The purpose of this research is to demonstrate the value of transition radiation in angiography. Within this area of diagnostic radiology, the specific interest is centered on the development of a non-invasive method of coronary angiography based on the use of monoenergetic x-rays at energies close to the K-absorption edge of iodine. In the past, both conventional and synchrotron sources have been used. Unfortunately, the conventional sources lack monochromatic x- ray beams of adequate intensity, while the cost of a synchrotron source is prohibitive. The specific motivation for the proposed studies is an urgent need to reduce both the risk and cost of coronary arteriography. The proposed method involves the acquisition of radiographs at x-ray energies slightly above and below the k-edge in iodine at 33.16 keV and the subsequent digital subtract of these two images to achieve maximum contrast in the visualization of the intra-arterial iodine. The high brightness and laser-like collimation of transition radiation make it an ideal source of x-rays for medical applications. This source has received a relatively small amount of attention as a x-ray generator of high brightness. Yet the radiation per electron is several orders of magnitude greater than synchrotron radiation, and, as demonstrated in Phase I of this program, a moderate electron beam of 100 to 500 MeV can be used, whereas a synchrotron source requires electron energies of 3 GeV or greater to obtain 30 keV photons. Transition radiation is a cost effective source of hard x- rays for non-invasive angiography for the detection of coronary disease; lithography for the production of integrated circuits; x-ray analysis of biological material; and high resolution medical x-ray of organs such as kidneys and heart.
