Tuesday, September 29, 2009

PACS


PACS

(picture archiving communication system)

In medical imaging, picture archiving and communication systems (PACS) are computers, commonly servers, dedicated to the storage, retrieval, distribution and presentation of images. The medical images are stored in an independent format. The most common format for image storage is DICOM (Digital Imaging and Communications in Medicine). Electronic images and reports are transmitted digitally via PACS; this eliminates the need to manually file, retrieve or transport film jackets. A PACS consists of four major components: the imaging modalities such as CT and MRI, a secured network for the transmission of patient information, workstations for interpreting and reviewing images, and long and short term archives for the storage and retrieval of images and reports. Combined with available and emerging Web technology, PACS has the ability to deliver timely and efficient access to images, interpretations and related data. PACS breaks down the physical and time barriers associated with traditional film-based image retrieval, distribution and display.


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)


Uses:

PACS has two main uses:
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.
Remote access: It expands on the possibilities of conventional systems by providing capabilities of off-site viewing and reporting (distance education, telediagnosis). It enables practitioners in different physical locations to access the same information simultaneously for teleradiology.
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.
One difficult area in PACS is interpreting the DICOM image format. DICOM does not fully specify the metadata tags stored with images to annotate and describe them, so vendors of medical imaging equipment have latitude to create DICOM-compliant files that differ in the meaning and representation of this metadata. A feature common to most PACS is to read the metadata from all the images into a central database, allowing the PACS user to retrieve all images with a common feature no matter the originating instrument. The differences between vendors' DICOM implementations make this a difficult task.

A PACS can store volume data from exams and reconstruct 3D images
Some medical modality vendors have defined private DICOM tags to introduce added features. Tags like this are permitted according to DICOM protocol and will not impact on the images in most cases, but will not operate when the image is viewed on a different platform.


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