The Research On Key Technologies Of Distributed PACS

With the development of information technology, the traditional PACS (Picture Archiving and Communication Systems) with two-tier architecture cannot accord with the development trend that PACS is more large-scale, more complex, and more distributed than before in future. Moreover, it would seriously restrict the performance and popularization of PACS. Therefore, it's urgent to develop a new Distributed PACS (DPACS) architecture.Regarding DPACS as research object, this dissertation gives emphasis to key technologies such as DPACS architecture, PACS-oriented extensible ORB communication framework, DICOM interconnection & interoperability methods, and several PACS application service technologies. The dissertation'goal is to develop a portable, extensible, configurable and open DPACS system with high-performance. In detail, main contributions of the dissertation are as follows:(1) This dissertation proposes a CORBA-based DPACS in three-tier architecture. Based on thoroughly analyzing of traditional PACS architecture, importing DOC environment of CORBA and researching combination of CORBA and DICOM standard, this dissertation proposes CORBA-based DPACS in three-tier architecture. Moreover, this dissertation proposes DPACS middle-tier configuration consisting of design pattern tier, CORBA service tier, DICOM interconnection & interoperability service tier and PACS application service tier.(2) This dissertation proposes the concept of Inter-DPACS in which lots of DPACS collaborate with each other. For satisfying the needs of interconnection & interoperability in DPACS that locate at different regions and countries, this dissertation develops the concept of Inter-DPACS that are divided into three classes including Center/ Regional/ Local DPACS, which collaborate with each other and organize the whole Inter-DPACS together.(3) This dissertation proposes PACS-oriented extensible ORB communication framework based on design patterns. Based on standard DOC middleware of CORBA, the DPACS communication framework applies design patterns, which include Facade Wrapper, Reactor, Acceptor/Connector, Active Object and Service Configurator pattern, to extend ORB core's performance. As a result, it not only improves the portability and extensibility of DPACS, but also satisfies the QoS needs such as large throughput and low latency of DPACS.(4) This dissertation proposes the methods of DICOM interconnection & interoperability in distributed environment. Firstly, this dissertation proposes DICOM network communication model that consists of TCP SOCKET layer, DICOM upper protocol layer, DIMSE message exchange layer and SCU/SCP layer; Secondly, this dissertation proposes a sets of interfaces and mechanism for DICOM medical image access in distributed environment; At last, this dissertation proposes the control & management mechanism of DICOM workflow in Inter-DPACS, and develops Case-Manager service component and a series of intelligent control & management algorithm.(5) This dissertation designs and implements several PACS application service technologies. Firstly, aiming at DICOM medical image, this dissertation proposes the window width & center setting methods based on image content; Secondly, this dissertation researches JPEG-LS compression algorithm and implements it, and then gives algorithm implementation flow and test results; Lastly, through integrating the workflow of HIS/RIS and PACS, this dissertation researches the mapping methods of data elements and protocol event in HL7 and DICOM standard, and then designs and implements HL7 data exchange service for data fusion between PACS and HIS/RIS.(5) This dissertation designs and implements DPACS prototype, which gives a sound support to the above framework and methods of DPACS research.In a word, this dissertation researches several key technologies of DPACS, and validates the research thoughts by designing and implementing prototype system. The research is benefit for development of PACS now and in future. The development of key technologies of DPACS will not only improve the qualities of medical image application and management, but also accelerate the construction of IHE (Integrating the Hospital Enterprise) and the integration of PACS in regions, countries, and even whole world.