When moving to a digital environment for radiology images and reports, healthcare institutions have to address how or whether to bring paper records and hard-copy films into the digital realm. But planning for the future integrity and smooth migration of digitally stored images and reports to subsequent data management systems may be just as important.
With patient record and medical image retention times likely outlasting the life of the systems that store the data, all PACS and RIS users will need to upgrade or convert to a new archive at some point, according to Fred Behlen of the University of Chicago’s department of radiology. And responsibility for successfully accomplishing that task ultimately resides with the purchaser of the system.
"Helping you move to another vendor’s system at the end of its service life is not that previous vendor’s problem, it’s yours," Behlen said.
Behlen presented the University of Chicago Hospital’s recent experience in migrating PACS and RIS archives to newer systems at the annual Symposium for Computer Applications in Radiology, held in June in Philadelphia (Journal of Digital Imaging, Vol. 13, No 2, Suppl 1(May), 2000: pp. 171-174).
For 14½ years, the hospital used a homegrown RIS, a descendant from the Missouri Automated Radiology System (MARS) written in MUMPS programming language. They now wished to upgrade to a QuadRIS network from ADAC HealthCare Information Systems of Houston.
At the same time, the hospital wished to move two years' worth of PACS image data (MR, CT, and chest CR images stored on its legacy robotic DLT library from Martin Marietta) to a robotic tape library from Storage Technology. The new archive employed the vendor’s 9840 tape drives and ASM hierarchical storage-management (HSM) software. The hospital had about 2.4 million MR and CT images (600,000 MB), and approximately 115,000 CR images (750,000 MB) in its previous archive.
For the MR and CT images, the hospital had maintained backup DLT tapes containing their DICOM information objects, and elected to use an image-sending program to transfer them into the new archive’s DICOM software. Needing to decommission the archive before Y2K, the hospital had to transfer the CR images in a two-step process, first moving the images to DLT media from the legacy archive’s virtual file system. The image files on the HSM software were then input to the new archive HSM software using the same process as the MR and CT images.
The PACS conversion was achieved quicker than expected, Behlen said. The MR and CT data was successfully transferred in 20 days, while the CR images were converted and indexed in six weeks. For the sake of speed, Behlen recommends that images stored on off-line storage be transmitted in the order they are stored on the tapes, rather than using some other criteria, such as by alphabetical order.
"DICOM does not provide a way for you to find out the order that will be most efficient for you to ask (images files) to be transferred in," he said.
The RIS conversion process did not go quite as smoothly, due to the lack of standardized information models among RIS vendors, Behlen said. Of the nearly 2 million signed reports and related data earmarked on the legacy RIS archive, 3% did not successfully transfer. More than 56,000 records still remain out of the database, awaiting troubleshooting, Behlen said.
A number of problems became evident in the transfer, which was accomplished using file formats specified by ADAC. First, there was information -- such as first names of referring physicians -- required on the new system that were not included in the old system, requiring the insertion of dummy text, Behlen said. In some cases, data included in the old system -- such as multiple radiologists contributing to one case -- could not be supported by QuadRIS, he said. Also, the two information systems had different methods of indicating order status and date sequencing, causing more headaches.
Migrating data between different radiology information systems poses significant challenges, due to the lack of standards for such transfers, Behlen said. Ultimately, Behlen believes this situation poses a threat to the long-term integrity of RIS information.
"Information modeling efforts underway in the DICOM and HL-7 standards organizations are promising," Behlen said. "But we’re going to need more involvement in standards development from the radiology and vendor communities."
With all the challenges inherent in successful and expedient data migration, PACS purchasers should make data migration an important buying consideration, Behlen said. Systems that store images using DICOM Part 10 file formats and industry-standard media directories should be favored, he said.
"Those will offer you a lot of data migration options in the future," he said.
By Erik L. Ridley
AuntMinnie.com staff writer
September 19, 2000
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