Whenever a PACS is replaced by a successor system, plans must be made for access to historical data in the existing legacy system. The choices are to either keep the legacy archive running including an interface to new system, or migrate the data to the new system. The size and complexity of the data transfer task is such that data migration is a project element that must be explicitly planned and budgeted for.
Why Not Keep the Old Archive?
In most cases, it is technically feasible to simply keep the old system and query it for images when needed. However, a number of factors speak against this option:
- Technical – Aside from practical configuration management for a two-vendor two-archive system, the split in archive between the “old” and “new” must usually be maintained permanently in the institution’s workflow and staff training.
- Administrative – Retaining the legacy system also retains one more vendor to deal with, one more set of maintenance procedures to maintain, one more staffing consideration, and several more headaches that administrators would just as well avoid.
Because of plummeting costs of disk storage in recent years, retaining the legacy system generally entails costs that generally exceed the expense of additional storage on the new system.
- Legacy System Support Costs – The legacy PACS must be either maintained through annual support agreements with the legacy vendor, or by repairs performed as needed on a time-and-materials basis. Both these options are costly, and the latter should be considered only if the healthcare provider organization has a staff person familiar enough with the legacy system to make appropriate support decisions for the old system.
- Space, Power and Cooling – Machine room space is at a premium in many provider facilities, and legacy PACS archives typically occupy a large footprint. Providing uninterruptible power and cooling for these archives is also a notable expense.
- Regulatory Compliance – Many old systems are not compliant with the HIPAA Security Rule, for which the compliance date was April 20, 2005 for most covered entities (April 20, 2006 for small health plans). Legacy data must in most states be retained for 5 or 7 years. However, most PACS archives also contain pediatric cases mixed in with the adult cases, and the retention of pediatric image data to 5-7 years past age 18 is required in most jurisdictions. Mammography data, present in some archives, must in the USA be retained indefinitely. This creates an extremely long support tail for at least some of the legacy data.
- Legacy vendor Support Uncertain – The availability of support for an old archive may be poor, and is certain to become worse. Legacy support is not a key business goal of any vendor, and those support operations become harder to maintain profitably as the installed base dwindles. And finally, many vendors have been acquired, left the business or discontinued operation.
- Hardware Getting Old, Support Getting Thin – Even with the best vendor support, reliability will become more problematic as hardware and recording media (and support personnel) age. Even if the vendor maintains the support team, the development teams that they rely on for problem escalation support are long gone.
- Migration Becoming the Standard of Practice – Most provider organizations are electing to migrate their data to their new systems, enough so that it is becoming a standard of practice. As a result, it is becoming increasingly difficult to defend a “plan” to keep the data on the legacy archive until it fails and cannot be fixed, and then declare the loss an unforeseen casualty.
Need For Data Transformation
Modern PACS include productivity features, such as display protocols, that were not available in prior-generation systems. Getting the most out of these features often requires better data quality than is present in the legacy PACS. Issues such as:
- New procedure codes, consistent with RIS orders
- Mapping or “cleaning up” old procedure codes into values consistent with the new RIS
- Separation of pooled legacy data into groups separated by facility or other business factors
- Extraction of annotation and other “special” data from the legacy system and moving it into a form (sometimes proprietary) usable in the new system
Why Migration is Never Final
Even in the best of circumstances and the most thorough migration to the most “vendor-neutral archives”, migration will always be with us, because:
- Our understanding of information changes over time, and today’s data may have to be reinterpreted in light of tomorrow’s understanding.
- Our need for information changes over time. The needed format of data and the availability of metadata (header data) may be different in the future.
- And, of course, the neutral archive itself will have to be replaced in the future, and somehow the data will need to get to a new system.
However, much can still be done to reduce the difficulty and scope of future migrations. Migrating into standard formats in defined-media archives such as Semperdata™ provides significant protection from difficult migrations in the future.