X-ray photons are detected using an Lu2(SiO4)O [LSO] single-crystal scintillator with a decay time of 40 ns and a multipixel photon counter (MPPC). The photocurrent from the MPPC is amplified by a high-speed current-voltage
amplifier with an 80 MHz-gain-band operational amplifier, and the 200-ns-width event pulses are sent to a multichannel
analyzer to measure X-ray spectra. The MPPC is driven in the pre-Geiger mode at a bias voltage of 70.7 V and a
temperature of 23°C. Photon-counting computed tomography (PC-CT) is accomplished by repeated linear scans and
rotations of an object, and projection curves of the object are obtained by linear scanning. The exposure time for
obtaining a tomogram was 10 min with scan steps of 0.5 mm and rotation steps of 1.0°. At a tube voltage of 100 kV, the
maximum count rate was 350 kcps/pixel. We carried out PC-CT using gadolinium media and confirmed the energydispersive
effect with changes in the lower level voltage of event pulses using a comparator.
X-ray photon counting was performed using a readymade silicon-PIN photodiode (Si-PIN-PD) at tube voltages ranging
from 42 to 60 kV, and X-ray photons are directly detected using the 100 MHz Si-PIN-PD without a scintillator.
Photocurrent from the diode is amplified using charge-sensitive and shaping amplifiers. Using a multichannel analyzer,
X-ray spectra at a tube voltage of 60 kV could easily be measured. The photon-counting computed tomography (PCCT)
is accomplished by repeated linear scans and rotations of an object, and projection curves of the object are obtained
by the linear scan. In the PC-CT, we confirmed the energy-dispersive effect with changes in lower-level voltage of the
event pulse using a comparator.
X-ray photon counting was performed using a silicon X-ray diode (Si-XD) at a tube current of 2.0 mA and tube voltages
ranging from 50 to 70 kV. The Si-XD is a high-sensitivity Si photodiode selected for detecting X-ray photons, and Xray
photons are directly detected using the Si-XD without a scintillator. Photocurrent from the diode is amplified using
charge-sensitive and shaping amplifiers. To investigate the X-ray-electric conversion, we performed the event-pulseheight
(EPH) analysis using a multichannel analyzer. Photon-counting computed tomography (PC-CT) is accomplished
by repeated linear scans and rotations of an object, and projection curves of the object are obtained by the linear scan.
The exposure time for obtaining a tomogram was 10 min at a scan step of 0.5 mm and a rotation step of 1.0°. In PC-CT
at a tube voltage of 70 kV, the image contrast of iodine media fell with increasing lower-level voltage of the event pulse
using a comparator.
A high-sensitive X-ray computed tomography (CT) system is useful for decreasing absorbed dose for patients, and a
dark-count-less photon-counting CT system was developed. X-ray photons are detected using a YAP(Ce) [cerium-doped
yttrium aluminum perovskite] single crystal scintillator and an MPPC (multipixel photon counter). Photocurrents are
amplified by a high-speed current-voltage amplifier, and smooth event pulses from an integrator are sent to a high-speed comparator. Then, logical pulses are produced from the comparator and are counted by a counter card. Tomography is accomplished by repeated linear scans and rotations of an object, and projection curves of the object are obtained by the linear scan. The image contrast of gadolinium medium slightly fell with increase in lower-level voltage (Vl) of the comparator. The dark count rate was 0 cps, and the count rate for the CT was approximately 250 kcps.
A low-dose-rate X-ray computed tomography (CT) system is useful for reducing absorbed dose for patients. The CT
system with a tube current of 1.91 mA was developed using a silicon-PIN X-ray diode (Si-PIN-XD). The Si-PIN-XD is
a selected high-sensitive Si-PIN photodiode (PD) for detecting X-ray photons. X-ray photons are detected directly using
the Si-PIN-XD without a scintillator, and the photocurrent from the diode is amplified using current-voltage and
voltage-voltage amplifiers. The output voltage is converted into logical pulses using a voltage-frequency converter with maximum frequency of 500 kHz, and the frequency is proportional to the voltage. The pulses from the converter are sent to differentiator with a time constant of 1 μs to generate short positive pulses for counting, and the pulses are counted using a counter card. Tomography is accomplished by repeated linear scans and rotations of an object, and projection curves of the object are obtained by the linear scan. The exposure time for obtaining a tomogram was 5 min at a scan step of 0.5 mm and a rotation step of 3.0°. The tube current and voltage were 1.91 mA and 100 kV, respectively, and gadolinium K-edge CT was carried out using filtered X-ray spectra with a peak energy of 52 keV.
