Time savings may not support DR purchases by low-volume users

Fuji plans educational tools incorporating new data

The rivalry between digital radiography and computed radiography has hinged largely on money, specifically which modality provides the biggest financial advantage. Now two studies, one at the University of California, San Francisco, the other at the Baltimore VA Medical Center, may have documented the conditions under which these technologies do best.

The UCSF study examined CR and DR, comparing them both to screen-film. Researchers looked at workflow, technologist productivity, overall speed of service, and potential cost-justification for imaging ambulatory patients.

"Our timing studies indicate that DR improves patient throughput over CR in a high-volume outpatient clinic, and that both DR and CR achieve higher patient throughput than screen-film," said Katherine Andriole, Ph.D., of the UCSF radiology department.

During the study, DR handled a mean of 10.7 chest exams per hour. CR handled 9.2 exams per hour and screen-film 8.2.

Measured time to image availability for interpretation was much faster for both DR and CR than for the analog screen device. UCSF calculated 5.7 minutes (± 2.5) for DR, 6.7 (± 1.5) for CR, and 29.2 (± 14.3) for screen-film. The increased productivity, however, may not justify the higher cost of DR versus CR, particularly during periods of sporadic patient flow.

"The time saved with DR may not currently justify the increased cost of DR for low-volume situations," Andriole said.

CR and DR went head to head in a Baltimore VA Medical Center/University of Maryland study. The objectives were to determine time and performance differences in chest radiographic exams when using CR and DR, while also identifying critical workflow steps that could be optimized for productivity gains.

The prospective time-and-motion study included 81 randomized patients (40 CR, 41 DR) undergoing a two-view chest radiograph. Researchers collected data points for patient preparation time, patient positioning time, exposure time, and quality control time.

No statistically significant differences for patient prep or exposure times were observed, although DR was slightly faster, according to BVAMC radiology technologist Steve Severance.

"Statistically significant differences were demonstrated for patient positioning time and quality control time," he said. "Positioning time for DR is almost half that of CR because technologists have to load a fresh plate after the first image, which they don't have to do using DR."

DR technologists spent very little time on quality control compared to those using CR, because the DR image is immediately available at the console, whereas CR images could be viewed only after the plate was read. This was time consuming, because the BVAMC reader was located 30 to 50 feet down the hall from the exam room.

"Of the total time differences between DR and CR, 81% was accounted for by QC differences," he said.

Solve the QC problem and the time differences between the two technologies are minimal, said John Strauss, director of marketing for Fujifilm Imaging Systems. The way to do that is to site a CR reader in each exam room. This has become financially viable now that the price of some CR systems has dropped to less than $100,000. This would be an especially attractive option, Strauss said, if an institution with four radiography rooms, for example, had recently invested in new screen-film systems and wanted to protect that investment.

"These rad systems last 15 years," he said. "So if they spend $400,000, they can put a CR reader in each of these rooms as opposed to taking one room digital with DR."

Fuji CR systems were used in the UCSF and BVAMC studies--and Strauss plans to put the data that came from both studies to work for Fuji, possibly in the context of a video presentation that shows CR and DR operations.

"We've got the productivity quantified, now we're going to develop educational tools that will show people how these technologies work so they can understand what it means," Strauss said. "These will become educational resources for sites to better plan for their unique requirements."