From Left: The Canon CXDI-50G portable DR system is designed for general radiography, trauma, and bedside care; Hologic’s ImagePro allows the user to stitch two to five DICOM images; The Works-in-progress system consists of a computer, monitor and stitching software.

Digital radiography (DR) systems have been available for several years. They are nearly synonymous with high-tech, highly productive radiography. But a third high—the acquisition cost of these systems—has limited DR installations mostly to large hospitals and university research centers...until now. Outpatient imaging centers and low to mid-volume hospitals are starting to purchase DR systems. Srini Seshadri, general manager of surgery, x-ray and interventional imaging for GE Medical Systems (GEMS of Waukesha, Wis.), explains, “It’s not a question of size, it’s workflow. We all know there is a shortage of technologists, nurses and radiologists. Size and patient population don’t matter. Anything to make imaging faster, easier or better is good for the customer.”

Apparently, lower-volume sites and imaging centers have not only picked up on this reality, but are making purchasing decisions based on it. The result, says, Bill Healy, vice president and general manager of DR Systems for Hologic Inc. (Bedford, Mass.), is that digital is growing faster than anyone predicted. In fact, Healy claims that some industry sources underestimated the growth of DR by a factor of two or three.

So, DR systems are selling, but just what are buyers buying? “The big premise for any hospital considering DR is the ability to take data and do something useful with them,” says Seshadri. And DR is certainly proving its utility. DR converts report tremendous gains in productivity. These gains are made possible by reduced exam and image delivery times. Studies show that exam time is reduced by up to 62 percent compared to film or computed radiography (CR), and image delivery time is reduced by a startling 98 percent compared to analog. Patient transport personnel at M.D. Anderson Cancer Center (Houston) joke that turnaround time is so fast with the hospital’s DR system they no longer have time for a coffee during imaging runs.

Productivity is certainly key, but it isn’t the only gain associated with DR. DR also can free up valuable space within the hospital as a DR room can handle more volume than an analog room and actually replace two analog rooms. And there is the superior image quality of DR. Finally, DR has some cachet within a community, enabling early adopters to attract technologists, referring physicians and radiologists in the ever-shrinking radiology labor pool.

Many sites are well acquainted with these factors. What they are looking forward to is the next generation of DR. What innovations are vendors bringing to the DR table to tempt sites clinging to film-screen and computed radiography? They are launching an entire cornucopia of innovations including advanced applications, powerful software enhancements and a portable DR system.

DR goes portable
For years, DR sites have been plagued by an irrefutable fact of digital life: these systems can’t be moved throughout the hospital. In many DR sites, the hospital’s most critical patients, those who cannot be moved from their bed, are imaged with a CR system. So, in this otherwise highly productive facility, a technologist sets out on rounds with a handful of cassettes. After imaging two or three patients, the technologist returns to the CR reader, develops the cassettes and QAs the images. The entire process can take 10 or 15 minutes or longer. All too frequently images are not good because it is very difficult to image patients in bed. In those cases, the technologist needs to return to the patient for additional images — a loss of productivity for the tech and an inconvenience for the patient who must be repositioned to undergo a second or third procedure. The upshot? “Hospitals have all been waiting for portable digital imaging,” says John Allen, national sales manager for Canon Medical Systems (Lake Success, N.Y.).

Canon recently launched the Canon CXDI-50G, a large-area portable DR system that can be used at a patient’s bedside. The system is designed for diverse applications including trauma and bedside exams; it combines a large, 14-inch by 17-inch imaging area with a lightweight design (10.6 pounds), extending the range of exams that can be completed with DR. The system is large enough for chest and abdominal X-rays, and it can be easily positioned for lateral or axial imaging of limbs or other areas.

The ability to bring DR to the patient’s bedside is a tremendous plus.

Bedside radiography is difficult and time-consuming, and it can be uncomfortable for the patient who needs to undergo multiple exams for a good image. The Canon CXDI-50G provides quick and efficient access to images. The technologist can preview images in three seconds, and total image processing time is a mere 20 seconds. In addition to immediate preview capabilities, the CXDI-50G is able to store more than 1,000 images. “That means,” says Allen, “that the technologist could make rounds with one panel and image as many patients as needed. The tech could finish rounds with a single panel or even complete a full day’s worth of studies with it.”

