Compact monochromatic flash x-ray generator utilizing a disk-cathode molybdenum tube.

The high-voltage condensers in a polarity-inversion two-stage Marx surge generator are charged from -50 to -70 kV by a power supply, and the electric charges in the condensers are discharged to an x-ray tube after closing gap switches in the surge generator with a trigger device. The x-ray tube is a demountable diode, and the turbo molecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Clean molybdenum Kalpha lines are produced using a 20 microm-thick zirconium filter, since the tube utilizes a disk cathode and a rod target, and bremsstrahlung rays are not emitted in the opposite direction to that of electron acceleration. At a charging voltage of -70 kV, the instantaneous tube voltage and current were 120 kV and 1.0 kA, respectively. The x-ray pulse widths were approximately 70 ns, and the generator produced instantaneous number of Kalpha photons was approximately 3 x 10(7) photons/cm2 per pulse at 0.5 m from the source of 3.0 mm in diameter.

Demonstration of enhanced K-edge angiography using a cerium target x-ray generator.

The cerium target x-ray generator is useful in order to perform enhanced K-edge angiography using a cone beam because K-series characteristic x rays from the cerium target are absorbed effectively by iodine-based contrast mediums. The x-ray generator consists of a main controller, a unit with a Cockcroft-Walton circuit and a fixed anode x-ray tube, and a personal computer. The tube is a glass-enclosed diode with a cerium target and a 0.5-mm-thick beryllium window. The maximum tube voltage and current were 65 kV and 0.4 mA, respectively, and the focal-spot sizes were 1.0 x 1.3 mm. Cerium Kalpha lines were left using a barium sulfate filter, and the x-ray intensity was 0.48 microC/kg at 1.0 m from the source with a tube voltage of 60 kV, a current of 0.40 mA, and an exposure time of 1.0 s. Angiography was performed with a computed radiography system using iodine-based microspheres. In coronary angiography of nonliving animals, we observed fine blood vessels of approximately 100 microm with high contrasts.

Monochromatic polycapillary imaging utilizing a computed radiography system.

A fundamental study on quasi-parallel radiography using a polycapillary plate and a copper-target x-ray tube is described. In the experiments, the tube voltage was regulated from 12 to 22 kV, and the tube current was regulated within 3.0 mA by the filament temperature. The exposure time was controlled in order to obtain optimum x-ray intensity, and the maximum focal spot dimensions were approximately 2.0 x 1.5 mm. The thickness and the inner capillary tube diameter of the polycapillary were 1.0 mm and 25 microm, respectively. Monochromatic x-rays were produced using a 10 microm-thick nickel filter with a tube voltage of 17 kV, and these rays were formed into quasi-parallel beams by the polycapillary. The radiogram was taken using a computed radiography system utilizing imaging plates. In the measurement of image resolution, the spatial resolution hardly varied according to increases in the distance between the resolution-test chart and imaging plate using a polycapillary. A 50 microm tungsten wire could be observed, and fine blood vessels of approximately 100 microm were visible in angiography.

Irradiation of intense characteristic x-rays from weakly ionized linear molybdenum plasma.

In the plasma flash x-ray generator, a high-voltage main condenser of approximately 200 nF is charged up to 55 kV by a power supply, and electric charges in the condenser are discharged to an x-ray tube after triggering the cathode electrode. The flash x-rays are then produced. The x-ray tube is a demountable triode that is connected to a turbo molecular pump with a pressure of approximately 1 mPa. As electron flows from the cathode electrode are roughly converged to a rod molybdenum target of 2.0 mm in diameter by the electric field in the x-ray tube, weakly ionized linear plasma, which consists of molybdenum ions and electrons, forms by target evaporation. At a charging voltage of 55 kV, the maximum tube voltage was almost equal to the charging voltage of the main condenser, and the peak current was about 20 kA. When the charging voltage was increased, the linear plasma formed, and the K-series characteristic x-ray intensities increased. The K lines were quite sharp and intense, and hardly any bremsstrahlung rays were detected. The x-ray pulse widths were approximately 700 ns, and the time-integrated x-ray intensity had a value of approximately 35 micro C/kg at 1.0 m from the x-ray source with a charging voltage of 50 kV.