Radiographic stereoplotting. A new technique and its application to the study of the spine.

Radiographic stereoplotting is a method for taking three-dimensional measurements from a pair of x-ray films. The x-ray technique is described, as is the stereoplotter. Using this machine it is possible to locate any point within the patient and measure the distance between that point and any other point. From this information it is possible to compute areas, volumes, and angles with great accuracy, which hitherto has been impossible using noninvasive techniques. It is planned to take measurements of the spinal canal in normal backs and in patients with nonspecific back pain, in order to try to define some of these syndromes on a structural basis. It is likely that stereoplotting has some useful application in most branches of clinical medicine, since the x-ray technology is available in any diagnostic x-ray department.