X-ray fluorescence (XRF) analysis is useful for mapping various atoms in objects. Bremsstrahlung X-rays are selected
using a 3.0 mm-thick aluminum filter, and these rays are absorbed by indium, cerium and gadolinium atoms in objects.
Then XRF is produced from the objects, and photons are detected by a cadmium-telluride detector. The Kα photons are
discriminated using a multichannel analyzer, and the number of photons is counted by a counter card. The objects are
moved and scanned by an x-y stage in conjunction with a two-stage controller, and X-ray images obtained by atomic
mapping are shown on a personal computer monitor. The scan steps of the x and y axes were both 2.5 mm, and the
photon-counting time per mapping point was 0.5 s. We carried out atomic mapping using the X-ray camera, and Kα photons from cerium and gadolinium atoms were produced from cancerous regions in nude mice.
10 Mcps photon counting was carried out using a detector consisting of a 2.0 mm-thick ZnO (zinc oxide) single-crystal
scintillator and an MPPC (multipixel photon counter) module in an X-ray computed tomography (CT) system. The
maximum count rate was 10 Mcps (mega counts per second) at a tube voltage of 70 kV and a tube current of 2.0 mA.
Next, a photon-counting X-ray CT system consists of an X-ray generator, a turntable, a scan stage, a two-stage
controller, the ZnO-MPPC detector, a counter card (CC), and a personal computer (PC). Tomography is accomplished
by repeated linear scans and rotations of an object, and projection curves of the object are obtained by the linear scan
with a scan velocity of 25 mm/s. The pulses of the event signal from the module are counted by the CC in conjunction
with the PC. The exposure time for obtaining a tomogram was 600 s at a scan step of 0.5 mm and a rotation step of 1.0°,
and photon-counting CT was accomplished using iodine-based contrast media.
We developed an embossed radiography system utilizing single- and dual-energy subtractions for decreasing the
absorption contrast of unnecessary regions, and contrast resolution of a target region was increased using image-shifting
subtraction and a linear-contrast system in a flat panel detector (FPD). To carry out embossed radiography, we
developed a computer program for two-dimensional subtraction, and a conventional x-ray generator with a 0.5-mm-focus tube was used. Energy subtraction was performed at tube voltages of 42.5 and 70.0 kV, a tube current of 1.0 mA, and an x-ray exposure time of 5.0 s. Embossed radiography was achieved with cohesion imaging by use of the
FPD with pixel sizes of 48 ×48 μm, and the shifting dimension of an object in the horizontal and vertical directions
ranged from 48 to 144 μm. We obtained high-contrast embossed images of fine bones and coronary arteries approximately 100 μm in diameter.
An energy-discrimination K-edge x-ray computed tomography (CT) system is useful for controlling the image contrast of a target region by selecting both the photon energy and the energy width. The CT system has an oscillation-type linear cadmium telluride (CdTe) detectror. CT is performed by repeated linear scans and rotations of an object. Penetrating x-ray photons from the object are detected by a CdTe detector, and event signals of x-ray photons are produced using charge-sensitive and shaping amplifiers. Both photon energy and energy width are selected out using a multichannel analyzer, and the number of photons is counted by a counter card. In energy-discrimination CT, the tube voltage and tube current were 80 kV and 20 μA, respectively, and the x-ray intensity was 1.92 μGy/s at a distance of 1.0 m from the source and a tube voltage of 80 kV. The energy-discrimination CT was carried out by selecting x-ray photon energies.
