PACS (Picture Archiving and Communication System), along with the evolution of DICOM (Digital Imaging and Communications in Medicine) standards, has grown to truly provide a filmless environment in many hospitals and clinical facilities all over the world. The integration of DICOM between digital imaging modalities, RIS (Radiology Information System), HIS (Hospital Information System), and EPR (Electronic Patient Records) provides the prerequisites necessary for systems to achieve invaluable communication possibilities among almost all of today’s manufacturers and for the platform of this filmless world of PACS to exist. Efficient use of PACS software, however, is not only crucial to sustain the daily workflow of a hospital but also essential for a busy one.

With the user in mind, which should always be the beginning point in any information system development, PACS must do, at the very least, two things – provide access to all available pictorial and alphanumeric patient data, and, secondly, to retrieve and display this data in an acceptable response time.

For this to happen, RIS and HIS must certainly be linked to the PACS, and will generally be the primary source of alphanumeric data, but the response time is directly related to an effective PACS management of the image database. This is accomplished by the use of a concept called prefetching, or more appropriately, intelligent prefetching.

Prefetching allows historical images to be “prefetched” from an archive, as is the case for a patient, let us say, who registered for a radiological exam, while the examination is being performed. A set of rules exists for prefetching limiting the retrieval of images to a configurable number of past exams, the same modality, and the same body part, relevant to the current clinical problem, so that a diagnostic comparison can be made without unnecessarily overburdening and slowing down the network and PACS equipment. To further optimize the use of PACS, prefetching can be executed during night time hours, where utilization of PACS is probably at lowest levels. Depending on where the images are stored, the time it takes to prefetch is markedly noticeable.

If images are stored locally, images appear on workstation monitors in less than 3 seconds and even faster once the image gets stored in RAM of that particular workstation, whereas, if stored in a long-term archive, images load in two to three minutes, or even five to ten minutes on a wide-area network.

Another concept is the utilization of worklists and folders. Depending on the workflow in a particular clinical setting, worklists and folders will differ depending on various needs and are adapted and made site specific. Worklists refer to work that has to be done, and folders are groupings of exams that need to be accessed in different ways (e.g. by body part or by referring clinician) according to the clinical setting.

As way of review, in PACS I Going Filmless we discussed the decision for a clinical practice to deploy a PACS, in PACS II Pre-PACS Prep we discussed workflow prep and software integration, and in PACS III Assessment of Purpose we talked about PACS software, workstations and cost savings. Finally, MedicExchange reported on the growth in the PACS market, expected to reach $4.8 Billion by 2015. Thank you for staying tuned to MedicExchange to learn from our introductory series on PACS. Certainly there is more to learn about PACS so please join our Friends social network to discuss PACS and other areas of radiology interest with your peers. MedicExchange.com wishes to welcome company participation in our PACS product review and radiology experts and customers to join in reviewing PACS products.

References:

• Strickland N H: 1997 Implications of a filmless hospital for a radiological service. In: Proceedings of the 5th International Conference on Image Management and Communication (IMAC) ′97. Seoul, Korea. Proceedings of the PakMedTek Symposium.
• Okkalides D: Assessment of commercial compression algorithms, of the lossy DCT and lossless types, applied to diagnostic digital image files. Comput Med Imaging Graph 1998; 22:25-30.
• Toney MO, Dominguez R, Dao HN, Simmons G: The effect of lossy discrete cosine transform compression on subtle bone fractures. J Digit Imaging 1997; 10:169-173.
• van Ooijen PM, Roosjen R, de Blecourt MJ, van Dam R, Broekema A, Oudkerk M: Evaluation of the use of CD-ROM upload into the PACS or institutional web server. J Digit Imaging, 2006; 19(suppl 1):72-77.
• Crespi A, Bonsignore F, Paruccini N, Macchi I: Grayscale calibration and quality assurance of diagnostic monitors in a PACS system. Radiol Med (Torino), 2006; 111:863-875.

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