What Is Computed Radiography?


The development of computed radiography has made examination, diagnosis and treatment in the fields of medicine and dentistry safer as well as more informative. The equipment also is used for safety testing in such disparate areas as the spacecraft industry, automobile manufacturing and other industrial areas. Computed radiography is used now in preference to the older style film X-rays for non-destructive examination and restoration of art works and in archeology for the study of artifacts.


Traditional radiography, in use since its invention in 1885, stores images on a photographic plate. Computed radiography can use existing X-ray equipment to take pictures but stores the images on a plate with phosphors that are activated and retained when the image is taken. A laser is used to scan the plate, which is converted to digital format. The results are then fed directly into a computer for interpretation. This simplifies the whole process since no photographic development process is involved, meaning no dark rooms are necessary.


The equipment for computed radiography ranges from small portable scanning devices to large, floor standing machines that can process more than 200 images per hour. Complete systems include a display unit, keyboard and computer used in conjunction with the scanner. A typical layout in a hospital involves a patient staging area, one or more X-ray rooms, scanners and processors for the conversion to digital images. If computed tomography (CT) systems are in use as well, these will be situated so that image processing can feed into the conversion equipment.


Instead of having to take multiple images with older equipment, by using digital imaging computed radiography reduces the amount of radiation to the body and often allows the physicians to see everything they need on a single exposure. Because of the digital nature of the images, there is no degradation from continual viewing as there can be with X-ray film. Other advantages include more finely focused results from the process as well as greater placement accuracy, which leads to less need to re-do exposures.


An alternative to computed radiography introduced in the last decade of the twentieth century may at some point replace the older system. Digital radiography (DR) can provide improved resolution of images and is faster. However, DR cannot use existing X-ray equipment and requires a separate room for each unit. A computed radiography device can handle four different X-ray rooms. The cost differential for DR systems is significant, being at least three times more than the cost of a single computed unit. Computed radiography is a mature technology, which was developed in the middle years of the twentieth century. It is in use in medical centers around the world. In many cases it has replaced the process of taking X-rays on film by a way to produce digital images. With these, better quality scans are possible, in shorter times, and with wider availability for study. The technology is found not only in medicine and dentistry but in other areas, such as manufacturing for safety testing and analysis.