An energy-discriminating x-ray camera is useful for performing monochromatic radiography using polychromatic x rays. This x-ray camera was developed to carry out K-edge radiography using iodine-based contrast media. In this camera, objects are exposed by a cone beam from a cerium x-ray generator, and penetrating x-ray photons are detected by a cadmium telluride detector with an amplifier unit. The optimal x-ray photon energy and the energy width are selected out using a multichannel analyzer, and the photon number is counted by a counter card. Radiography was performed by the detector scanning using an x-y stage driven by a two-stage controller, and radiograms obtained by energy discriminating are shown on a personal computer monitor. In radiography, the tube voltage and current were 60 kV and 36 µA, respectively, and the x-ray intensity was 4.7 µGy/s. Cerium K-series characteristic x rays are absorbed effectively by iodine-based contrast media, and iodine K-edge radiography was performed using x rays with energies just beyond iodine K-edge energy 33.2 keV.
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 ferrum ions and electrons, around the fine target, and intense K-series
characteristic x-rays are produced from the plasma axial direction. 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 15 kA. In the
spectral measurement, Kβ rays were intense, and higher harmonic x-rays were observed. The pulse widths were 0.5 μs,
and the maximum x-ray intensity was approximately 300 μGy.
A high-speed x-ray tomography system is useful for observing high-speed phenomena. The experimental setup for
tomography consists of a tungsten-target x-ray generator, a tungsten collimator, and a computed radiography system.
An object was exposed by a 2-mm-thick fun beam from the x-ray generator, and scattering x-rays from the slice plane
were detected using an imaging plate through a tungsten collimator with hole diameters of 0.8 mm. Because the
exposed dose for tomography was almost equal to those obtained using two intense flash x-ray generators,
ultra-high-speed tomography could be performed.
Embossed radiography is an important technique for imaging target region by decreasing absorption contrast of objects. The ultra-high-speed embossed radiography system consists of a computed radiography system, an intense flash x-ray generator, and a computer program for shifting the image pixel. In the flash x-ray generator, a high-voltage condenser of 200 nF was charged to 50 kV, and the electric charges in the condenser were discharged to the flash x-ray tube after triggering the cathode electrode. The molybdenum-target evaporation lead to the formation of weakly ionized linear plasma, and intense molybdenum K-series x-rays were produced. High-speed radiography was performed using molybdenum K-rays, and the embossed radiography was carried out utilizing single-energy subtraction after the image shifting. The minimum spatial resolution was equal to the sampling pitch of the CR system of 87.5 μm, and concavoconvex radiography such as phase-differential imaging was performed with an x-ray duration of approximately 0.5 Μs.
Characteristic x-ray generator consists of a constant high-voltage power supply, a filament power supply, a
turbomolecular pump, and an x-ray tube. The x-ray tube is a demountable diode which is connected to the
turbomolecular pump and consists of the following major devices: a pipe-shaped molybdenum hole target, a tungsten
hairpin cathode (filament), a focusing (Wehnelt) electrode, a polyethylene terephthalate x-ray window 0.25 mm in
thickness, and a stainless-steel tube body. In the x-ray tube, the positive high voltage is applied to the anode (target)
electrode, and the cathode is connected to the tube body (ground potential). In this experiment, the tube voltage applied
was from 25 to 35 kV, and the tube current was regulated to within 10 μA by the filament temperature. The exposure
time is controlled in order to obtain optimum x-ray intensity. The electron beams from the cathode are converged to the
target by the focusing electrode, and sharp K-series characteristic x-rays are produced through the focusing electrode at
a tube voltage of 35 kV. Using this generator, we performed monochromatic radiography, monochromatic x-ray
computed tomography, and x-ray fluorescence analysis.
Energy-discriminating x-ray camera is useful for performing monochromatic radiography using polychromatic x-rays.
The x-ray camera was developed to carry out K-edge radiography using iodine-based contrast media. In this camera,
objects are exposed by a cerium x-ray generator, and penetrating x-rays are detected by a cadmium telluride (CdTe)
detector with an amplifier unit. The optimal x-ray photon energy and energy width are selected out using a multichannel
analyzer (MCA), and the photon number is counted by a counter board (CB). Radiography was performed by the
detector scanning using an x-y stage driven by a two-stage controller, and x-ray images obtained by energy
discriminating are shown in a personal-computer (PC) monitor. Cerium K-series characteristic x-rays are absorbed
effectively by iodine based contrast media, and iodine K-edge radiography was performed using x-rays with photon
energies just beyond K-edge energy 33.2 keV.
