. Two different DICOM SOP (Service Object Pair) classes have been created. The first class is used to setup consultation, whereas the second class is used to exchange consultation data.