PACS
Image archiving and communication systems, which are used to transmit, store and distribute data are called PACS (“Picture Archiving and Communication System”). Developed in late 1980’s, this system serves independent subsystems which we call “module”. Thus, traditional film-oriented usage yield to data transmission at electronic platform.
As well as fast transmission of images to destination, PACS allows users to access to images from multiple-modalities easily. Since images are stored digitally on PACS system, the need for film usage has started to disappear as PACS provided a more affordable solution.
PACS systems, while being capable of being integrated to many hospital information systems, also has to have a structure that works with PACS infrastructure in a harmony. Providing the connection between these two layers is very important for our systems. PACS infrastructure is designed to be modular, extendible - as being able to gain new features - and affordable. Internationally accepted imaging and image storage format is called “DICOM” (“Digital Imaging and Communications In Medicine”).
PACS system consists of 4 components, the network that helps transmission of patient information, workstations where data is reviewed, modalities and archive (server) that is used to retrieve and store images. Since our solutions have to be compatible with various kinds of servers, workstations, devices and network, they are developed to meet miscellaneous kinds of needs and expectations.
PACS Architecture
Three basic kinds of PACS architecture are used as Independent Model, Client-server Model and Web-based Model:
Independent PACS Model
PACS server is consisted of modality (CT, MRI, DX etc.) and workstation components. Images retrieved from source are sent to PACS archive server and stored. Copies of the images on server are sent automatically to users’ workstations to be read and examined. Images are only sent to selected workstations. If a problem occurs during this operation and operation becomes incomplete, users can retrieve or query the image in archive, but since images are cached, they can only store a limited number of them. On the other hand, in case of a failure, since images have copies on server, risk of data loss gets reduced.
Client-Server Model
As independent PACS model, it is consisted of server, modality and workstations. At the center of this architecture, there is a PACS server that stores the images. Images stored on server are selected via a list that is retrieved from and presented to user and can be filtered. Since workstations have no memory for storage, images are deleted after they are read. Each workstation has a full permission to access to the archive server’s database. Since each workstation has the list of images already, data retrieval and query operations are not needed in this model. The only disadvantage of this model is to prevent workstations from accessing or reaching to data in case of a failure in central server.
Our RadiPACS solution, providing access and secure storage to DICOM images, is server-based and has the structure of Client-Server Modelled PACS architecture where workstations are able to keep the list of images.
Web-based Model
Being similar to Client-Server Model, client is a web application in this model. Therefore, we can say that client is limited to functions which are provided by web applications. Web-based model can be applied to every platform that provides web infrastructure.
Our RadiPACS Web Viewer solution that enables users to access to patients’ medical images via web interface and make various operations on them is structured as Web-based Model architecture where clients require web infrastructure.
