DICOM Data Warehouse: Part 2

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Abstract
In 2010, the DICOM Data Warehouse (DDW) was launched as a data warehouse for DICOM meta-data. Its chief design goals were to have a flexible database schema that enabled it to index standard patient and study information, modality specific tags (public and private), and create a framework to derive computable information (derived tags) from the former items. Furthermore, it was to map the above information to an internally standard lexicon that enables a non-DICOM savvy programmer to write standard SQL queries and retrieve the equivalent data from a cohort of scanners, regardless of what tag that data element was found in over the changing epochs of DICOM and ensuing migration of elements from private to public tags. After 5 years, the original design has scaled astonishingly well. Very little has changed in the database schema. The knowledge base is now fluent in over 90 device types. Also, additional stored procedures have been written to compute data that is derivable from standard or mapped tags. Finally, an early concern is that the system would not be able to address the variability DICOM-SR objects has been addressed. As of this writing the system is indexing 300 MR, 600 CT, and 2000 other (XA, DR, CR, MG) imaging studies per day. The only remaining issue to be solved is the case for tags that were not prospectively indexed—and indeed, this final challenge may lead to a noSQL, big data, approach in a subsequent version.