Computed Radiography (CR) was first introduced in 1982 but was not widely used until the early 1990’s. CR uses the exact same x-ray sources as conventional radiography; the difference is the use of a photostimulable storage phosphor plate to create the image instead of film. The CR image plate is scanned and digitized using a CR Reader which produces the image. This image can be viewed and enhanced using software that allows the technologist to change the brightness and contract as well as other image features.
Direct Radiography also known as Direct Digital Radiography (DR) began it’s popularity in the late 1990’s with multi-plate detectors that plot and convert the image for viewing using proprietary software. Today most DR systems employ a single direct detector that produces and image almost instantaneously upon x-ray exposure.
Both CR and DR allow the user to manipulate the image prior to transmitting to a QA, PACS or Diagnostic workstation. The question is which system provides the biggest benefits and versatility for the Radiology environment. DR easily proves to be the faster of the two based on the almost real-time image production while CR requires the technologist to scan the phosphor image plate to create the image. CR requires more conventional type processing but it’s much more versatile than the X-Ray Room based or C-Arm style DR units.
Similar to conventional film and cassettes, the CR image plate and cassette can go to where the patient is using a portable x-ray machine. This is very helpful in the case of emergency or surgical radiography. Although a growing number of emergency departments and surgical suites are requiring DR technology to be built into their treatment tables, CR or cassette based imaging is a requirement for mobile and portable x-ray exams.
I’m sure the future will reveal more portable style DR units with the ability to leave the Radiology department and the flexibility to provide instantaneous x-ray images from anywhere in the hospital. Until then we will have to count on a combination of CR & DR to provide the most benefits and flexibility for radiology operations.