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This is a study of the use of a dual-beam, dual-detector synchrotron radiation system for transvenous coronary angiography in a human subject. This system eliminates the need for rapid beam switching, increases X-ray fluence by a factor of about 2.5, and makes it possible to record high- and low-energy images simultaneously, thus excluding artifacts arising from time subtraction. Besides coronary angiography, it may be possible to image the vertebral-basilar arterial circulation with this system.

This study is related to an evaluation of synchrotron radiation for the non-invasive assessment of coronary artery disease in humans. In vivo canine studies are reported for an imaging system developed for use with synchrotron X-ray beams. The probable configuration of an expanded system for pilot human subject studies is described.

Imaging of coronary arteries using a venous instead of an arterial injection of contrast agent could provide a much safer method to diagnose heart disease. The tunability, intensity, and collimation of synchrotron radiation x‐ray beams makes possible imaging systems with greatly improved imaging sensitivity. A pair of fan x‐ray beams, a movable patient chair, and a multielement x‐ray detector are used to acquire a pair of x‐ray images above and below the iodine K edge. The logarithmic subtraction of these two images produces an image with excellent sensitivity to contrast agent and minimal sensitivity to bone and tissue. High‐quality images from a dog and preliminary images from five humans have been obtained. Improvements are being made to the system to increase the effective radiation flux and to measure the position of both x‐ray beams.

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.

X-ray-based angiography continues to be the standard method of assessing the severity and the extent of coronary atherosclerosis. The relative insensitivity of conventional X-ray imaging systems to iodine-containing contrast agents necessitates that the images be acquired with essentially undiluted contrast agent in the lumen of the vessels being studied. This, in turn, requires arterial catheterization and the insertion of the catheter tip in or near the ostia of the vessels and the direct injection of the contrast agent. The health risks and monetary costs of the procedure have limited its use to circumstances in which there is a high probability of the presence of severe disease. Despite these problems, coronary angiography has been employed in serial studies to evaluate the effects of drug therapy and diet on coronary atherosclerosis (1).

The intensity and tunability of synchrotron X-ray beams are highly suited to the non-invasive detection of iodine by K-edge digital subtraction angiography. An imnaging system developed for in vivo canine studies is described. Considerations relating to an expanded system for human subject studies are discussed.

During a series of experiments on crystal conduction counters performed at Stanford University on thallium halide crystals, we have observed motion of both hole and electron carriers in a TlBr crystal. At a temperature near -90 /sup 0/C the hole motion produces larger pulses than electron motion. We have studied the behavior of TlBr, TlCl, and KRS-5 (40 mol % TlBr + 60 mol % TlI) crystals and examined them as possible crystal conduction detectors of ..cap alpha.. particles and ..gamma.. rays. TlBr appears to be a promising candidate for applications to nuclear physics and high-energy ..gamma..-ray physics. Modules of TlBr in ''crystal-ball'' geometry may lead to new detection possibilities. At -20 /sup 0/C space-charge accumulation in TlBr decreases to such an extent that operation at this temperature seems possible with moderate electrical gradients. In the long-neglected field of crystal conduction counters, we have potentially removed the space-charge limitation in TlBr and, allowing for both hole and electron motion, raised the possibility for spectroscopic performance of this material for ..gamma..-ray studies.

The data acquisition system for the Crystal Ball project at SLAC is described. A PDP-11/t55 using RSX-11M connected to the SLAC Triplex is the basis of the system. A "physics pipeline" allows physicists to write their own equipment-monitoring or physics tasks which require event sampling. As well, an interactive analysis package (MULTI) is in the pipeline. Histogram collection and display on the PDP are implemented using the Triplex histogramming package. Various interactive event displays are also implemented.

The application of coronary angiography is limited because it requires arterial invasion and the direct injection of contrast agent into the coronary arteries. A prototype system has been developed which achieves sufficient sensitivity to the iodinated contrast agent to allow the visualization of coronary arteries in dogs after its intravenous injection. The system uses two fan beams of x-rays from an electron storage ring and a 300 element linear silicon detector. Two interlaced images, spaced at 150 eV above and below the K absorption edge of iodine (33.2 keV), are acquired and the logarithmic subtraction of these two images produces an image which has maximal sensitivity to iodine and minimal sensitivity to soft tissue and bone. This approach appears suitable for studies on human subjects.

