LCDs & CRTs: Passing the Image Baton

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Not so long ago, film was king, and the lightbox was the display technology of choice. Then, the introduction of digital imaging modalities and picture archiving and communication systems (PACS) started many imaging centers and departments on the path toward filmless operation. Early filmless reading rooms were stocked with CRT monitors for image display. Although CRTs can be hot to operate and cumbersome to move, many radiologists grew to love them for price and image clarity properties.

Then came the introduction of the affordable LCD display. These flat-panel monitors gained early acceptance on many office desktops, hailed for their bright, nearly flicker-free displays and small footprints. But concerns about image quality for diagnostic accuracy held many radiologists back from the LCD love-fest. This is, however, beginning to change. Within the past two years, LCDs have come down lower in price and increased in image clarity, making them a viable choice for image viewing in a wide variety of settings.


Eliot Siegel is professor and vice chair of information systems in the department of radiology at the University of Maryland (Baltimore) and chief of radiology and nuclear medicine for the VA Maryland Healthcare System. He notes that, as one part of one of the first hospitals to go filmless, he has been using softcopy displays for some 11 years. He is currently working with a combination of CRTs and LCDs, and, as the need arises to replace the 5 megapixel CRTs, in come the 3 megapixel LCDs.

Obviously, the most important factor to consider when purchasing a display is confidence in diagnosis, and Siegel is confident that LCDs pass the test. "We did scientific investigations and documented the LCD is not a compromise in ability to diagnose," he says. He finds any minor differences between the 5 megapixel CRT and 3 megapixel LCD to be insignificant in daily use. "At the distances radiologists [sit] from the monitor, they can't tell the difference."

Early studies by Siegel and colleagues comparing radiologists' readings of images of lung nodules and a variety of musculoskeletal images indicate that LCD displays compare favorably with CRTs on matters of specificity, interpretation time, and radiologist's confidence on the read. (Fujifilm Medical Systems USA Inc. provided the PACS for the research study and some funding support.)

Three megapixels may not turn out to be the lower limit for LCD resolution. Siegel notes that he is "planning on doing a study with 1 to 2 megapixel LCDs, [to] look at the difference in radiologists'Ã?¢?Ã?¦ confidence in making diagnoses." The results of such investigations may ultimately indicate that lower resolution LCDs are still appropriate for diagnosis.

John Hart, a PACS administrator for Willamette Falls Hospital Diagnostic Imaging in Oregon City, Ore., also is finding strength in LCDs. He has overseen more than 40 PACS installations, and increasingly prefers LCDs to CRTs, especially in the OR or NICU.

Hart finds LCDs preferable for a wide variety of applications, even some that have traditionally been the last hold-outs for CRT. "We even do mammography under LCD," Hart says, noting that LCDs have only recently gained FDA approval for the display of mammograms. One of the hurdles has been display resolution. Mammography "requires higher resolution because so much more zoom is needed," he says. "We try to get LCDs that can do [the] 5K display required for mammography."

Not only are LCDs making inroads into mammography, Hart feels that there are certain situations in which LCDs are the only viable choice. "LCDs are a must in the OR," he says. Why? First is footprint size; "you want [your display] as small and compact as possible," he says. Second, he notes the need to maintain a cool operating room, a task that is made that much harder by the higher level of heat output from a CRT. Finally, "CRTs are well known for static [and] case leakage; you can't have [that] in the OR or NICU," he says.

This is not to say that everything about LCDs is a clear benefit over CRTs. "It is more difficult to calibrate LCDs," Hart explains. This is in part due to the composition of the screen. If you push on an LCD display, you will notice that the image will "flow" a bit as the screen depresses. CRTs, being a hard screen, are not subject to this "flow."


Once past the diagnostic confidence consideration, those considering a new display purchase