Backscatter x-ray radiography: Medical applications

A new x-ray perspective and tomographic imaging technique which employs the field backscattered by an object has been demonstrated to have interesting medical applications. The resulting radiographs appear as if the objects’ internal features were interrogated by an “x-ray eye.” Uncollimated detectors are placed on the same side of the object as the incident radiation. A flying spot technique creates a backscatter image. Spatial resolution of the system is dictated by the diameter of an x-ray beam which raster scans the object under study. One millimeter resolution at penetration depths of several centimeters of tissue equivalent material is demonstrated with the use of short pixel dwell times to achieve radiation dose levels of the order of 10 mR. A system which generates real time x-ray backscatter images was constructed and used to examine biological and test objects. Two modes of image formation have been employed: 1. The unusual perspective of an x-ray backprojection of internal features. 2. The differentiation of different peak voltage scans to obtain longitudinal tomographic images. The system is sufficiently practical with several medical x-ray sources that medical diagnostic radiography could immediately derive benefit from the changed point-of-view.