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CR vs. DR: Competitive or complementary technologies?

By Michael J. Cannavo

The author is president of Image Management Consultants of Winter Springs, FL. He can be contacted at pacsman@ix.netcom.com

Healthcare facilities embarking on PACS and wanting to go completely filmless are often faced with a choice between computed radiography (CR) and direct radiography (DR). While both technologies have their virtues, it¨s not always easy to determine which is best in a particular setting. A strategy for converting to digital x-ray should take into account the clinical applications for which the modality will be used, image mix, trends in procedure volume, staffing, and room use. For radiologists, the choice between CR and DR is largely based on technical factors, most notably image quality. Each technology has its supporters and detractors. There are also camps that endorse the competing DR technologies!^direct ̄ amorphous silicon systems versus ^analog ̄ CCD-based systems!just as there are devotees of a particular CR vendor¨s line pair resolution, post-processing algorithms, and technologist interface. For chief financial officers, however, the purchasing decision usually skips right past the technology and comes down to money. Let me explain. The painful fact is there¨s no difference in reimbursement between radiographs made by a conventional film-based system and those made by CR or DR. It¨s obvious, therefore, that the most cost-effective digital x-ray system is the one that usually gets the nod. But determining cost effectiveness can be tricky. While DR can legitimately boast higher throughput based on enhancements in technologist workflow, CR with at least moderate throughput can be shared between two rooms, allowing

for a major reduction in per-room costs. This is a critical factor for most radiology departments. Five CR units at a cost of $200,000 each ($1 million total) can handle upto 10 rooms (if adjacent to one another) and easily take the place of $4 million worth of dedicated DR rooms (10 systems at $400,000 each). Service costs are also reduced with CR. DR supporters note that DR can shave two minutes or more from a 10-minute general x-ray exam due to process changes over CR or analog film. Let¨s examine this argument. If you reduced FTEs by 20% (two staff positions), you could possibly save up to $100,000 in salaries per year. This is a far cry from the $3 million disparity in the purchase price between CR and DR described in the scenario above. Even if we were to translate the two minutes in potential time-savings into additional revenue (representing a 20% increase in general radiographic volume), DR would still not break even. This assumes the facility does 100,000 general radiographic (GR) procedures per year and has net collected revenue for the technical component of $45 per study. This assumption also requires the facility to convert 100% of that saved time into procedures!which never happens!and to show a 20% growth rate for GR procedures. Unfortunately, few facilities are experiencing growth in GR. Volume has actually declined slightly at most facilities as new applications for MR and CT continue to emerge. CR is typically a hands-down favorite from an economic standpoint, given that a CR system is priced at less than half the cost of a dedicated DR room and can be shared by two rooms. Multiple CRs in a department also provide for the redundancy needed to maintain operational efficiency and security. Many CR units provide higher throughput than the rooms in which they are installed can handle, so having available redundancy raises the confidence of end-users.


A key consideration in selecting a digital x-ray system should be the technologist interface. A well-designed interface can reduce the throughput differential between CR and DR by 50% or more, and save up to three minutes per study over conventional film processing. This is a critical factor, given the persistent technologist shortage and the need to optimize existing technologist resources. The interface varies dramatically between systems, however, so it¨s important to have the chief technologist on the CR evaluation team to provide input on this. So where do CR and DR fit, respectively, in the PACS environment? DR is best used in high throughput settings where several patients per hour can be accommodated using a table or dedicated chest unit. CR can be used in the same settings as DR, with the added flexibility of performing x-rays from remote locations, such as in the emergency department, and doing exams that cannot be done with fixed equipment, such as extremities studies. If additional reimbursement for DR were made available, the argument between CR and DR would become more technical than cost-related. Until this happens, however, CR appears to provide much better value for thosechoosing digital x-ray technology.


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