PACS viewer interoperability for teleconsultation based on DICOM

Real-time teleconsultation in radiology enables physicians to perform same-time consultation between remote peers, based on medical images. Since digital medical images are commonly viewed on PACS workstations, it is possible to use one of several methods for remote sharing of the computer screen. For instance, software products such as Microsoft NetMeeting, or IBM SameTime, can be used. However, the amount of image data transmitted can be very high, since even minute changes in an image window/level requires re-transmitting the entire image again and again. This is too inefficient. Looking for better methods, when restricting the problem to the use of same hardware and software of the same vendor, it is easier to develop a solution that employs a proprietary specialized protocol to coordinate the visualization process. Such is a solution that we developed, and which demonstrated an excellent performance advantage by transmitting only the graphical events between the machines, rather than the image pixels. Our solution did not inter-operate with other viewers. It worked only on X11/Motif systems, and only between compatible versions of the same viewer application. Our purpose in this paper is to enable inter-operability between viewers of different platforms, and different vendors. We distinguish three parts: Session control, audiovisual (multimedia) data exchange, and medical image sharing. We intend to deal only with the third component, assuming the use of existing standards for the first two parts. After a session between two or more parties is established, and optional audiovisual data channels are set, the medical consultation is considered as the coordinated exchange of medical image contents. Some requirements for the contents exchange protocol: In the first stage, the parties negotiate the actual set of capabilities to be used during the consultation, using a formal description of these capabilities. The capabilities that one station lacks over the other (such as specific image processing algorithms) can be 'borrowed.' In the second stage, when interaction starts, it should assume that the graphical user interface of the stations might be different, as well as working procedures. During the consultation, data is exchanged based on DICOM for the data model of medical image folders, and the data format of image objects.