Hospitals and nursing homes that opt for the Canon CXDI-50G can expect to reap huge productivity gains. That’s because techs can immediately retake an image at the patient’s bedside if necessary. Allen predicts, “Productivity gains could be 50 percent at a very efficient hospital, or gains could go as high as 1,000 percent at some sites.”

There are other benefits to the system as well. The increased productivity and efficiency means that hospitals don’t need to dedicate a full staff to portable imaging, which saves both financial and human resources. And finally, patient care is improved, as the patient does not need to undergo multiple x-rays.

The Canon CXDI-50G joins the company’s other portable DR plate — the CXDI-31. That system features a 9 x 11-inch sensor and is used for neonatal, pediatric and orthopedic work. Many of Canon’s current portable sites will be able to opt for field upgrades to the CXDI-50G. The company started shipments of the CXDI-50G in July.

Both the CXDI-50G and Canon’s other new DR offering, the CXDI-40C Premium DR System, feature an amorphous silicon flat-panel sensor. The CXDI-40C adds a cesium iodide scintillator and a very high detective quantum efficiency (DQE), which enables the system to transfer all captured radiographic information with almost no degradation. The new system provides very high-quality images while reducing radiation exposure for the patient. It features a 17-inch x 17-inch imaging area and is available in multiple wall stand and table configurations. Canon expects the CXDI-40C to be available this summer.

Flexible, friendly DR
As hospitals and imaging centers transition into digital radiography, they are wisely considering the entire structure of the system — not only the room but how the images will be utilized. They don’t want a one-size-fits-all solution, nor do they have to settle for a universal product.

Hologic’s Epex offers variable SID and articulating arm of bucky unit permits greater imaging flexibility. The bucky has 52-inch vertical travel.

Hologic’s answer to this dilemma is the recently launched Epex family of digital systems. Epex digital systems share a number of common components including a newly designed operator console, upgraded system software, generator, detector support tower and Omniflex overhead tube crane. This allows users to select a system built around a fixed or mobile table with or without a wall stand, utilizing a single or two-detector configuration. Healy explains, “The Epex component strategy allows users to pick the system best suited for their particular needs.” Some of the more popular combinations are the Epex ER, a single-detector DR system with a choice of mobile stretchers, and the Epex Symphony, a two-detector solution with table and tilting wall stand detectors.

The detector wars
While some vendors have clearly focused their efforts on delivering new DR hardware, other vendors are opting for a different approach. Hologic, for example, continues to stand by and tout its amorphous selenium direct capture technology. Jim Culley, marketing manager for DR systems for Hologic, notes, “Selenium direct capture is really emerging as the preferred system. It’s gaining a lot of support. Siemens Medical Solutions USA Inc. (Malvern, Pa.), Agfa Healthcare (Ridgefield Park, N.J.) and Philips Medical Systems (Bothell, Wash.) have partnered with us to use direct capture technology in their DR systems.”

Amorphous selenium directly converts x-ray photons into an electric charge and omits the need for intensifying screens, intermediate steps or additional processing to capture and convert the incident x-ray energy. The selenium camp maintains that other DR systems use an indirect conversion and a two-step process for x-ray detection. Scintillation materials such as cesium iodide or phosphors such as gadolinium oxysulfide capture x-ray energy and convert it to light, which is then converted to electronic signals via an array of thin-film diodes. These intermediate steps can result in light scatter and an intermediate spreading signal profile; both can degrade image quality.

Andy Mack, marketing manager for GEMS, counters that amorphous silicon cesium iodide detectors are very efficient at stopping x-rays and converting them to an image, and selenium is not as good at stopping or absorbing x-ray. He adds that the question of direct vs. indirect conversion technology is focused on how energy is transformed not on the performance of a system. DQE is the standard for quantifying digital x-ray quality; it measures contrast and noise with the ideal theoretical DQE standing at 100 percent. A head to head DQE comparison may be a better way to approach the detector and conversion issues. And it is an issue well worth considering. Healy concludes, “The only piece of DR hardware that makes a difference is the detector. After that, it’s is all software.”

The next frontiers: software and advanced apps
Hospitals and imaging centers recognize the productivity gains associated with DR, and they are sorting through the nuances of different detector technologies. The next frontiers for many vendors are software and advanced applications that can help solve problems associated with film-screen radiology.

