(CR) Computed radiography is an imaging technique that uses similar equipment to conventional radiography except that films are replaced by imaging plates. An imaging plate contains photostimulable storage phosphors, which store the radiation level received at each point in local electron energies. The imaging plate is placed under the patient in the same way as conventional film cassettes. After x-ray exposure, the imaging plate is run through a special scanner to read out the image. The digital image can then be processed to optimize contrast, brightness, and zoom. Computed Radiography can be seen as halfway between film-based conventional technology and current direct digital radiography.

Decimation is the reduction of data at the digitized signal. Fewer samples are used to represent the detected signal. The opposite process is called interpolation, more samples are added.

See also Digital Radiography, and Digital Subtraction Angiography.

When invented, a fluoroscopic system consisted of x-ray tube, fluorescent screen and x-ray table. In 1950's, the development of the image intensifier revolutionized fluoroscopes. The basic components are extended by a gantry, image intensifier, camera, film and monitor system. The x-ray tube is usually located under the patient table, in opposition to the image intensifier and film cassette or display unit. The patient table can be rotated to an upright position for certain examinations and can be lowered to horizontal position for other imaging procedures. In some instances, the unit can be operated from outside the room.
Today, the transition from conventional to digital fluoroscopy replaces the image intensifier. A flat-panel detector in combination with sensitive image sensors and digital image processing improves the diagnostic ability of a modern system.

An imaging plate is used in computed radiography (CR) instead of a conventional film cassette.
The imaging plate is coated with photostimulable phosphors. The phosphor layer is doped with special substances to alter the crystalline structure and physical properties. After radiation, the enhanced phosphor material absorbs and stores x-ray energy in gaps of the crystal structure, building a latent image.
Usually, the storage phosphors are stimulated with a low-energy laser to release visible light at each point of x-ray absorption. To read-out the image, the plate is inserted into a computed radiography scanner. The scanning laser beam causes the electrons to relax to lower energy levels, emitting light that is captured by a photo-multiplier tube and converted into an electrical signal. The electronic signal is then converted to digital data and can be displayed on laser-printed films, workstations, transmitted to remote systems, and stored digitally.
The CR units automatically erase the image plate after the complete scan. Phosphor imaging plates, like film, are stored in cassette format and can be re-used very often if they are handled carefully. Existing conventional x-ray equipment, from generators to x-ray tubes and examination systems, can be used with imaging plates.

(PACS) Picture Archiving and Communication System is an IT-based storage and retrieval system for digital images.

See also Radiology Information System and Digital Imaging And Communications In Medicine.