Applied Radiology

In the summer of 2000, Indiana University Hospital (IUH), Indianapolis, IN, became one of the first facilities in the country to install a digital radiography (DR) system. IUH is a 350-bed hospital that is part of the Clarian Health Partners hospital system. A year earlier, the hospital decided it needed to replace outdated x-ray equipment in its chest exam area. Radiologists and hospital administrators agreed that the timing was right to convert to a digital capture system that would integrate well with the PACS (picture archiving and communications system) that is planned for installation by the end of 2001.

The hospital had successfully installed several computed radiography (CR) systems but decided to evaluate the new DR technology. A DR system would offer even greater productivity improvements and the potential for higher image quality.

DR technology

DR describes projection radiographic systems that capture an image with an embedded detector. That image is then read electronically to produce a digital image. Image files are viewed and adjusted, as needed, by technologists to ensure optimal image quality prior to releasing the image. Images can be routed automatically to PACS systems for soft copy review by radiologists, or can be transmitted to local or remote sites for review or output to film.

Several different technologies have been applied in DR systems. Direct detectors automatically convert x-ray photons into electronic signals and produce precise signal profiles and resolution. Indirect detectors have an added step: they first convert x-rays into light, and then convert the light to electronic signals. In the process, light scatter tends to degrade the signal profile and resolution.

IUH product selection

Dewey J. Conces, Jr., MD, Clinical Director of Radiology at IUH, assumed responsibility for evaluating and selecting the DR equipment (figure 1). At the 1999 Radiological Society of North America meeting, he investigated systems, interviewed vendors, and viewed sample images. He then reviewed charts of Detective Quantum Efficiency (DQE), Modulation Transfer Function (MTF), and Nyquist frequencies for several different DR technologies.

"After reviewing the scientific studies and looking at the images, I determined that the direct detector technology held clear advantages," notes Dr. Conces. "The higher Nyquist frequency and MTF found with direct detector technology enhance visualization of fine detail and provide superior imaging performance."

Since several companies market the direct-detector technology selected by Dr. Conces, Stanley Metzger, administrative director at IUH, assumed the task of selecting a vendor.

"In my mind, the expertise and resources of the vendor are as important to a successful implementation as the quality of the technology," he said. "This is a long-term investment for the institution. We selected Kodak because it was the only vendor that offered a history in imaging, long-term stability, excellent service and support, and the best technology available."

The hospital purchased and installed a Kodak DirectView DR 5000 (Eastman Kodak, Health Imaging Division, Rochester, NY).

Benefits of DR at IUH

Dr. Conces is convinced that the DR 5000 system has improved image quality. "After six months of use, we can confirm that the Kodak DR 5000 system provides greater clinical detail than our previous film-screen system."

In addition to providing enhanced image quality, the DR system has also increased productivity. At IUH, patient throughput has increased 60% since the installation of the DR system, according to Metzger. He attributes this increase to the system's 10-second preview and 35-second cycle time speed (figure 2), in addition to the time saved by the elimination of processing and related activities for film or CR cassettes.

Another feature that saves time is the fact that exams can be taken in the order that requires the least patient movement. When working with film, technologists usually capture views in a prescribed order so that they don't "lose their place."

"The ability for a technologist to capture a digital image, select a patient's name on the monitor, and perform quality control on the image in seconds is a revolutionary step forward," Metzger reports. "In addition, technologists don't need to leave the patient to process cassettes or check the images--it's all done at the system's operator console. And that's a tremendous advantage as well."

Staff training and support

As with any leading-edge technology, training and support are critical elements to a smooth implementation.

"It took about a week to get familiar with the equipment and the process. After several weeks, our technologists had forgotten all about film and processors," Metzger observes.

Training on the DR system takes just a few hours for technologists. Since patient positioning is the same, technologists just need to learn the screen commands on the operator console. The DR 5000 offers an easy-to-use interface that was designed with customer input, so all terms and phrases are familiar to users. Since the screen commands are customized to each facility's exam process and naming convention, the technologists continue working with the same terms they have used before. For example, one hospital might use the term "accession number" while another uses "patient ID number."

The specific views most commonly included with chest studies are preprogrammed as well, so the screen prompts the technologist with the views that are to be captured. As each view is captured, a thumbnail view of each image is displayed on the screen.

Kodak also provides online monitoring of the DR system, which allows off-site engineers to detect and correct any technical issues before they can cause problems.

Part of an overall digital plan

While many facilities are still evaluating the merits of DR technology, Dr. Conces and Metzger both believe it fills an important role.

"Converting the radiology department to a digital platform requires implementing either CR or DR technologies, or a mix of both, as we have chosen," says Metzger. "CR offers flexible digital capture at a reasonable price. As such, it's ideal for portable exams, such as in the Emergency Room and Intensive Care Unit, and other low-volume areas."

He also believes that DR technology has broader applications. "We believe that the gains in productivity and image quality that DR offers in high-volume environments offset its current price premium."

Metzger is satisfied with the choice IUH made for their radiology department. "Kodak's DR system offers an excellent combination of image quality and productivity in a digital capture platform," he explains. "We believe this is a compelling package for any progressive health care institution."

The installation of the DR system at IUH has been so successful that a second Kodak DirectView DR 5000 system has been installed to perform chest radiographs at the 775-bed Methodist Hospital, the largest facility in the Clarian Health Partners network. AR