By George Scott
High-resolution grayscale monitors are the lynchpin of any PACS network. Yet researchers have expressed concern about the short lifespan and frequent service needs of high-resolution monitors used for primary diagnosis. A study led by Dr. Eliot Siegel and conducted by the University of Maryland School of Medicine and the VA Maryland Health Care System showed that actual monitor lifetimes fell far below anticipated and expected lifespans.
According to the study, "During the 17-month period during which the vendor’s maintenance records were reviewed …83% of the high-resolution monitors suffered a major hardware failure. This represents a failure rate of … 59% per year, with an average time until a major repair of 1.7 years."
While these failures certainly represent Siegel’s experience, the results seem almost unbelievable. How could failure rates be so high?
The high-resolution grayscale monitors used in PACS have a singular purpose -- to accurately and consistently display images. If it's true that monitors do not remain stable and reliable over a reasonable period of time, then quality control programs become even more crucial.
While parallel efforts are underway by the American Association of Physicists in Medicine (AAPM) to clearly define quality control standards, responsibility ultimately falls to the monitor manufacturers to meet the expectations and demands of the market. This article outlines some of the considerations related to the costs of owning high-resolution CRT monitors, as well as the demands placed on monitor manufacturers as a result of industry requirements.
In a perfect PACS world, the ultimate high-resolution monitor would arrive precalibrated, require no installation or maintenance, maintain image consistency over time, and have a long life with almost no user intervention required. However, given that the ideal is unattainable, what is an acceptable level of performance?
It's clear that both institutions and industry must implement standards to ensure that established performance levels are maintained over the useful life of the monitor. However, there's a big difference between quality control and quality assurance. In order to move away from the reactive need to continually control monitor performance, and move into a proactive mode of periodically assuring conformance, improvements in design are necessary.
Assuming that price levels are generally equalized in a competitive environment, most initial purchase decisions are made on the basis of image quality. Adequate image quality is extremely important to the proper display of images, and the monitor selected must be capable of a wide contrast range and good focus distribution. The next question -- how well does a monitor perform over time? -- can be broken down into two main areas: stability and reliability.
Next page: Monitor stability
