Computed Radiography Health Article

Systems conversion

One of the major challenges in the implementation of computed radiography in any institution is acceptance by the clinical staff. The task of retraining radiologists and technologists as well as ancillary staff can be daunting. Lastly, the increasing complexity of radiographic equipment requires greater cooperation between the engineers and scientists who develop the equipment and the health care personnel who use them. Gradual introduction of CR, along with smooth coordination of the technology experts and the clinical staff, is usually the best way of moving toward full departmental conversion.

Newer technology

An additional complication to implementing CR systems is that they no longer represent cutting-edge imaging technology. Within the past few years, a system called digital radiography, or DR, has been introduced. It resembles CR in that it transmits, displays, and stores images without the use of film, but it differs from CR in that it is strictly digital and does not use cassettes at all. While the advantages of CR include its portability and its lower production cost, DR offers superior contrast resolution, immediate image readout, and considerable time savings. The first productivity studies comparing the two imaging systems have found that a CR examination takes between three and four times as long as an examination using digital radiography. In one hospital near Boston, the average two-view chest radiograph required 9.9 minutes with a CR system but only 2.5 minutes with DR. Most of the time difference appears to be due to the steps required to process the CR cassettes. While some hospitals are using both CR and DR systems, others are concerned that CR technology may not have a long enough future in spite of its lower initial costs to justify implementing it at all.

Results

CR does, however, offer significant advantages in diagnostic quality over conventional film-screen methods. The latest enhancements for CR include energy subtraction, which makes it possible to view bone-only and soft tissue-only images of the chest, and dynamic range control, which makes it possible to study both bone and soft tissue on the same image. Another benefit of the CR system is that the images are available immediately on the monitor for evaluation and post-processing enhancement. In addition, the images can be evaluated by an off- site radiologist with a monitor hooked up to the hospital's system. Lastly, CR is a portable system that can be used at the patient's bedside or in the emergency room as well as in a radiology clinic.

Health care team roles

With computed radiography as with conventional film-screen technology, the exposures can be made by a radiologic technologist or a radiologist. The radiologist will interpret the images as part of the process of differential diagnosis. A PACS system will allow the radiolo- gist to consult with colleagues in other parts of the hospital or other institutions.

KEY TERMS

Cassette—The thin container that holds the film or the laser plate during radiographic exposure.

Digital radiography (DR)—A newer form of filmless imaging that produces digital images on a computer monitor without the use of cassettes.

Digital recording—A method of recording audio or visual data in which an input wave form is sampled thousands of times per second, and each sample is given a binary numerical value.

Film-screen—The combination of x-ray film and screens used in current conventional methods of radiographic imaging.

Phosphor—A substance that emits light when it is struck by light of a certain wavelength. Some phosphors are luminescent only when struck by ultraviolet light.

Picture-archiving communication system (PACS)—A digitized system for storing CR or DR images that replaces older film storage, manual filing, and manual routing systems.

Screen—The layer lining the cassette that changes the x-ray into light

PERIODICALS

DeMaster, Dean R. "Digital radiography offers major productivity gains over computed radiography: Results of a time-motion study." Applied Radiology 30, no. 3 (March,2001): 28-31.

Manning, D. J., et al. "An ROC evaluation of six systems for chest radiography." Radiography 5, no. 4 (November1999): 201-209.

ORGANIZATIONS

Association of Educators in Radiological Sciences (AERS). P. O. Box 90204, Albuquerque, NM 87199-0204. (505) 823-4740. Web site: <http://www.aers@att.net>.

Radiological Society of North America, Inc. 820 Jorie Boulevard, Oak Brook, IL 60523-2251. (630) 571-2670. Fax: (630) 571-7837. Web site: <http://www.rsna.org>.

Society for Computer Applications in Radiology (SCAR). 10105 Cottesmore Court, Great Falls, VA 22066-3540.(703) 757-0054. Fax: (703) 757-0454. Web site: htpp://www.scarnet.org. The Society has published the Journal of Digital Imaging since 1988.

OTHER

Page, Douglas. "Point-counterpoint: Direct and computed radiography coexist, but for how long?" Presentation at SCAR2000, annual meeting of the Society for Computer Applications in Radiology.

Van Metter, Richard, Ph.D. "The Technology Behind Digital Radiography: All Systems are Not Created Equal." <http://www.kodak.com> (January/February 2001).

Debra Novograd, B.S.,R.T.(R)(M)