(CR) a system for replacing photographic film with a charged plate. Exposure to X-rays knocks charge off the plate. The resultant image can be read by a laser beam and stored digitally or printed out as required. This system is widely used in conjunction with *PACS systems.
A radiological technique for detecting osteoporosis (see BONE, DISORDERS OF) in which a beam of X-rays is directed at the bone-area under investigation – normally the spine and hip – and the CALCIUM density measured. If the calcium content is low, preventive treatment can be started to reduce the likelihood of fractures occurring.... quantitative digital radiography
(CT) a form of X-ray examination in which the X-ray source and detector (CT scanner) rotate around the object to be scanned and the information obtained can be used to produce cross-sectional images (see cross-sectional imaging) by computer (a CT scan). A higher radiation dose is received by the patient than with some conventional X-ray techniques, but the diagnostic information obtained is far greater and should outweigh the increased risk. CT scanning can be used for all parts of the body. The data obtained can be used to construct three-dimensional images of structures of interest. See also multidetector computerized tomography; spiral CT scanning.... computerized tomography
(DR) an alternative to film radiography, by acquiring X-ray images from a large number of individual X-ray detectors on a matrix in a digital format directly. This contrasts with *computerized radiography, in which an *analogue image is taken and then put into a reader to be converted into a *digital image. The technique allows the storage of images and their subsequent retrieval, manipulation, and interpretation using computers (see PACS).... digital radiography
(MDCT) a development of *spiral CT scanning that uses more than one array of detectors opposite the X-ray tube, so that more tissue can be included, with thinner cuts, in a single rotation of the machine. This is particularly important for three-dimensional reconstruction of tissues. It also allows volumetric scanning or *isotropic imaging, which are best achieved when the thickness of the slice is similar to the size resolution of the detectors in the other two planes. Modern CT scanners are now usually equipped with between 16 and 640 detector arrays. The technique is particularly valuable for imaging fast-moving structures, such as the heart.... multidetector computerized tomography
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