Vendors of flat-panel displays address QA message at CARS

Software plug-ins address image display standards

The pace of innovation in image display systems has left regulators struggling to keep up. Quality standards for diagnostic monitors cover both the older CRT displays and high-tech LCD screens, despite well-defined differences between the two. Regulations for medical diagnostic monitors also vary internationally, adding further confusion to quality assurance.

Delegates at the Computer Assisted Radiology and Surgery 2003 meeting, June 25 to 27, debated the relative merits and need for different standards. Two stood out.

Guidelines developed by the American Association of Physicists in Medicine (AAPM) are voluntary for initial testing and ongoing quality control, whereas the DIN 6868-57 standard for acceptance testing has been the law in Germany for the past 12 months. Because of the law, German hospitals must test all new diagnostic monitors prior to use. They have until 2005 to ensure that all their monitors meet DIN acceptance criteria. (The Japanese Industry Standard on medical image display, JIS Z 4752-2-5, is similar to the German standard, but like the AAPM documentation, is only advisory.)

Germany-based Siemens offers a DIN 6868-57 plug-in as an optional extra with its automatic calibration tool (SMfit ACT). The plug-in supports acceptance testing, constancy testing, and automatic reporting.

Planar Systems of Beaverton, OR, released a similar plug-in option last month. The product, which complies with DIN 6868-57, forms part of Planar's newly released CXtra 3.0 software, which is supported by all flat-panel monitors marketed under the Dome CX brand. The upgrade is free to all existing customers under Planar's guarantee to provide ongoing QA. Radiologists who do not even work in Germany will likely download it, said David Hebert, marketing manager for Planar's medical business unit.

"The German DIN standard is attracting a lot of interest throughout the EU," he said. "Many countries that do not have compliance standards for display quality are adopting DIN 6868-57, so it is actually considered a pan-European standard."

But adherence to today's legalities is not the end of the story, according to Hebert. Planar's flat-panel systems pass through a rigorous calibration process before leaving the factory. The panels also have an embedded photometer, which continually checks that luminance levels fall within DICOM recommendations. The internal calibration tool does a better job of monitoring QA, but the DIN test plug-in reassures customers that their image display is appropriate for diagnostic work.

"We support DIN because it is the law in Germany, and it is a good standard to be able to look at the quality of displays," Hebert said. "We are committed to building tools that allow our customers to feel comfortable with that quality and prove that quality to anyone who would question it, such as a government agency or even their colleagues."

Belgium-based BarcoView, which stayed away from CARS this year, has marketed an optional DIN 6868-57 testing module with its MediCal QA management software since early 2002. A product oriented toward AAPM guidelines is also in the pipeline, although these recommended standards are not likely to become part of U.S. law, according to Danny Deroo, product and R&D manager for BarcoView's software products.

Existing regulations for image display do not yet provide a comprehensive QA guarantee, he said. Control of ambient light in reading rooms, for instance, which is not covered by spot photometer tests or review of gray-scale patterns, is crucial, whatever type of monitor is being used.

A new International Electrotechnical Commission (IEC) workgroup is now looking in detail at QA for image display systems to produce a standard that will be recognized in more than 30 countries, he said. The committee met for the first time in May 2003 and will probably take 18 months to complete its work, by which time display technology may well have advanced again.