Computed radiography learns new tricks to keep up with DR

August 28, 2003

Computed radiography has been around for two decades, but it is far from obsolete. CR has stayed current by evolving new technologies and expanding into new clinical applications. But the factor that makes CR competitive with digital radiography involves

Computed radiography has been around for two decades, but it is far from obsolete. CR has stayed current by evolving new technologies and expanding into new clinical applications. But the factor that makes CR competitive with digital radiography involves the people who use it as much as the technology.

Matching staff to their tasks to cut costs and then applying those savings to technologist salaries has led to greater productivity and job satisfaction at the Lahey Clinic in Boston. CR is the digital technology of choice at Lahey, according to Dr. Anna K. Chacko, chair of radiology. DR systems also operate alongside CR at Lahey, but they are not doing as well as the staff would like.

"I was among the first advocates of DR," Chacko said. "I still believe it has potential. But our experience has been that DR is not mature enough for routine clinical application. When DR rooms are available along with CR, the technologists avoid using DR. To us, DR is a waste of real estate and money."

Opinions about the relative value of CR and DR vary widely, however. DR comes out ahead at Memorial Sloan-Kettering Cancer Center, where administrators are planning to phase out CR. The hospital installed its first DR system in December, and all chest exams are now being done on this system. The other radiography rooms will be converted to DR at the rate of one per year for the next five years, said Larry Walker, manager of general diagnostic radiology and mammography at MSKCC.

"Most of our patients have to be monitored, because they are pretty sick," he said. "With DR, techs don't have to come out of the exam room, as they would if they had to carry CR cassettes to the reader."

CR and DR are commonly employed as part of a complementary strategy to convert radiology departments to digital imaging. CR allows departments to bring portable x-ray into the digital fold, while extending the life of conventional radiographic equipment-all at an economical price. Conventional systems can then be phased out over time in favor of DR.

Since Fuji pioneered CR 20 years ago, the company has installed about 18,000 systems worldwide. Fuji, its competitors Agfa, Konica, and Kodak, and their resellers Siemens, Philips, and GE ship about 1600 units per year in the U.S., according to Clay Larsen, vice president of marketing and network development at Fuji. Demand for these products is continuing to increase. General radiography, portable imaging, screening, emergency medicine, surgery, and cancer therapy are among the major drivers.

To meet this demand, CR vendors have created families of products, some of which have automated the cassette handling and scanning within the machine itself. Fuji's upright FCR Velocity, introduced at the 2002 RSNA meeting, captures chest images and previews them in seven seconds. Velocity specifically addresses DR vendors' criticisms that CR is too slow and cumbersome.

DR technology is advancing as well. Manufacturers are developing portable x-ray units that integrate flat-panel detectors. The medical systems division of Canon USA showed such a system at the June Society for Computer Applications in Radiology annual meeting in Boston. Such systems would eliminate one of the strongest arguments for CR: DR's need to use storage phosphor plates to convert portable x-ray to digital.

Radiology departments are motivated to choose between CR and DR by the need for consistency. Nowhere is that more apparent than in the radiographic images themselves.

Radiologists reading from both CR and DR must consider the differences that the underlying technologies cause in images. Geometric magnification is considerably greater in DR than in analog or CR because the detector must be placed under the table for some exams, according to Chacko. The workaround may result in process variations that lead to higher defect rates.

Image processing software is less mature for DR than for CR, potentially resulting in higher repeat rates. This can cost more time than DR saves in cassette handling. The cost in time and money associated with handling cassettes can be avoided, Chacko said. She found that technologists at Lahey were doing tasks directly related to imaging only 57% of the time. She solved one problem by hiring "runners" who carry plates to and from the CR reader, allowing technologists to concentrate on patient management. The move not only improved productivity but cut costs, as the runners were paid only about a quarter of the hourly rate of technologists.

"We looked at the process from when patients arrived until they left, and ascertained where the roadblocks were," she said. "By the time we got CR and DR, we had improved the process significantly, which allowed us to cut back on the number of technologists."

Chacko used the cost savings from the reduced labor load to justify pay raises for the remaining technologists, which served as an incentive for them to stay at Lahey and further increase their productivity. Through these and other process improvements, revenues from radiography have increased by a factor of five, she said.

Whether implementing CR or DR, administrators should first analyze workflow in their institutions to find and remedy inefficiencies, according to Chacko. Digital technologies can then be implemented, optimizing improvements in workflow rather than possibly exaggerating existing problems. Two thirds of the potential improvement in efficiency can be achieved through process reengineering; the remaining third can be achieved through technology.

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