Hidezo Mori

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.

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.

Clean monochromatic x-ray irradiation from weakly ionized linear copper plasma

In the plasma flash x-ray generator, a 200-nF condenser is charged up to 50 kV by a power supply, and flash x-rays are produced by the discharging. The x-ray tube is a demountable triode with a trigger electrode, and the turbomolecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Target evaporation leads to the for- mation of weakly ionized linear plasma, consisting of copper ions and electrons, around the fine target, and intense Ka rays are produced us- ing a 10-mm-thick nickel filter. At a charging voltage of 50 kV, the maxi- mum tube voltage is almost equal to the charging voltage of the main condenser, and the peak current is about 15 kA. When the charging voltage is increased, the linear plasma forms, and the copper Ka inten- sities substantially increase. The Ka lines are quite clean and intense, and hardly any bremsstrahlung rays are detected at all. The x-ray pulse widths are approximately 700 ns, and the time-integrated x-ray intensity has a value of approximately 20 mC/kg at 1.0 m from the x-ray source with a charging voltage of 50 kV.

High-speed enhanced K-edge angiography utilizing cerium plasma x-ray generator

The cerium target plasma flash x-ray generator is useful to perform high-speed enhanced K-edge angiography using cone beams, because K-series characteristic x-rays from the cerium target are absorbed effectively by iodine-based contrast mediums. In the plasma generator, a 200-nF condenser is charged up to 60 kV by a power supply, and flash x-rays are produced by the discharging. The x-ray tube is a demountable triode with a trigger electrode, and the turbomolecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Target evaporation leads to the formation of weakly ionized linear plasma, consisting of cerium ions and electrons, around the target, and intense flash x-rays are produced. At a charging voltage of 55 kV, the maximum tube voltage is almost equal to the charging voltage of the main condenser, and the maximum current is approximately 20 kA. When the charging voltage is increased, weakly ionized cerium plasma forms, and the K-series characteristic x-ray intensities increase. The x-ray pulse widths are about 500 ns, and the time-integrated x-ray intensity has a value of about 40 µC/kg at 1.0 m from the x-ray source with a charging voltage of 55 kV. In the angiography, we employ a filmless computed radiography (CR) system and iodine-based microspheres.

Quasi-Monochromatic X-Ray Generator Utilizing Graphite Cathode Diode with Transmission-Type Molybdenum Target

An X-ray generator consists of a negative high-voltage power supply and a field-emission-type cold-cathode X-ray tube. The tube is a glass-enclosed diode utilizing a transmission-type molybdenum target with a thickness of 20 µm, a needle graphite (carbon) cathode, a glass tube body, and a 0.5-mm-thick beryllium window. The tube current decreases gradually with time. After aging for 30 minutes, the tube current was approximately 0.2 mA with a tube voltage of 25 kV, and the focal-spot dimensions were 2.2×1.6 mm. Characteristic X-rays of molybdenum K-series were obtained after penetrating the molybdenum target and the beryllium window, and the K-absorption edge was observed clearly. The generator produced number of K photons was approximately 4×106 photons/cm2s at 1.0 m from the source. The average photon energies of Kα and Kβ lines were 17.4 and 19.6 keV, respectively, and quasi-monochromatic radiography was performed using a computed radiography system.

Preliminary study for producing higher harmonic hard x-rays from weakly ionized copper plasma

In the plasma flash x-ray generator, a 200 nF condenser is charged up to 50 kV by a power supply, and flash x-rays are produced by the discharging. The x-ray tube is a demountable triode with a trigger electrode, and the turbomolecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Target evaporation leads to the formation of weakly ionized linear plasma, consisting of copper ions and electrons, around the fine target, and intense Kα lines are left using a 10-μm-thick nickel filter. At a charging voltage of 50 kV, the maximum tube voltage was almost equal to the charging voltage of the main condenser, and the peak current was about 16 kA. The K-series characteristic x-rays were clean and intense, and higher harmonic x-rays were observed. The x-ray pulse widths were approximately 300 ns, and the time-integrated x-ray intensity had a value of approximately 1.5 mGy per pulse at 1.0 m from the x-ray source with a charging voltage of 50 kV.

Demonstration of flash K-edge angiography utilizing gadolinium-based contrast medium

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 turbomolecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Tungsten characteristic x rays can be produced, 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 140 kV and 1.0 kA, respectively. The x-ray pulse widths were approximately 90 ns, and the estimated number of K photons was approximately 5×108 photons/cm2 per pulse at 0.5 m from the source of 3.0 mm in diameter.

Superposition of x-ray spectra using double-target plasma triode

In the plasma flash x-ray generator, a 200 nF condenser is charged up to 50 kV by a power supply, and flash x rays are produced by the discharging. The x-ray tube is a demountable triode with a double target consisting of a copper and a molybdenum rods, and the turbomolecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Target evaporation leads to the formation of weakly ionized linear plasma, consisting of metal ions and electrons, around the fine target, and intense characteristic x rays are produced. At a charging voltage of 50 kV, the maximum tube voltage was almost equal to the charging voltage of the main condenser, and the peak current was about 11 kA. When the charging voltage was increased, the linear plasma formed, and the molybdenum K-series characteristic x-ray intensities increased substantially. Although the intensities of copper Kα lines increased with increases in the charging voltage, hardly any clean Kα lines were detected. The x-ray pulse widths were approximately 1.2 μs, and the time-integrated x-ray intensity was approximately 30 μC/kg at 1.0 m from the x-ray source with a charging voltage of 50 kV.

Intense quasi-monochromatic flash x-ray generator utilizing molybdenum-target diode

In the flash x-ray generator, a 150 nF condenser is charged up to 80 kV by a power supply, and flash x rays are produced by the discharging. The x-ray tube is a demountable diode, and the turbomolecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Since the electric circuit of the high-voltage pulse generator employs a cable transmission line, the high-voltage pulse generator produces twice the potential of the condenser charging voltage. At a charging voltage of 80 kV, the estimated maximum tube voltage and current were approximately 160 kV and 40 kA, respectively. When the charging voltage was increased, the K-series characteristic x-ray intensities of molybdenum increased. The K lines were clean and intense, and hardly any bremsstrahlung rays were detected at all. The x-ray pulse widths were approximately 100 ns, and the time-integrated x-ray intensity had a value of approximately 15 μC/kg at 1.0 m from the x-ray source with a charging voltage of 80 kV.

Monochromatic flash x-ray generator utilizing disk-cathode silver 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 turbomolecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Clean silver Kα lines are produced using a 30 μm-thick palladium 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 90 kV and 0.8 kA, respectively. The x-ray pulse widths were approximately 80 ns, and the instantaneous number of generator-produced Kα photons was approximately 40 M photons/cm2 per pulse at 0.3 m from the source of 3.0 mm in diameter.