Computers and radiology: stepping into the digital future.
Continued development of computed radiography (CR) systems is spurred by radiology administrators' need for these advantages.
In the United States, consolidation of health care systems into integrated delivery networks is creating desire and demand on behalf of health care providers to transmit radiographic images electronically for rapid remote viewing and consultation.
While film images can be digitized, they still require chemical processing and darkrooms, and the digitization process itself adds steps to the workflow.
We view the future of radiography as a hybrid environment that will combine film-based systems, computed radiography and some form of digital radiography.
As digital technologies including computed radiography advance, they approach the resolution advantage held by general radiographic film.
Given acceptable diagnostic quality, it makes sense to capture images digitally if those images are going to be electronically distributed and stored.
The digital image can be printed on film for viewing and/or diagnosis as needed, so a digital imaging system certainly presents an intriguing opportunity to health care providers.
The emphasis in the development of CR technology today revolves around the size of the hardware and the diagnostic quality of the images.
In the past 15 years, CR technology has evolved from an experimental concept into a modality with great promise, especially for portable applications. In the early 1980s, prototype CR products were installed in university institutions with an emphasis on research.
By the late 1980s, commercial CR products were installed in selected hospitals where radiology administrators were eager to test this new technology.
Today, computed radiography systems are viewed as an effective and efficient method of delivering radiographic images in critical care imaging where demanding conditions made it difficult for radiographers to obtain consistent image quality on radiographic film.
In this application, the wide dynamic range provided by a CR system generates images with excellent diagnostic value. Currently, several hundred CR systems are installed in U.S. hospitals, primarily in critical care and emergency departments.
During its technological development, CR hardware has become much smaller. Some systems today are the same size as a radiographic film processor. Radiology administrators embrace these compact systems as a means to save space, while reducing the need for darkrooms.
CR systems are becoming more viable because the radiation dose, which was once several times that of screen/film techniques, is now comparable.
Improvements in storage phosphor materials, image processing software, optical collecting systems and laser scanners combine to boost the sensitivity of modern CR systems. Some manufacturers are in their fourth or fifth generation of development.
Image quality issues
While the radiation dose of CR systems is comparable to film-based systems, spatial resolution is not.
The spatial resolution of a general screen/film system is 7 to 8 line pairs per millimeter.
The spatial resolution of CR systems is often less than half that, ranging from 2.5 to 5 line pairs per millimeter.
In the majority of applications, CR does not perform as well as film in the spatial resolution category, but it is a clear leader in the area of contrast resolution, which also impacts the diagnostic utility of images.
The wide dynamic range of CR systems, combined with the ability to adjust levels of brightness in the image, gives radiologists the ability to see structures that cannot easily be detected on radiographic film. With film, the contrast is determined by the composition of the film, the radiographic technique and the chemical processing.
CR has proved its ability to provide acceptable -- and in some applications, superior -- images to screen/film systems.
A primary advantage of computed radiography is noted in portable and critical care imaging, where the wide dynamic range characteristics of CR reduce the number of repeat exams required due to inaccurate technique adjustment or pathology. CR also provides the ability to provide rapid electronic image distribution.
Both of these characteristics are especially useful in a critical care setting.
We expect dramatic changes in radiology in the coming years, including widespread use of digital technologies.
Radiology departments may apply screen/film, CR and digital radiography systems to various applications, determined by the requirements of each.
Thin-film transistor digital radiography is one of the more promising technologies for radiology.
With thin-film transistor technology, an array of transistors converts X-ray energy to an image. Data are collected by electronic scanning of the transistors. Unlike CR, phosphors or X-ray converting overcoats may or may not be involved, and there is no need for a laser to scan the imaging plane.
This technology offers potential for gains in productivity because there is an expectation that technologists no longer need to carry cassettes to a processing station area.
This paves the way for radiology administrators to consider reengineering the radiology department processes with a focus on achieving improved efficiencies.
Charged coupled device (CCD) technology is an alternative for direct digital capture.
Many manufacturers, for example, use this technology in digital imaging systems designed for use by police departments, forensic laboratories, bridge inspectors, and professional and amateur photographers.
It's important to point out that the ultimate success of any digital radiography system lies not only in the capabilities of the capture system, but also the abilities of image processing software which ultimately defines the image and formats it for viewing.
Over the long term, digital radiography will likely evolve as stand-alone chest imaging systems and digital X-ray tables.
Through this evolution, CR systems will continue to be utilized for mobile X-ray applications as customers seek avenues to create the-all-digital department.
The ability to digitize a film image and transmit the electronic image to remote sites will continue to serve as a cost-effective means of teleradiology while CR and DR technologies continue to evolve.
In the future, radiology administrators will be able to apply a variety of digital imaging technologies, including computed radiography, according to the needs and requirements of the imaging application, patient and imaging environment.
Michael Moehring, R.T. (R), A.R.R.T. is a marketing and product line manager for computed radiography systems developed by Kodak's Dallas-based Health Imaging Division. Prior to joining Kodak 13 years ago, he worked in radiology, administration at Decatur Memorial Hospital, in Decatur, Ill. At his request, his honorarium for this column will be donated to the Susan G. Komen Breast Cancer Foundation, Dallas.
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|Title Annotation:||Technology Information; computed radiography|
|Publication:||Health Management Technology|
|Date:||Dec 1, 1997|
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