Image storage is a bit of a conundrum; if cost weren't a factor, healthcare organizations could store all of their digital medical images on the highest-performing, most reliable storage media on the market. But since cost is always a factor, medical imaging archives must incorporate ingenuity in their design, including lower cost media while still meeting end-user requirements for accessibility, reliability, availability and performance.
Image archiving is challenging; albeit not impossible. Some 20 percent of U.S. healthcare facilities have deployed PACS, according to industry estimates, and all are using a combination of storage hardware and storage software to automate management. But what constitutes a robust, reliable, scalable and affordable PACS storage plan? Strategizing can be arduous as technological improvements change options and healthcare organizations - large, medium and small - have different digital imaging, PACS and archiving needs.
But there is some common ground. PACS storage consists of short- and long-term caches that securely and reliably disseminate medical imaging data when needed to physicians and clinicians throughout the enterprise and remotely. The media chosen for each reflects the speed with which the image data needs to be accessed.
In the past, a healthcare facility may have had a couple years of long-term storage on slower-access, lower-costing media; putting the online archive on fast spinning disk. A tape unit may have backed up the long-term archive. Once the study was validated, the data would be moved from the online archive to the long term archive over to the disaster recovery. However, the declining cost of storage media, such as spinning disk, is changing the paradigm.
Every PACS team must evaluate the amount of data stored, retrieval times, costs and integration with various applications. State and federal laws will influence how long electronic patient images must be stored. Also, users should adopt a "buy as you need it" approach to storage media to mitigate the difficulty of data migration and avoid data obsolescence.
Trends in long-term storage are impacting PACS archiving. Exponentially increasing storage requirements due to the introduction of new imaging technology and other 'ology' image storage beyond radiology is one. The healthcare community is starting to look at spinning disk as a viable option for both short- and long-term needs as costs decline and capacities increase. Medical imaging data are getting replicated to off-site facilities for disaster recovery and business continuity requirements. Architectures are expanding to enterprise archives, rather than individual silos of storage managed separately by departments.
Policy-based data management, which permits medical imaging studies to be intelligently filed during its lifecycle, is another influential long-term storage trend. Phoenix-based Banner Health, which manages 21 facilities across seven states -Alaska, Arizona, California, Colorado, Nebraska, Nevada and Wyoming - uses this technology to cost effectively meet retrieval requirements and economically optimize storage costs.
Banner's greatest concentration of facilities and procedure volumes are in Arizona. In total, they perform more than 800,000 radiology and cardiology exams annually. Transitioning to digital imaging, Banner's Arizona facilities needed a storage infrastructure that could easily scale to 1.2 petabytes - its projected imaging volume by 2009.
Tim McFarlan, director of technology management, says the enterprise-wide project has high availability, multi-facility requirements. Retrieval of mission-critical data must be instantaneous as hundreds of clinicians access the archive daily. Scalability is crucial since huge amounts of electronic data will be produced annually. Security and data integrity must be maintained so that state retention mandates and federal government regulations, such as Health Insurance Portability and Accountability Act (HIPAA) requirements, are met.
McFarlan says that the storage must interface with multiple PACS. "We quickly realized that if we were to develop a common archive solution for Banner's Arizona-based facilities, we needed to find an archive that would support both the archival retrieval process of radiology PACS and also other DICOM-based image management systems used in other imaging-related departments, such as cardiology," says McFarlan.
Banner selected a multi-tiered storage hierarchy