Katherine P. Andriole, PhD, associate professor in the UCSF department of radiology, and two of her colleaguesDavid M. Luth and Robert G. Gould ScD conducted an assessment and comparison of CR vs DR and screen-film in terms of workflow, productivity, speed of service, and potential cost-justification for the imaging of ambulatory outpatients.

"We reached the conclusion that both DR and CR can improve workflow and productivity in an outpatient environment, but DR requires high volumeat least 200 examinations dailyto be cost effective over CR," Andriole summarizes.

To make this determination, Andriole and her team surveyed UCSF's radiology technologists for their perceptions of each modality's ease-of-use and impact on workflow. They also measured productivity as the rate of patient throughput from normalized timing studies. Overall speed-of-service was calculated from the time of examination ordering as stamped in the department's radiology information system (RIS), to the time of image availability on PACS, and then to the time of interpretation rendered from the RIS.

"The comparative results of screen-film analog vs a CR reader and a DR dedicated chest unit show a higher patient throughput for the digital systems," Andriole says.  "A mean of 10.7 patients were moved through the DR chest room per hour, and 9.2 patients per hour using CR, vs 8.2 patients per hour for the analog device. Measured time-to-image-availability for interpretation is much faster for both DR and CR vs screen-film, with the mean minutes to image availability calculated as about 5.7 minutes for DR, 6.7 minutes for CR, and 29.2 minutes for screen film.

"Also, image quality is nice for DR because its detector is more efficient and therefore allows for more signal to be collected, but spatial resolution is the same as CR. And, while I believe that CR and DR are going to coexist for a very long time, the results of our study don't support the notion that CR will be replaced by DR as the better solution for achieving distributed radiology."

Rich Smith is a contributing writer for Decisions in Imaging Economics.