Use of electromagnetic radiation to produce images of internal body structures for diagnosis. X-rays have been used since 1895. Denser tissues, such as bones, absorb more X-rays and show as lighter areas on X-ray film. A contrast medium can be used to highlight soft tissues in still X-ray pictures or can be followed on X-ray motion-picture films as it moves through the body or part of the body to record body processes. In computerized axial tomography, X-rays are focused on specific tissue planes, and a series of such parallel “slices” of the body are processed by computer to produce a 3-D image. The risks of X-ray exposure are reduced by more precise techniques using lower doses and by use of other imaging techniques. Seealso angiocardiography; angiography; magnetic resonance imaging; nuclear medicine; positron emission tomography; ultrasound.
Learn more about diagnostic imaging with a free trial on Britannica.com.
NCQDIS has three primary objectives:
Today, NCQDIS represents more than 2,400 outpatient diagnostic imaging centers and departments throughout the United States. Through affiliated professional societies, the NCQDIS message reaches over 150,000 centers and professionals involved in the provision of diagnostic imaging services. Medical imaging equipment and supply vendors support NCQDIS as well. NCQDIS has undertaken a number of important initiatives on behalf of the diagnostic-imaging industry.