Selective Projection Imaging: Applications to Radiography and NMR

Projection imaging has traditionally been plagued by intervening structures which limited the visibility of the desired regions. This problem was solved by the cross-sectional format of computerized tomography. This format, Manuscript received at 1982. however, exhibits relatively limited field of view, poor resolution and high dose. It is particularly unsuitable for the important problem of vessel imaging. In this paper we study selective projection imaging, a technique for isolating the desired structures in the projection format. In digital radiography, using temporal or energy subtraction, these techniques have shown excellent capability of imaging important structures. These techniques appear particularly applicable to NMR where, unlike the X-ray history, primarily cross-sectional images have been produced. In particular, because of its sensitivity to moving material, NMR appears ideally suited to vessel imaging. ntroduction