The concept of PACS was introduced in the early 1980s. The idea of establishing PACS was mainly caused by two main factors: one is the creation of digital imaging equipment, such as CT equipment, which enables medical images to be obtained directly from the examination equipment; the other is the development of computer technology, which enables the storage, communication and display of high-capacity digital information. In the early 80's, Europe, the United States and other developed countries based on the mainframe computer hospital management information system has basically completed the research stage and turned to the implementation of the research in the mid-80's on the gradual shift to the system for medical services, such as clinical information systems, PACS and other aspects. In Europe, Japan and the United States and other successive establishment of research PACS laboratories and experimental systems. With the development of technology, to the early 90's has been established a number of practical PACS.
In the mid to late 80's the medical imaging system studied mainly used special equipment, the whole system is very expensive. By the mid-1990s, the creation of computer graphics workstations and the development of network communication technology led to a decrease in the overall price of PACS. Into the late 1990s, the rapid improvement of microcomputer performance and the rapid development of the network, so that PACS can be established at a level that can be accepted by a larger number of hospitals.
Second, the functional configuration of PACS
PACS (hospital image storage and communication system) in the hospital imaging department rapidly spread, as computers and the Internet increasingly deep impact on our daily lives. PACS is also changing the way the imaging department operation, a high-efficiency, film-free imaging system is quietly emerging. The main roles of PACS in these changes are:
1) PACS connectivity
In order to be able to network imaging equipment, a prerequisite is the digitization of the images themselves. At present, the new production of CT, MR, digital X-ray machine, nuclear medicine equipment have DICOM image output interface, can be directly connected with the PACS. For those who do not have a DICOM interface equipment, access to PACS is more complex, to use specialized equipment to start the image converted to DICOM standards and then access to PACS. For the old model of CT, MR, generally need to increase the special upgrade module to achieve, using this method of image quality is guaranteed, the integrity of the data is also better, but the price is usually higher. For non-digital X-ray machines, the usual way is to use a digital sensor screen (CR) or through the film directly through the scanner into a digital image. Another commonly used conversion method is video capture (Screen Capture), both on the video signal equipment (such as ultrasound, nuclear medicine equipment), the video signal can be converted to DICOM images.
2) PACS image storage and management
Medical image data volume is usually very large, a conventional CT scan for the 10MB order of magnitude, while the chest X-ray machine can be up to 20MB, cardiovascular angiography images can be up to 80MB or more, 128 rows of three-dimensional reconstruction of the CT image can be up to 1GB. storage and management of the image for the PACS system, an important feature, the cost of realizing this function accounted for the cost of the system. Storage and management of images is an important function of a PACS system, and the cost of realizing this function accounts for 20%-60% of the total cost of the system. Small PACS workstations can use a 100GB server to store images and a CD burner to save them permanently. Large and medium-sized PACS use different types of storage devices to achieve different requirements, usually in terabytes as the storage unit, tertiary hospitals, storage capacity can be as high as dozens of terabytes.
3) Image recall and post-processing functions
All PACS image data is ultimately intended to be recalled and processed. Digitized images can be displayed directly on the computer's monitor. The monitor's performance in terms of resolution, contrast, brightness, noise and distortion directly affects the quality of the digitized image, thus influencing the final diagnostic result. Due to the large amount of medical image information, in order to facilitate storage and transmission, improve the efficiency of PACS, it is necessary to image compression processing, especially for high-resolution color images is more necessary to compress.