A photon-counting K-edge x-ray Computed Tomography (CT) system is useful for discriminating photon energy and for
decreasing absorbed dose for patients. The CT system is of the first generation type and consists of an x-ray generator, a
turn table, a translation stage, a two-stage controller, a multipixel photon counter (MPPC) module, a 0.5-mm-thick
zinc oxide (ZnO) scintillator, a counter board (CB), and a personal computer (PC). Tomography is accomplished by
repeating the translation and rotation of an object. Penetrating x-ray photons from the object are detected by the
scintillator in conjunction with the MPPC module, and the event signals are counted by the CB. Without using energy
discriminating, photon counting CT was carried out by controlling x-ray spectra.
Digital subtraction is useful for carrying out embossed radiography by shifting an x-ray source, and energy subtraction
is an important technique for imaging target region by deleting unnecessary region in vivo. X-ray generator had a
100-μm-focus tube, energy subtraction was performed at tube voltages of 40 and 60 kV, and a 3.0-mm-thick aluminum
filter was used to absorb low-photon-energy bremsstrahlung x-rays. Embossed radiography was achieved with cohesion
imaging using a flat panel detector (FPD) with pixel sizes of 48×48 μm, and the shifting distance of the x-ray source in
horizontal direction and the distance between the x-ray source and the FPD face were 5.0 mm and 1.0 m, respectively.
At a tube voltage of 60 kV and a tube current of 0.50 mA, x-ray intensities without filtering and with filtering were 307
and 28.4 μGy/s, respectively, at 1.0 m from the source. In embossed radiography of non-living animals, the spatial
resolution measured using a lead test chart was approximately 70 μm, and we observed embossed images of fine bones,
soft tissues, and coronary arteries of approximately 100 μm.
X-Ray Fluorescence (XRF) analysis is useful for measuring density distributions of contrast media in vivo. An XRF
camera was developed to carry out mapping for iodine-based contrast media used in medical angiography. In this
camera, objects are exposed by an x-ray beam formed using a 3.0-mm-diameter lead hole. Next, cerium K-series
characteristic x-rays are absorbed effectively by iodine media in objects, and iodine fluorescences are produced from
the objects. Iodine Kα fluorescences are selected out using a 58-μm-thick stannum filter and are detected by a cadmium
telluride (CdTe) detector. Kα rays are discriminated out by a multichannel analyzer (MCA), and photon number is
counted by a counter board (CB). The objects are moved and scanned using an x-y stage driven by a two-stage
controller, and x-ray images obtained by iodine mapping are shown in a personal computer (PC) monitor. In particular,
iodine fluorescences were produced from remanent iodine elements in a cancer region of a rabbit ear.
An x-ray fluorescence (XRF) computed tomography (CT) system utilizing a cadmium telluride (CdTe) detector is
described. The CT system is of the first generation type and consists of a cerium x-ray generator, a turn table, a
translation stage, a two-stage controller, a CdTe spectrometer, a multichannel analyzer (MCA), a counter board (CB),
and a personal computer (PC). When an object is exposed by the x-ray generator, iodine K-series fluorescences are
produced and are detected from vertical direction to x-ray axis using the spectrometer. Fluorescent photons are selected
out using the MCA and are counted by the PC via CB, and XRF CT is performed by repeating translation and rotation
of an object.
An energy-discriminating K-edge x-ray Computed Tomography (CT) system is useful for increasing contrast resolution
of a target region and for diagnosing cancers utilizing a drug delivery system. The CT system is of the first generation
type and consists of an x-ray generator, a turn table, a translation stage, a two-stage controller, a cadmium telluride
(CdTe) detector, a charge amplifier, a shaping amplifier, a multi-channel analyzer (MCA), a counter board (CB), and a
personal computer (PC). The K-edge CT is accomplished by repeating translation and rotation of an object. Penetrating
x-ray spectra from the object are measured by a spectrometer utilizing the CdTe detector, amplifiers, and MCA. Both
the photon energy and the energy width are selected by the MCA for discriminating photon energy. Enhanced iodine
K-edge x-ray CT was performed by selecting photons with energies just beyond iodine K-edge energy of 33.2 keV.
