The logistics of launching a quality-control program for workstation monitors discourage many sites from ever getting a QC effort off the ground. For others, designing a QC program is easy-it's the follow-through they find hard to do.

It's not unusual for administrators to create elaborate QC test modules only to disband the effort after a few months. Limited staff resources are the most commonly cited cause, said Dr. Manuel Arreola, director of clinical radiological physics at the University of Florida-Shands Health Care in Gainesville. Lack of a defined objective for the QC program-such as creating a reliable replacement schedule for costly high-resolution monitors-can also doom the effort.

Without question, testing and tweaking display monitors is a tedious chore. High-resolution displays need to be regularly calibrated and adjusted to ensure compliance with the demands of image interpretation. Manual testing can only be performed one monitor at a time, sapping staff resources.

There's also some confusion over just how much quality control is needed. Several documents exist to guide monitor performance, from the American College of Radiology's digital image management standard to the DICOM gray-scale standard display function (DICOM Part 14). New guidelines released by the American Association of Physicists in Medicine's Task Group 18 (TG18) provide yet another benchmark.

DUELING GUIDELINES?

The AAPM guidelines evolved out of the association's assertion that assessment of electronic display devices falls within the rubric of medical physicists and their supervised QC staff. Creation of the TG18 document was also motivated by concerns that few guidelines exist for display quality testing in a clinical setting, and that those available are either too complicated or too subjective, said Ehsan Samei Ph.D, an assistant professor of radiology, physics, and biomedical engineering at Duke University Medical Center.

Samei, a member of the AAPM workgroup that created TG18, reviewed the document at the 2003 Society for Computer Applications in Radiology meeting in Boston. The TG18 document is a guideline only, and it is fundamentally different from DICOM Part 14, said Elizabeth Krupinski, Ph.D., an associate professor of radiology at the University of Arizona in Tucson.

"DICOM Part 14 has more to do with how monitors are calibrated so that they display what the human visual system can see," she said. "It makes the image perceptually linearized; the gray scale is optimized to match that visual system."

TG18, on the other hand, provides a series of techniques for measuring specific characteristics, such as luminance, uniformity, resolution, noise, veiling, and glare, she said. The guidelines also go into detail about how to evaluate the quality of various physical parameters that could affect the overall appearance of the display.

PRACTICAL PARAMETERS

The comprehensive nature of the TG18 document has drawn accolades from PACS experts. But Arreola worries that the guidelines could prove too rigorous for sites lacking onsite physicists to implement them.

He devised an "accessible, efficient" monitor QC program geared for sites with budget and staffing constraints. The testing process takes about 15 minutes per monitor and can be performed quarterly, using existing staff.

"TG18 is a wonderful document, and it's exactly what needs to be done in terms of evaluating displays in a way that looks at all the important parameters," Arreola said. "However-and this is a big however-in order for an institution to implement it in any realistic way, you need a physicist on staff."

Moreover, the TG18 guidelines take time to implement. If a facility followed the 150-page TG18 document to the letter, it could take a junior physicist up to an hour or more per monitor per month to do, he said.

Another alternative is to install software, which is available from monitor manufacturers, that automates some or all aspects of the QC process. Both Planar and Barco offer products that continuously monitor display luminance and DICOM conformance and allow administrators to remotely manage the performance of networked displays.

MAKE A LIST, CHECK IT TWICE

Any QC effort-even one that relies on vendor software-should begin with a good grasp of monitor inventory, Arreola said.

"You can't have a good QC program if you don't know where your monitors are, where they have been, and how they are being used," he said.

But establishing an inventory list can be a monumental task, particularly for a institution like Shands Health Care, which maintains about 220 workstation monitors across the six-hospital, four-clinic system. Without such a database, however, Arreola said, sites fall into "remedial mode," simply replacing displays when they fail.

Just as critical to creating an inventory database is designating a staff person who will be responsible for maintaining it. At Shands, an in-house service department has been charged with this duty. Another option is to enlist the services of a technologist who has some QC training. That same person can also assist with the actual testing effort, Arreola said.

The next step is designing a test procedure that is representative of display performance but can be performed quickly and easily. At Shands, Arreola relies on some DICOM Part 14 recommendations for luminance response, resolution, contrast detectability, and other parameters that gauge overall performance. This visual assessment also incorporates the use of the SMPTE (Society of Motion Picture and Television Engineers) pattern, although Arreola expects that aspect of the test will soon change.

"We might migrate this year to some of the patterns that TG18 has developed for contrast and resolution," he said. "Unlike SMPTE, TG18 separates the assessment of different parameters by using different visual patterns."

After tracking display testing and performance on a weekly, monthly, and then quarterly basis for more than two years, Arreola found that quarterly assessments provide the same value as more frequent checks, an important piece of information for sites that could spend staff time on other tasks.

When Shands shifts to a primarily flat-panel display environment within the next two years, the frequency of testing could decrease to every four or even six months.

While a facility like Shands has the staff and resources to fully implement TG18 guidelines, the average radiology department may just be transitioning to the digital environment. It's those sites that face the biggest challenge when it comes to implementing a practical QC program, according to Arreola.

"They are the ones who really suffer and who don't have the budget to replace 10 monitors per year," he said. "A QC program that does the job, but is not overly simplistic, is going to get these departments out of remedial mode and into proactive mode."