Exploring your digital radiography equipment options
Making the leap to digital radiography? You have two basic types of equipment to choose from. Now, which one is right for you?
Dec 01, 2006
One of the first steps in switching to digital radiography is deciding which type of system to purchase. Two broad classes of digital radiography equipment are available for veterinarians: computed radiography (CR), which is cassette-based, and direct (capture) radiography (DR).1,2
CRCR was the first digital radiography system used in medical imaging. CR systems have many features analogous to those of traditional film-screen systems (Figure 1) because a cassette is used to house a photo-stimulable phosphor sheet.2 CR radiographs are obtained in a traditional manner: all the views of the study are taken, and then the cassettes are moved en masse to a digital processor. Each cassette is then individually fed into the processor where the storage phosphor sheet is removed and scanned by a laser (Figure 2). The laser imparts energy onto the storage phosphor sheet, liberating light from the latent image stored therein. The light emitted from the phosphor sheet is digitized to produce the digital radiograph.
Thus, the CR workflow is similar to that of traditional radiographic film.4,5 Because of the delay in image processing, it will take several minutes to identify errors in radiographic techniques, specifically positioning. For small-animal practice, this may simply entail repositioning the animal. But mobile practitioners won't recognize the need for retakes until the cassettes are returned to the processor, which is most commonly housed in a stationary location such as the clinic.
CR requires purchasing the cassettes, a processor, and equipment for viewing and storing the images (see the article "Getting the most out of digital image viewing" and the article "How to store digital images and comply with medical recordkeeping standards" ). The cassettes have the same physical dimensions as film-based cassettes and do not require any modification to the X-ray generator, tables, or grids. In general, CR is a slightly less expensive digital radiographic modality that will provide many of the advantages of digital imaging in a veterinary practice.