A fluorescent x-ray tomography system is useful in performing fluorescent x-ray analysis for target atoms in
biomedical objects utilizing a drug deliverly system. This tomography system is employed in order to measure iodine
distribution in objects, and the system consists of a cerium x-ray generator, a 58-μm-thick stannum filter, a tungsten
collimator, and a computed radiography system. Because K-series characteristic x-rays from the cerium target are
absorbed effectively by iodine-based contrast media, iodine fluorescent x-rays from iodine atoms in the objects are
produced. In the tomography system, when the objects are exposed by fan beams, the stannum filter easily transmits
iodine Kα rays from a slice plane, and tomograms are obtained using the CR system and the collimator.
A simple x-ray computed tomography (CT) system utilizing a cadmium telluride detector and its application to
enhanced iodine K-edge angiography are described. The CT system is of the first generation type and consists of an
x-ray generator, a turn table, a translation unit, a motor drive unit, a cadmium telluride detector, an interface unit for
the detector, and a personal computer (PC). Tomography was performed by the repetition of the translation and
rotation. Narrow-photon-energy bremsstrahlung x-rays with a peak photon energy of approximately 35 keV is very
useful for performing enhanced K-edge angiography because these rays are absorbed effectively by iodine-based
contrast media with a K-edge of 33.2 keV. The tube voltage, the tube current, and the aluminum filter thickness were
60 kV, 1.5 mA, and 3.0 mm, respectively. Holes filled with iodine media in phantoms are visible with high contrasts,
and the CT system can be applied to photon-counting and fluorescent x-ray CT systems.
Detection of high-dose-rate pulse x-rays from a samarium plasma flash x-ray generator utilizing a multipixel photon
counter is described. Monochromatic K-series characteristic x-rays are detected by a plastic scintillator, and
fluorescent lights are lead to the photon counter through a 10-m-length plastic fiber. The reverse bias was 70.0 V, and
x-ray outputs were recorded by a digital storage scope. The samarium plasma flash x-ray generator is useful for
performing high-speed enhanced K-edge angiography using cone beams because K-series characteristic x-rays from
the samarium target are absorbed effectively by iodine-based contrast media. 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. 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 are approximately 160 kV and 40 kA, respectively. When the charging voltage was
increased, the K-series characteristic x-ray intensities of samarium increased. Bremsstrahlung x-ray intensity rate
decreased with increasing the charging voltage, and K lines were produced with a charging voltage of 80 kV. The
x-ray pulse widths were approximately 100 ns, and the time-integrated x-ray intensity had a value of approximately
500 μGy at 1.0 m from the x-ray source with a charging voltage of 80 kV. Angiography was performed using a
filmless computed radiography (CR) system and iodine-based contrast media. In the angiography of nonliving animals,
we observed fine blood vessels of approximately 100 μm with high contrasts.
A preliminary experiment for producing narrow-photon-energy cone-beam x-rays using a silicon single crystal is
described. In order to produce low-photon-energy x-rays, a 100-µm-focus x-ray generator in conjunction with a (111)
plane silicon crystal is employed. The x-ray beams from the source are confined by an x-y diaphragm, and
monochromatic cone beams are formed by the crystal and three lead plates. The x-ray generator consists of a main
controller and a unit with a high-voltage circuit and a 100-µm-focus x-ray tube. In this experiment, the maximum tube
voltage and current were 35 kV and 0.50 mA, respectively, and the x-ray intensity of the microfocus generator was
343 μGy/s at 1.0 m from the source with a tube voltage of 30 kV and a current of 0.50 mA. The effective photon
energy is determined by Bragg's angle, and the photon-energy width is regulated by the angle delta. Using this
generator in conjunction with a computed radiography system, quasi-monochromatic radiography was performed
using a cone beam with an effective energy of approximately 15.5 keV.
