The risks and costs of the present method of visualizing the coronary arteries have limited the use of coronary angiography in long-term serial studies needed to establish the natural history of coronary atherosclerosis and its response to interventions. A less invasive method, in which the contrast agent is administered intravenously, has been developed using synchrotron radiation as the illuminating source. The present report describes the initial results in human subjects. The findings indicate that transvenous coronary angiograms can be acquired in this manner. Further refinements in the x-ray imaging system are expected to result in increased x-ray fluence and improved image quality.

https://www.pnas.org/content/pnas/83/24/9724.full.pdf

Transvenous coronary angiography in humans using synchrotron radiation.

A multilayer x-ray reflector or reflectors are used with a source of radiation for narrow bandwidth or dual energy radiographic imaging applications. In one aspect, a unique multilayer design permits two distinct x-ray energies of narrow bandwidth to be reflected at the same incident angle for use in dual energy applications. In another aspect, several multilayer reflectors are employed in a slit scanning system. In yet another aspect, an elongated radiation source and a multilayer x-ray reflecting structure are combined to provide an x-ray or gamma ray source.

Apparatus for narrow bandwidth and multiple energy x-ray imaging

The number of patients due to ischemic heart disease seems to be growing rapidly in Japan. Coronary angiography by Judkins' or Soncs' method is very invasive as is well known and thus imposes a burden on patients and physicians. The K-edge subtraction technique is considered to be applicable to intravenous angiography of coronary arteries. A feasibility study of K-edge subtraction with monochromatized SR has been initiated at Photon Factory since 1984. In 1985, a real time observation of intravenous angiography of a cat, utilizing a monochromatic beam with a size of 64 mm by 55 mm, was performed. This paper describes some results of our preliminary experiments and our future systems of clinical application.

An attempt at coronary angiography with a large size monochromatic SR beam

K-edge subtraction synchrotron X-ray imaging in bio-medical research

The performance characteristics of conventional and K-edge filters have been studied for the entire field of general diagnostic radiology. The problem of optimising the conflicting needs from patient dose, image contrast and exposure time was managed primarily by computer simulation. In comparison to conventional filters like iron or copper no significant advantages can be obtained with K-edge filters in practice except for the special circumstances of automatic fluoroscopy. The optimal choice of conventional filters is discussed. The different roles of backscattered radiation for skin dose and integral dose are demonstrated, and the necessity of correcting for increased backscatter following additional filtration is stressed. The potential for dose reductions by adding filtration has been found to be substantially smaller than the figures mostly reported. Finally some methodological problems of studies of this kind are pointed out.

https://iopscience.iop.org/article/10.1088/0031-9155/34/9/012/pdf

Comparison of performance characteristics of conventional and K-edge filters in general diagnostic radiology

The intense synchrotron radiation produced at electron storage rings provides a new source of X-rays highly suited to iodine K-edge digital subtraction angiography. The high intensity and small angular divergence permit the radiation to be monochromatized by Bragg diffraction and made available in beams of small vertical size, of arbitrary horizontal width, and of tunable energy. The use of such beams provides maximum sensitivity to intra-arterial iodine and virtually eliminates image contrast due to non-vascular body structures. The sensitivity of this method to iodine offers the prospect of visualizing arteries by peripheral venous injection.

Synchrotron Radiation And Its Application To Digital Subtraction Angiography

The intense synchrotron radiation produced by wiggler magnets at electron storage rings provides a new source of x-rays highly suited to iodine K-edge digital subtraction angiography. The monochromaticity and tunability provide maximum sensitivity to intraarterial iodine and virtually eliminate contrast due to soft tissue and bone. Visualization of arteries, in particular the coronary arteries, by peripheral venous injection is possible. A system design, based on tests already performed, is presented.

T. J. Krolicki

Papers

Synchrotron Radiation And Its Application To Digital Subtraction Angiography

Implementation of Digital Subtraction Angiography with a Synchrotron X-Ray Beam