Picture archiving and communication system (PACS)

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Picture archiving and communication system (PACS) are a collective group of workstations, servers, and archives, all tied to one or more imaging modalities (CT, MRI, ultrasound machines, etc.) to act as a database and processor of imaging data.


The data involved is not solely contained within the image, there is plenty of metadata and patient information to accompany this digital film, some of which is handled by other systems. Like any networked computer system, a PACS can range from small and simple in the form of several machines, up to enterprise-level complexities, serving up large quantities of images and data from various modalities to a range of disparate end-user situations. More specifically, a typical PACS would likely involve a RAID (redundant array of independent disks) storage archive, an imaging device such as an ultrasound machine, workstations with high-resolution monitors, software for retrieval and display of the images, and an intranet (or internet) network connection to tie them all together.1 Ideally a PACS would also provide multi-modal image acquisition, report generation and dictation tools, although these features are not defining.

The PACS acronym was established in 1982, at the First International Conference on Picture Archiving and Communication Systems.1 Yet the basic idea of moving medical imagery over telephone lines dates back to 1929,2 and had been described several years prior to the conference.3 The earliest PACS systems could be as simple as a film scanner and dial-up connection between two machines, and while second-generation systems in the latter-half of the 1980s placed more emphasis on the storage, retrieval and display features, were troublesome,1 and still designed with a film-producing workflow in mind. They showed potential, but needed an entrenched communications standard such as DICOM.

Digital Imaging and Communications in Medicine (DICOM) is a well-accepted standard for image metadata. As a standard, it provides guidelines for interfacing between an image modality and an image storage or retrieval system.

Radiology information systems (RIS) share close ties with PACS in an organization's workflow, but RIS as an idea more closely resemble Health Information Systems (HIS), and can even be considered a subset of HIS, or type of HIS specific to the radiology department. RIS provide information such as patient scheduling data, document management, billing and other adjunct information. Together, RIS and PACS are the two founding elements needed for a completely digital radiology department. When remote access is needed, it is likely the RIS would be involved with the PACS. For more information about RIS and PACS integration into other CIS systems, click here.

In just the 15 years that they've been available,4 a stereotypical PACS installation has evolved from a small-scale operation somewhat confined to the radiology department. Current PACS approaches tend toward large-scale, Health Level Seven (HL-7) compliant systems deeply embedded into the workflow of the whole hospital.


  1. Sending dental x-rays by telegraph Anonymous, Dent Radiog Photog 2 (1929) (1), pp. 1–2.
  2. Lemke, HU (1979) A Network of Medical Work Stations for Integrated Word and Picture Communication in Clinical Medicine, Technical Report., Technical University, Berlin
  3. Siegel E, Reiner B. Work Flow Redesign : The Key to Success When Using PACS [Internet]. AJR. American journal of roentgenology. 2002 ;178(3):563-6. Available from: http://www.ajronline.org/cgi/content/abstract/178/3/563