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Notes: We have developed a high resolution monochromatic x-ray computed tomography system using synchrotron radiation in the energy range up to 50 keV. The system was installed in a vertical wiggler beamline (BL14C) at the Photon Factory of the National Laboratory for High Energy Physics, and consists of a double-crystal monochromator employing asymmetric Bragg reflections, a photodiode array detector with a phosphor screen, and a microcomputer for control. Computed tomography (CT) images with a pixel size of 6 to 8 μm and with a slice width ranging from 20 to 100 μm were obtained. An image subtraction technique for CT images above and below the x-ray absorption edge of iodine was also evaluated for liquid-containing glass capillaries. Since the CT value (pixel weighting) is linearly proportional to the concentration, the system can quantitatively evaluate the concentration distribution of iodine. These results indicate that the system is very useful for nondestructively evaluating fine structures and their constituent elements.

Notes: The aim of this study is to visualize the coronary artery with the intravenus injection of contrast media. We propose a method of rapid and successive acquisition of two-dimensional images in a digital processing system which uses a pair of video cameras, a shutter operation, and a beam-splitting apparatus. A prototype of the high-speed acquisition system was constructed. The two-monochromatic video-camera method was very suitable for quick acquisition. Electro-optical shutters (PLZT) were found practical with respect to the dynamic range and response time. The field blanking method was essential for the data acquisition.

Notes: Coronary angiography by intravenous injection of contrast material using synchrotron radiation (SR) is a safe and easy method for diagnosis of coronary arteries. In Japan, a two-dimensional imaging system for coronary angiography is being developed. In that case, there exists a problem: Image contrast and visibility deteriorate due to harmful scattering x rays which are made when passing through a patient's body. Therefore, we have developed a simulation program in order to study the x-ray scattering behavior in a subject using monochromatic x rays and to find a method to decrease the scattering x rays in images using x-ray grids. The calculated results concerning the scattering x rays using the simulation program were compared with experimental results using monochromatic x rays at 33.17 keV from synchrotron radiation. © 1995 American Institute of Physics.

Notes: Ischemic heart disease is one of the most popular and lethal diseases for aged peoples in the world, and is usually diagnosed by transarterial selective coronary arteriography. However, it is rather invasive and somewhat dangerous, so that the selective coronary arteriography is not feasible for prospective screening of coronary occlusive heart disease. Conventional digital subtraction angiography (DSA) is widely known as a relatively noninvasive and useful technique is making a diagnosis of arterial occlusive disease, especially in making the diagnosis of ischemic heart disease. Conventional intravenous subtraction angiography by temporal subtraction, however, has several problems when applying to the moving objects. Digital subtraction method using high-speed switching above and below the K edge could be the ideal approach to this solution. We intend to make a synchrotron radiation digital K-edge subtraction angiography in the above policy, and to apply it to the human coronary ischemic disease on an outpatient basis. The principles and experimental systems have already been described in detail by our coworkers.Our prototype experimental system is situated at the AR (accumulation ring) for TRISTAN project of high energy physics. The available beam size is 70 mm by 120 mm. The electron energy of AR is 6.5 GeV and average beam current is approximately 10 mA. This paper will show the animal experiments of our K-edge subtraction system, and discuss some problems and technical difficulties. Three dogs, weighing approximately 15 kg, were examined to evaluate the ability of our prototype synchrotron radiation DSA unit, that we are now constructing. The dogs were anaesthetized with pentobarbital sodium, intravenously (30 mg/kg). Six french-sized (1.52 mm i.d.) pigtail catheter with multiple side holes were introduced via the right femoral vein into the right atrium by the cutdown technique under conventional x-ray fluoroscopic control. Respiration of the dogs was controlled by a mechanical ventilator. The respirations were held for several seconds when taking the images. Approximately 10 to 15 ml of 76% water soluble iodinated contrast medium (Urografin 76, Schering) was injected by an automatic electronic injector at the rate of approximately 10 ml/s. Three or four times injections were done so as not to exceed the normal renal excretion threshold.Intravenous drip infusion of saline (500 ml/2 h) was used to accelerate the washout of contrast medium via renal system. One hundred micrograms of nitroglycerin were administered, intravenously to dilate the coronary arteries, approximately 3 min prior to contrast injection. Sometimes we used 0.1 mg/kg of beta blockage agent (Propranorol) to decrease the heart rate. Subsequently, the heart rate of the dogs was decreased from approximately 200/s to 100/s. These techniques are commonly used in human examinations. Materials are positioned at left anterior oblique view. The sequential images are now detected above the iodine K edge by an image intensifier (RTP 9240F, Toshiba) and recorded at high signal-to-noise ratio analog video recording system (C1900, Hamamatsu Photonics, S/N 45 dB). Proximal coronary arteries are well visualized, however the distal portions are unsatisfactory, because of the overlapping of the contrast-filled dense heart chambers and pulmonary vessels. Bolus injection of contrast medium is also necessary, unless overlapping is inevitable, so are the same in conventional intravenous DSA. The energy above and below the K edge is now changed by tilting the angle of crystal, mechanically, so it has not sufficient speed to subtract the moving material. Real time A/D converter and frame buffering memories have not been available, until now. Even though there are many limitations in the hardware and many problems to overcome, our preliminary animal experiments allow us to have high expectations.

Notes: A fluorescent x-ray source for medical imaging, such as K-edge subtraction angiography and monochromatic x-ray CT, has been developed. Using a 6.5 GeV accumulation ring in Tsukuba, fluorescent x rays, which range from about 30 to 70 keV are generated by irradiating several target materials. Measurements have been made of output intensities and energy spectra for different target angles and extraction angles. The intensities of fluorescent x rays at a 30 mA beam current are on the order of 1–3×106 photons/mm2/s at 30 cm from the local spot where the incident beam is collimated to 1 mm2. A phantom which contains three different contrast media (iodine, barium, gadolinium) was used for the K-edge energy subtraction, and element selective CT images were obtained. © 1995 American Institute of Physics.

Notes: The first solid-state heterojunction device involving two conducting organic polymers has been fabricated from polyacetylene, (CH)x and p-doped poly(N-methylpyrrole), (PNP). Its electronic properties can be modified by chemically partly reducing or partly oxidizing the PNP. The junction has been characterized by J-V studies and by preliminary photovoltaic measurements.