Computed Radiography Equipment
Computed Radiography is very similar to the procedural method of conventional radiography. The Image Receptor is a cassette with special Image Phosphors mounted inside. The cassette is positioned in the very same manner as conventional X-ray, either table top or table/wall bucky. Once the X-ray button has been pushed, the phosphors will capture X-ray photons that pass through the patient and hold onto them. The cassette with the phosphor plate (and recorded image) is then sent through the CR Reader. Inside the reader, a laser will energize the phosphors and they will release the photon energy. The energy emitted is captured by an analog digital converter, and sent to the computer as a "digital radiograph".
CR is the least expensive method "to go digital" and for some time has been the preferred method for hospitals because one reader can support multiple rooms without replacing X-ray equipment.
CR is the choice method of "going digital" for private practice physicians. The system simply replaces the processor, darkroom, and all of the costly consumables that are needed with conventional radiography.
The DR plate is a series of horizontal and vertical wires that compose a matrix to receive X-ray photons after they pass through the patient. The plate is mounted either in the wall or under the table to receive the image. Once the X-ray button is pushed, the photons will penetrate through the patient and gather in the small squares or pixels. The number of photons in the square determines the darkness of the pixel on the image. The photons are "read-out", and the digital radiography appears on the monitor in less that 6 seconds.
Digital Radiography is usually the most expensive method of "going digital" but it also affords the highest quality image because the X-ray photons are directly producing the image. In the Digital Flat Plate Technology, there is no medium as in CR with cassettes or CCD technology with the conversion of light energy.
The plates are expensive to make, and are frequently purchased as a single Image Receptor. The Plate is usually tethered to a cord that is connected to the computer and must be moved from the table bucky to the wall bucky for upright imaging. Some have considered this the weakest link in Digital Flat Plate Technology. Today, Kodak as well as others are receiving FDA clearance for wireless transmission which will eliminate the cord.