PACS QA: What you see is what you beget

Because quality criteria for PACS have not yet been standardized, institutions are left to wrestle with the components that contribute to systemwide quality mostly on their own.

Understanding quality assurance of PACS workstations is especially important now that the trend away from CRT to LCD monitors has gathered steam.

"How you approach a flat-panel world is different from a CRT world," said Dr. Jeffrey B. Mendel, chair of radiology at Caritas St. Elizabeth Medical Center in Boston.

The types of artifacts that users run into with LCDs are different, and the causes and solutions are different, he said.

Many experts agree that flat panels will soon replace CRTs completely in PACS.

"We just put in a three-hospital PACS, and we have no CRTs whatsoever," Mendel said.

Mendel has given a PACS quality assurance course at the RSNA meeting the past few years. He advises institutions to carefully assess their monitor needs before beginning to shop for PACS.

If they then codify those needs into a document for doing acceptance testing, they will have a continuum - from what they are looking for to what they are contracting for to what they need to test for.

"They will then know that what they thought they were getting is what they got," Mendel said.

QA is also important because most PACS have both diagnostic-quality and clinical (nondiagnostic) workstations on their networks.

"Clinical workstations don't need to be dedicated, high-quality medical-grade monitors. But without an assessment of monitor needs before purchase to determine what criteria are actually needed, you can end up with videocards that can't be calibrated," he said. "So you can never make the images look good."

When that happens, clinicians sometimes pester radiologists because they don't have a monitor showing the detail they need for their own evaluations.

QA programs are also essential because monitor quality can degrade so gradually it may go unnoticed.

The joke is, the only time radiologists complain about monitor image quality is when they can't read the patient's name, Mendel said.

In order for radiologists to efficiently read eight hours a day off a PACS workstation, all quality measurements need to stay at a high level. Before PACS, radiologists could tell if a film was good quality just by looking at it. No more.

"With computer-based systems, it isn't enough to just look at the image to know whether the quality is there. To make sure you are getting the data, you need a rigorous QA program in place, to verify that the quality of the image you see is the best it can possibly be," Mendel said.