In a 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 discharge. 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. Because bremsstrahlung rays are not emitted in the opposite direction of that of electron trajectory, clean molybdenum K-series characteristic x-rays can be produced without using a filter. When the charging voltage is increased, the K-series characteristic x-ray intensities of molybdenum increase. The K lines are clean and intense, and hardly any bremsstrahlung rays are detected. The x-ray pulse widths are approximately 100 ns, and the time-integrated x-ray intensity has a value of approximately 500 µGy per pulse at 1.0 m from the x-ray source, with a charging voltage of 80 kV.
High-sensitive radiography system utilizing a kilohertz-range stroboscopic x-ray generator and a night-vision CCD
camera (MLX) is described. The x-ray generator consists of the following major components: a main controller, a
condenser unit with a Cockcroft-Walton circuit, and an x-ray tube unit in conjunction with a grid controller. The main
condenser of about 500 nF in the unit is charged up to 100 kV by the circuit, and the electric charges in the condenser
are discharged to the triode by the grid control circuit. The maximum tube current and the repetition rate are
approximately 0.5 A and 50 kHz, respectively. The x-ray pulse width ranges from 0.01 to 1.0 ms, and the maximum
shot number has a value of 32. At a charging voltage of 60 kV and a width of 1.0 ms, the x-ray intensity obtained
without filtering was 6.04 μGy at 1.0 m per pulse. In radiography, an object is exposed by the pulse x-ray generator,
and a radiogram is taken by an image intensifier. The image is intensified by the CCD camera, and a stop-motion
image is stored by a flash memory device using a trigger delay device. The image quality was improved with increases
in the x-ray duration, and a single-shot radiography was performed with durations of less than 1.0 ms.
The gadolinium plasma flash x-ray generator is useful for performing high-speed enhanced K-edge angiography using
cone beams because K-series characteristic x-rays from the gadolinium target are absorbed effectively by iodine-based
contrast media. 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 cold-cathode 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 are
approximately 160 kV and 40 kA, respectively. When the charging voltage was increased, the K-series characteristic
x-ray intensities of gadolinium increased. Bremsstrahlung x-ray intensity rate decreased with increasing the charging
voltage, and clean K lines were produced with a charging voltage of 80 kV. The x-ray pulse widths were
approximately 100 ns, and the time-integrated x-ray intensity had a value of approximately 500 μGy at 1.0 m from the
x-ray source with a charging voltage of 80 kV. Angiography was performed using a filmless computed radiography
(CR) system and iodine-based contrast media. In the angiography of nonliving animals, we observed fine blood
vessels of approximately 100 μm with high contrasts.
Novel monochromatic x-ray generators and their applications to high-speed radiography are described. The five
generators are as follows: a weakly ionized linear plasma x-ray generator, a monochromatic compact flash x-ray
generator, a super-fluorescent plasma generator, a cerium x-ray generator using a 3.0-mm-thick aluminum filter, and a
100micron-focus x-ray generator utilizing the filter. Using the linear plasma generator with a copper target, we observed
clean K lines and their harmonics, and soft flash radiography was performed with pulse widths of approximately 500
ns. The compact monochromatic flash x-ray generator produced clean molybdenum K lines easily, and high-speed
radiography was performed with pulse widths of approximately 100 ns. Using a steady-state cerium x-ray generator,
we performed real-time angiography utilizing an image intensifier and a high-sensitive camera (MLX) made by NAC
Image Technology Inc. with a capture time of 1 ms. Finally, real-time magnification radiography was performed by
twofold magnification imaging using a 100micron-focus x-ray generator and the high-sensitive camera.
