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Retcam II is a specialized digital imaging system for photographing and documenting patient pathologies. It relies on a comprehensive database to keep track of all digitally recorded images and facilitates transferring them via LAN or Internet.
June 05, 2007
URL:http://www.drdobbs.com/database/digital-imaging-databases-and-eye-care/199901523
Ryan McGrail is Lead Programmer for Retcam Software at Clarity Medical. He can be reached at [email protected].
Diagnosing and treating children who are at risk of going blind is tricky business. Doctors require exhaustive views of the inner eye and the utmost precision in record-keeping. Many doctors are still viewing patients' retinas through a magnifying glass (ophthalmoscope) and recording observations on paper using colored pencils. This antiquated approach, which relies on the physician's memory and subjective interpretation of hand-drawn pictures, is increasingly being replaced by the technologically superior technique of photographing and documenting patient pathologies with a specialized digital imaging system like the Retcam II.
What we've done in developing the Retcam II digital imaging system essentially brings about a 500-year leap in medical technology, "from charcoal to digital," if you will.
We knew there was a critical need for a highly sophisticated system that would allow doctors to conduct an imaging session, and review the results side-by-side with historical trend data within seconds. This would be a priceless medical tool. The other important aspect was sharing; the state-of-the-art imaging unit would have to be self-contained and mobile, to be wheeled around the clinic or hospital, and would need to let physicians share still images, video clips, and other patient data. This way, doctors could easily send visual data to a colleague for consultation, even across geographies.
Our aim was to provide a host of new functions to make capturing and evaluating visual data far easier and more comprehensive than ever before:
This system would have to rely on a comprehensive database that would keep track of all digitally recorded images and facilitate transferring them via LAN or Internet. No small order.
Two important criteria for selecting a database were the ability to store any object and to support distributed data sets. In essence, we asked, "Can the system handle our data? And is it reliable?"
The other key issue was avoiding wasting time and effort on the well-documented "impedance mismatch" that occurs when trying to use a relational database management system (RDMS) from an object-oriented program. If we chose that route, we would have faced months of painstaking data access logic coding -- as records and columns would need to be manually converted to objects and qualities. This typically results in poorly performing code that is difficult to maintain.
Our team evaluated a number of solutions, and we quickly concluded that we needed a single, reliable engine rather than a variety of technologies patched together. We ruled out the idea of using a traditional RDBMS because of the impedance mismatch issue and the fact that it couldn't accommodate our distributed environment.
We settled on db4o, an object-oriented database library from db4objects that's designed to be embedded in clients or other software components, completely invisible to the end user. db4o needs no separate installation, configuration, or setup on target machines. Rather, it runs in the same process as your application, so you have full control over memory management and can perform speed profiling and debugging over the entire system.
Using an embedded server is much more efficient from an implementation standpoint. First, it only requires a fraction of the resources that other systems would hog, since there's no need for its own separate processor or memory. (db4o has a small footprint of about 400KB). Secondly, the schema upgrades automatically when you implement new versions of your software, with no need for any form of data model update management. So an entire work package and source of errors are eliminated.
This is in sharp contrast to the labor-intensive process of distributing a MySQL or SQL Express-based system, for example.
db4o is now used to store all of the data collected in RetCam II, with the ability to accommodate up to 100,000 objects stored in one typical system database. Note that Clarity Medical Systems doesn't maintain a centralized database. Rather, each of our RetCam II units built is completely autonomous, and db4o resides within the application as a resource.
We did look at a number of alternative platforms, but db4o had the requisite key strengths:
As noted, it also helped us bypass the typical "distribution nightmare" of traditional OO databases -- the need to migrate existing (patient) data between object versions. This occurs because the code object model is usually in the data-persistence format, so any changes or re-factorings to the code between major releases also affect the database. But db4o provides automatic adjustment for updates and modifications of the object model, making it perfect for re-factoring evolving object models and updating the system with "zero-administration."
db4o is also coupled with programming languages that support reflection (Java and .NET), giving it the ability to analyze executing code during runtime. Therefore, the database has the power to support a fully dynamic software system, like a biological organism that keeps evolving, without the limitations of having to predefine data structures as necessary in RDMS.
Of course, this all happens in the background, invisible to our customers. What physicians see is a powerful new system for providing superior visualization and documentation -- allowing for earlier detection and prevention of blindness.
There are now more than 400 RetCam systems being used around the world for documenting diseases such as Retinoblastoma (eye cancer) and Retinopathy of Prematurity. The RetCam also photographs and documents retinal hemorrhages associated with Shaken Baby Syndrome. The physician then has clear wide-field images that can be printed out on a photo printer for medico-legal documentation.
Doctors tell us that because the data is being precisely recorded and stored in real-time as they conduct the examination, they've been able to find tumors (Retinoblastoma) earlier.
In addition, our customers praise the RetCam II's ease-of-use. It provides interaction through an intuitive user interface, which makes it easier to expand use beyond ophthalmologists to nurse practitioners and other medical personnel. In fact, the system's database utilities make it well-suited for use specifically as an educational tool; doctors use the stored data and images to inform and teach parents, neonatologists and other specialists, and medical students about eye disorders. This saves hospitals a great deal in costly and stressful "transference."
In our case, the choice of a native object-oriented database helped our developers save a good six months in time-to-market. But we would have easily required additional time if we'd opted for traditional SQL database; requiring cumbersome object-field mapping code for designing, building, and implementing a database schema separate from the object model.
We managed to limit or eliminate lots of the distribution and resource requirement headaches typically associated with distributed database implementation.
Time spent supporting the application is also reduced because there is simply less software to support: The database is a file on the system and a collection of objects in the code, rather than a separate, bulky server process running on each system.
In accordance with the FDA medical device and ISO 13485:2003 requirements we were required to verify and validate the integrity, repeatability and accuracy of patient data storage and retrieval. With the powerful db4o program as the backbone, we passed all these tests with flying colors.
We are pleased to be able to boast that Clarity Medical has created a system with new capabilities that are ground-breaking in the fight against eye disease. With careful selection of the right database technology, we've managed to accomplish this with minimal in-house expense and effort.
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