Picture archiving and communication system

Picture archiving and communication system (PACS)

A picture archiving and communication system (PACS) is a medical imaging technology which provides economical storage of, and convenient access to, images from multiple modalities (source machine types). Electronic images and reports are transmitted digitally via PACS; this eliminates the need to manually file, retrieve, or transport film jackets. The universal format for PACS image storage and transfer is DICOM (Digital Imaging and Communications in Medicine).

Types of images

Most PACSs handle images from various medical imaging instruments, including ultrasound (US),magnetic resonance (MR), positron emission tomography (PET), computed tomography (CT), endoscopy (ENDO), mammograms (MG),Digital radiography (DR), computed radiography (CR) ophthalmology, etc. Additional types of image formats are always being added. Clinical areas beyond radiology; cardiology, oncology, gastroenterology and even the laboratory are creating medical images that can be incorporated into PACS. (see DICOM Application areas).

Uses

PACS is offered by virtually all the major medical imaging equipment manufacturers, medical IT companies and many independent software companies. Basic PACS software can be found free on the Internet.

Hard copy replacement: PACS replaces hard-copy based means of managing medical images, such as film archives. With the decreasing price of digital storage, PACSs provide a growing cost and space advantage over film archives in addition to the instant access to prior images at the same institution. Digital copies are referred to as Soft-copy.

• Radiology Workflow Management: PACS is used by radiology personnel to manage the workflow of patient exams.

PACS is offered by virtually all the major medical imaging equipment manufacturers, medical IT companies and many independent software companies. Basic PACS software can be found free on the Internet.

Architecture

Querying & Image Retrieval

The communication with the PACS server is done through dicom objects that are similar to dicom images, but with different tags. A query typically looks as follows:

• The client establishes the network connection to the PACS server.
• The client prepares a query object which is an empty dicom dataset object.
• The client fills in the query object with the keys that should be matched. E.g. to query for a patient ID, the patient ID tag is filled with the patient's ID.
• The query object is sent to the server.
• The server sends back to the client a list of response dicom objects.
• The client extracts the tags that are of interest from the response dicom objects.

Image archival and backup

Digital medical images are typically stored locally on a PACS for retrieval. It is important (and required in the USA by the Security Rule's Administrative Safeguards section of HIPAA) that facilities have a means of recovering images in the event of an error or disaster. While each facility is different, the goal in image back-up is to make it automatic and as easy to administer as possible. The hope is that the copies won't ever be needed, but, as with other disaster recovery and business continuity planning, they need to be available if needed.

Integration

A chest image displayed via a PACS

A full PACS should provide a single point of access for images and their associated data. That is, it should support all digital modalities, in all departments, throughout the enterprise.

However, until PACS penetration is complete, individual islands of digital imaging not yet connected to a central PACS may exist. These may take the form of a localized, modality-specific network of modalities, workstations and storage (a so-called "mini-PACS"), or may consist of a small cluster of modalities directly connected to reading workstations without long term storage or management. Such systems are also often not connected to the departmental information system. Historically, Ultrasound, Nuclear Medicine and Cardiology Cath Labs are often departments that adopt such an approach.

Courtesy: en.wikipedis.org