Synchrotron radiation provides a new source of X-rays highly-suited to iodine K-edge Digital Subtraction Angiography (DSA). The use of such beams provides maximum sensitivity to intra-arterial iodine and virtually eliminates image contrast due to non-vascular body structures. The intensity of the beams permits short exposure times and allows images to be recorded, in line-scan fashion, in sharp focus despite arterial motions. The sensitivity of this method offers the prospect of visualizing arteries, and in particular the coronary arteries, by peripheral venous injection. The principles of DSA have been demonstrated using phantoms and excised animal hearts, and in vivo studies in animals have begun. The instrumentation developed for this purpose and the results obtained to date are summarized.

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.

Because coronary disease represents the principal health problem in the Western, industrialized world, and because of the risks and costs associated with conventional methods of visualizing the coronary arteries, an effort has been underway at the Stanford Synchrotron Radiation Laboratory to develop a less invasive coronary imaging procedure based on iodine K-edge dichromography. A pair of line images, recorded within a few milliseconds of each other, is taken with two monochromatic X-ray beams whose energy closely brackets the K-edge of iodine, 33.17 keV. The logarithmic subtraction of the images produced by these beams results in an image which greatly enhances signals arising from attenuation by iodine and almost totally suppresses signals arising from attenuation by soft tissue and bone. The high sensitivity to iodine allows the visualization of arterial structures after an intravenous injection of contrast agent and its subsequent 20-30 fold dilution. The experiments began in 1979, with initial studies done on phantoms and excised pig hearts. The first images of anesthetized dogs were taken in 1982. The results of experiments on dogs will be reviewed, showing the stepwise evolution of the imaging system, leading to the use of the system on human subjects in 1986. The images recorded on human subjects will be described and the remaining problems discussed.

A program is underway at the Stanford Synchrotron Radiation Laboratory to evaluate at minimally invasive method of visualizing the coronary arteries in man using synchrotron radiation. The design of an X-ray imaging system to accomodate a newly-available X-ray beam 12.3 cm in width is described. The system performance as revealed with test images of phantoms and excised hearts is indicated, and the system components to be tested before clinical studies can begin are identified.

The properties of detector arrays made up of NaI(Tl) Polyscin modules 20 in. deep and of hexagonal cross section and the development of a Monte Carlo code of general use in the design of such detectors are described. The use of modularized NaI(Tl) detectors in the study of a new spectroscopy of ?-rays in high energy physics is outlined.

Mechanical, or sound, vibrations were observed in ceramic piezoelectric disks of lead-zirconate-titanate (PZT) struck by high energy electrons. Four 1/2 inch thick disks of PZT were used. A wide band, low impedence, common base configuration amplifier was used to examine the induced vibrations. Since the most prominent resonant frequencies of the disks were near 40 kHz (radial mode) and 158 kHz (compressional mode) most of the studies were concentrated on these modes. Electrons of energy 1.00 BeV and 0.20 BeV were used in pulses, each lasting about 1.0 microsecond and contained 10,000 to 1,000,000 to electrons. The cross section of the incident 1.00 BeV beam was about 3 mm x 3 mm. (Author)

Scintillation crystals of CaI2 and CaI2(Eu) have been produced which iypically show pulse heights of 180% relative to NaI(Tl). The emission spectra for both pure and activated materials are well matched to a S-ll phototube response. Pure CaI2 has a decay time of 0.55, ?sec; CaI2(Eu) has a 0.79, ?sec decay time. Though this material is difficult to grow and to package, performance results thus far obtained are encouraging.

The aim was the development of an angiographic method and appropriate equipment for imaging with x-rays the coronary arteries in a non-invasive manner. Successive steps involved studies with phantoms, live animals and finally with human subjects. Clinical evaluation of human coronary arteries remains a goal of this and a continuing project, and steps along the way to such an achievement are in process. Transvenous injection of a dye using the method of iodine dichromography near 33.2 keV, the K-edge of iodine, forms the basis of the method. 11 refs.

A flexible method of detecting coincidences and short time intervals has been devised in which a photo‐multiplier tube views the screen of a cathode‐ray tube. By using one pulse as initiator of a sweep and the other in vertical presentation, coincidences can be observed in a fixed portion of the screen while the remainder of the screen is masked off. In present use the method is limited only by the pulses available (5×10−8 sec.). The method appears to be capable of extension to time intervals of the order of 9×10−10 second or smaller.