Research And Implemetation Of A Number Of Key Issues In PACS System

PACS is the product of the rapid development of modern healthcareinformation technology. Originally, it was designed for the radiologist tofacilitate the management of medical images. Now, it has become anindispensable tool in hospital information management. With the rapiddevelopment of Web technology, PACS has also developed in the directionto the Web Application. In this process, a symbolic significance event is thebirth of WADO technology. WADO is a technology which is used foraccessing the DICOM object on the Web. Since the emergency of thistechnology, the web-based PACS soon becomes a reality. Although PACShas been widely used, and Web-based PACS is also being popularized in thehospital, but the development of PACS still faces a lot of technologicalbottlenecks and there are still many issues worthy of in-depth study in PACS.For example, the possible issues include content-based image retrievalproblem, the three dimension display problem of medical images and theoptimization problem of the medical image database, and so on. Based onrelated work at home and abroad, this paper researches on these three issues separately.About to content-based image retrieval, this paper focuses on the threekinds of algorithms, namely, mutual information algorithm, GLCMalgorithm and edge direction histogram algorithm. These three algorithmsrepresent three types of CBIR algorithm, which are based on grayscalehistogram, texture features and shape features respectively. Based on thesethree kinds of algorithms, this paper proposes related improvements basedboth on recall ratio and precision ratio. As to mutual information method, itsasymmetry has been corrected. As to GLCM method, this paper proposes theconcept of generalized grayscale pixel rotation element, which can be usedto decrease the algorithm's sensitivity to the scale and direction of the image.As to the edge direction histogram method, this paper proposes to retrieveimages using this method and the invariant moment algorithm withgeometric invariance simultaneously. On that basis, the original algorithm issensitivity to image rotation.As to three dimension display of images, this paper studies the algorithmof image volume rendering and its acceleration mechanism. Two methods areapplied in mini-PACS for volume rendering. They are ray cast method andshear deformation method. The ray casting method is relatively slower thanthe other one because it is a direct volume rendering method. As to the raycasting method, the level-test method can be applied to it to avoid the calculation for the empty voxel.As to the optimization for the medical image database, four-storymedical image information model which is based on the database can beapplied to it. The optimization can be executed by creating index on the fieldwhich is retrieved frequently and adjusting the structure of the indexdynamically.These are the main contents of this paper, on that basis, the web-basedmini-PACS system can be achieved and improved. The system consists ofimage retrieval module, image display module, image transmission moduleand image archiving module. So it has the core function of the commonPACS. Compared to C/S structure system, web-based PACS has manyincomparable advantages, such as low cost, strong scalability, ease of useand so on. These advantages will allow web-based PACS to be the majordevelopment direction in PACS architecture field.