Seshadri explains, “One of the most notorious problems of film screen radiology is a lung nodule superimposed over a rib or behind a pacemaker.” GEMS touts a new advanced application that can be paired with its Revolution DR system to minimize these types of issues — dual-energy subtraction.

Dual-energy subtraction eliminates the problem of overlying bones obscuring chest pathology. How does it work? Standard high-energy PA and low-energy images are acquired less than 200 milliseconds apart. The low-energy image is subtracted from the high-energy image to produce both bone and soft tissue images. This can have dramatic ramifications on patient care. For example, a physician at University Hospitals (Cleveland, Ohio) using dual-energy subtraction reports that the technology impacts patient care two or three times day; he has indeed found a mass behind a pacemaker with the technique.

Dual-energy subtraction is one example of an advanced application. One point hospitals should consider as they shop for a DR system is that at least some of these advanced applications can hinge on the type of detector in a DR system. GEMS’ Revolution detector has been engineered to accommodate dual-energy subtraction, other advanced applications and future works-in-progress. Features critical to these applications include high DQE with wide dynamic range and high-contrast resolution, fast frame rate acquisition and readout, and ultra short exposure-to-exposure times.

Another new advanced application from GEMS is tissue equalization. Some anatomical regions are difficult to visualize with standard film-screen radiology. Tissue equalization smoothes the digital image without losing the underlying pathology; an algorithm permits the display of both low density and high-density tissues in a single view. The technique has a long list of advantages. Image quality is excellent, and patient dose is lower (by about 40 percent, according to several studies). Moreover, it delivers more diagnostic information without the need for window/leveling, which improves radiologists’ productivity.

A related offering from Hologic is the company’s new IT-Plus software, which features an optional Inverse Topography tool that allows users to expand the visibility of low-contrast structures such as tissues and vessels, while maintaining and enhancing the visibility of high contrast bony structures. The software also enables users to review and display images using a number of different processing algorithms; the final image can be displayed with a DR look, a CR look or a screen-film look.

There are scores of other problems associated with either film screen or digital radiography. Scoliosis exams, for example, cannot be completed without stitching. A solution, however, is in the works. Hologic’s DR Image Pro Image Stitching Solution is currently in beta testing. The system consists of a workstation and software that is used to stitch together two to five DR images for imaging situations where the desired field of view is larger than the 35 x 43 cm size of the image receptor. The software includes functions used to interactively stitch together the images, and measuring tools for the merged images while the workstation features a toolkit with standard image processing functions.

The image stitching process demonstrates the power and utility of DR software. The protocol consists of a series of x-rays with a 2 to 5 cm area of overlap between successive exposures. After image acquisition, the images are sent via the PACS to the system workstation. Common points of anatomy in the images are identified, and the stitching algorithm translates and rotates the images to maximize registration of overlap of the common points. A single output image can be displayed, printed and archived to the PACS as one large image.

A final consideration with DR is service. Seshadri notes, “Along with the digital transformation of radiography products is the transformation of service and the ability to interface over the Internet.” GEMS DR solutions are live on broadband 24/7; customers can access call center personnel to fix systems issues, assist with applications problems and download new software-based applications.

Canon systems come with a one-year warranty and can then opt for a range of extended service contracts or full 24/7 service. Hologic offers four service and support plans for its products; options range from telephone support to on-site assistance 24/7.

Into the future
Now that DR vendors have committed to various detectors and tapped into software solutions, where is DR headed? The answer should surprise few in the radiology community. Healy says, “At some point CAD will come into the picture. It’s probably the next frontier.”

GEMS, for one, is boldly exploring that frontier. Last year, the company signed an agreement with Deus Technologies (Rockville, Md.) to develop a digital CAD product for lung cancer for use on GEMS’ DR systems. [GEMS has a similar alliance for mammography CAD with R2 Technology (Sunnyvale, Calif.).] The Deus CAD system identifies regions of interest on chest images that may have features associated with solitary pulmonary nodules, which may lead to earlier detection of lung cancer. One advantage of digital CAD is better integration into the radiologist’s workflow. GEMS expects that the new digital CAD product will be available later this year.

Portability, flexibility, software, advanced applications and CAD capabilities are excellent additions to the DR portfolio, but the real story behind DR remains the same. It is the ticket to unparalleled productivity in an environment that demands it.