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DDR or CR?
For some the best choice is both

BY QAMAR ZAMAN

As medical practice moves closer to an all-digital environment, healthcare organizations face the challenge of acquiring leading-edge technology while budgets shrink under market pressures and cuts in government compensation levels. At Loyola University Medical Center, our market share was growing and we needed to quickly acquire new technology. We calculated that the three-phase plan we developed would migrate us to a total PACS environment in three to five years.

Loyola, a large, tertiary-care teaching facility, is located in Maywood, IL, a western suburb of Chicago with rapid population growth. Loyola's physician network was designed to increase market share by increasing the number of referrals to the facility.

Referrals for all types of services have increased, with our radiology department growing 8% to 10% per year in volume, outstripping the ability of our x-ray file room and existing diagnostic x-ray equipment to cope.

Particularly hard-pressed by the increase was the medical center's already-busy orthopedic practice. Loyola is building an expanded ambulatory care center on campus that would further increase the volume of outpatient radiographic studies. In addition, we were seeing an increase in the use of imaging in conjunction with a greater number of surgical and other procedures. The need for more productive technology was urgent.

As a large academic medical center performing about 220,000 procedures a year at multiple sites, Loyola had a serious problem with film storage, filing, and routing. Storage takes an enormous amount of space and the wholly manual filing process was time-consuming and fraught with potential for error. Films could be mislaid or retained by clinicians rather than being returned for filing and reuse by other clinicians. Digitizing existing film and capturing all future images digitally seemed the answer.

So we embraced the total PACS environment as the best route to increased productivity and improved image handling and storage, even as we perceived the general trend by the radiologic industry toward a filmless future.

Loyola was already well on the way to an all-digital radiology service. MRI, CT, nuclear medicine, ultrasound, and angiography were already digital. Ultrasound was augmented with a miniPACS. And a computed radiography unit was installed in the pediatric ICU.

We decided that, as Loyola's analog chest x-ray units reached the end of their useful life, they would be replaced by some form of digital technology, and we considered digital radiography (DDR) and computed radiography (CR) systems. Both technologies fitted our goal of an entirely digital diagnostic x-ray function, though we favored DDR because it did not require an intermediate step (the phosphorous plate) to attain image capture.

Price became the decisive factor in the mix of CR and DDR technology that we ultimately chose. To immediately replace all analog units with DDR units at a cost of several million dollars was prohibitive. We purchased three Kodak CR 800 DirectView single-plate CR units for use with our portable and emergency department x-ray equipment and one multiplate Kodak CR 400 Plus autoloader unit for the main hospital's radiology department.

For the outpatient clinic, where high patient volume justified the fastest system we could afford, we opted for a DDR system to replace the analog chest unit, and after several site visits to examine different types of DDR equipment, we bought the DDR Multi-System, a direct digital radiography system from Swissray.

INPATIENT SOLUTION

The Kodak CR 800 unit is equipped with a 14-inch, flat-panel, full-color touch screen with an image matrix that produces sizes from 18 x 24 cm to 35 x 43 cm. Images are produced from a storage phosphor plate and are processed in less than 60 seconds, following insertion of the reusable CR cassette into the CR unit. Images can be reviewed at the CR unit or passed through to a laser imager, diagnostic workstation, or archive. A barcode reader is included for patient/cassette/exam identification.

Both Kodak CR units comply with HL7 and DICOM 3.0 standards. The 400 uses Kodak Digital Science image-processing software. From an input of cassette and patient ID, body part, and projection, the software creates image segmentation on the region of interest, builds a visually optimized tone scale, performs edge enhancement, applies a blackened surround mask, and optimizes the tone scale before forwarding the image to a viewing workstation or laser printer.

The CR 800 unit uses Kodak DirectView EVP software. The software divides image data into low- and high-frequency component images. The low-frequency component image's contrast is reduced to increase latitude, while the high-frequency component image is enhanced to preserve detail. The images are then combined to produce one high-quality image.

OUTPATIENT SOLUTION

The DDR Multi-System uses a digital detector (the Add-On Bucky) equipped with four CCD arrays to capture image data directly in a digital format. The four arrays overlap to capture all relevant imaging data.

The display monitor allows image manipulation, such as positive/negative display and zoom; adjustments to brightness, contrast, windowing and latitude reduction, region of interest (ROI), noise reduction, and edge contrast; and postprocessing adjustments. The open-architecture software complies with HL7 and DICOM 3.0 and allows for connectivity to primary-read workstations, archives, HIS/RIS, and Web-based viewing stations.

UNIQUE BENEFITS

CR technology enables the creation of digital images for applications not currently served by DDR technology, such as portable studies. And the relative affordability of CR units compared with DDR enabled us to immediately implement digital technology to further our PACS strategic plan and increase productivity within our current budget.

We adopted direct digital technology to improve productivity, and the ddRMulti-System has more than met our expectations. Our outpatient throughput increased more than three-fold because the system eliminates film-processing time and retakes. Because the image captured by the DDR unit is displayed in seconds on the workstation monitor, the technologist knows instantly whether the proper position has been captured. Then the patient can leave. Any fine-tuning of the image can be done at the technologist's leisure.

Patients appreciate being able to move swiftly through the outpatient clinic, and technologists using both CR and DDR units appreciate being freed of the burden of multiple x-rays to achieve an acceptable image.

We also can print as many films of the CR and DDR images as needed—an essential function, since we can't yet store the digital images for more than about a month.

While we have not eliminated full-time employees as a result of CR and DR implementation, we have been able to provide more services within the medical center without adding staff—for example, providing technologist support for Loyola's new lithotripsy unit.

We have considered future benefits of these two technologies as well, and have chosen DR technology as the predominant technology for our diagnostic x-ray department. DDR technology can produce images with better resolution than CR units, and the superior speed of DDR technology over CR technology—a few seconds as against about 90 seconds—can prove a significant service advantage, particularly in the emergency department, where efficient throughput is critical.

CHALLENGES REMAIN

Installation of the Swissray unit was targeted for February 2000. In preparation, we formed an installation team of Loyola's in-house imaging engineering group, appropriate physician representatives, technologist supervisor, radiology manager, radiology administrator, and installation specialists from Swissray.

Because the footprint of the DDR unit was smaller than the room in which it would be housed, virtually no physical modification was needed. The unit required no special air conditioning or environment controls. We were able to prepare the room to receive the DDR unit in two weeks, at minimal cost.

Initial unit installation, software set-up, calibration, and technologist training were done in a week. The support specialist from Swissray helped bring the system online and stayed for two days to answer questions, but installation and operation of the unit presented some problems.

Image quality was compromised due to some incorrect algorithms, and the vendor's specialist had to come back to fix those problems. In addition, the unit did not communicate seamlessly at start-up with DICOM 3.0-compliant systems in our network. We had to modify the systems to establish communication, and this process is continuing.

As part of Loyola's strategic plan for radiology services, the medical center will be bringing the new radiology information system online within the next year and plans to establish a long-term archival system to drastically reduce manual file handling and storage space.

Loyola's vision for its PACS environment allows clinicians, clinical instructors, and medical students to gain electronic access to any image, anywhere, and at any time. DDR and CR technologies have moved us one step closer to making that a reality.