This generator consists of the following components: a constant high-voltage power supply, a filament power supply, a turbomolecular pump, and an x-ray tube. The x-ray tube is a demountable diode which is connected to the turbomolecular pump and consists of the following major devices: a tungsten hairpin cathode (filament), a focusing (Wehnelt) electrode, a polyethylene terephthalate x-ray window 0.25 mm in thickness, a stainless-steel tube body, a pipe target, and a rod target. The pipe and rod targets are useful for forming linear and cone beams, respectively. In the x-ray tube, the positive high voltage is applied to the anode (target) electrode, and the cathode is connected to the tube body (ground potential). In this experiment, the tube voltage applied was from12 to 20 kV, and the tube current was regulated to within 0.10 mA by the filament temperature. The exposure time is controlled in order to obtain optimum x-ray intensity. The electron beams from the cathode are converged to the target by the focusing electrode, and clean K-series characteristic x-rays are produced through the focusing electrode without using a filter. The x-ray intensities of the pipe and rod targets were 1.29 and 4.28 μGy/s at 1.0 m from the x-ray source with a tube voltage of 15 kV and a tube current of 0.10 mA, and quasi-monochromatic radiography was performed using a computed radiography system.
A microfocus x-ray tube is useful in order to perform magnification digital radiography including phase-contrast effect.
The 100-µm-focus x-ray generator consists of a main controller for regulating the tube voltage and current and a tube
unit, with a high-voltage circuit and a fixed anode x-ray tube. The maximum tube voltage, current, and electric power
were 105 kV, 0.5 mA, and 50 W, respectively. Using a 3.0-mm-thick aluminum filter, the x-ray intensity was 26.0
µGy/s at 1.0 m from the source with a tube voltage of 60 kV and a current of 0.50 mA. Because the peak photon
energy was approximately 35 keV using the filter with a tube voltage of 60 kV, the bremsstrahlung x-rays were
absorbed effectively by iodine-based contrast media with an iodine K-edge of 33.2 keV. Real-time magnification
radiography was performed by twofold magnification imaging with an image intensifier camera, and angiography was
achieved with iodine-based microspheres 15 µm in diameter. In angiography of non-living animals, we observed fine
blood vessels of approximately 100 µm with high contrasts.
The samarium-target x-ray tube is useful in order to perform cone-beam K-edge angiography because K-series
characteristic x-rays from the samarium target are absorbed effectively by iodine-based contrast media. This generator
consists of the following components: a constant high-voltage power supply, a filament power supply, a
turbomolecular pump, and an x-ray tube. The x-ray tube is a demountable diode which is connected to the
turbomolecular pump and consists of the following major devices: a samarium target, a tungsten hairpin cathode
(filament), a focusing (Wehnelt) electrode, a polyethylene terephthalate x-ray window 0.25 mm in thickness, and a
stainless-steel tube body. In the x-ray tube, the positive high voltage is applied to the anode (target) electrode, and the
cathode is connected to the tube body (ground potential). In this experiment, the tube voltage applied was from 50 to
70 kV, and the tube current was regulated to within 0.10 mA by the filament temperature. The exposure time is
controlled in order to obtain optimum x-ray intensity. The electron beams from the cathode are converged to the target
by the focusing electrode, and bremsstrahlung x-rays were absorbed using a 50-µm-thick tungsten filter. The x-ray
intensity was 1.04 μGy/s at 1.0 m from the x-ray source with a tube voltage of 60 kV and a tube current of 0.10 mA,
and angiography was performed using a computed radiography system and iodine-based microspheres 15 µm in
diameter. In angiography of non-living animals, we observed fine blood vessels of approximately 100 µm with high
contrasts.
Energy-selective high-speed radiography utilizing a kilohertz-range stroboscopic x-ray generator and its application to high-speed angiography are described. This generator consists of the following major components: a main controller, a condenser unit with a Cockcroft-Walton circuit, and an x-ray tube unit in conjunction with a grid controller. The main condenser of about 500 nF in the unit is charged up to 120 kV by the circuit, and the electric charges in the condenser are discharged to the triode by the grid control circuit. Although the tube voltage decreased during the discharging for generating x-rays, the maximum value was equal to the initial charging voltage of the main condenser. The maximum tube current and the repetition rate were approximately 0.5 A and 50 kHz, respectively. The x-ray pulse width ranged from 0.01 to 1.0 ms, and the maximum shot number had a value of 32. At a charging voltage of 100 kV and a width of 1.0 ms, the x-ray intensity obtained using a 50-μm-thick tungsten filter was 9.88 μGy at 1.0 m, and the dimensions of the focal spot had values of approximately 1×1 mm. Angiography was performed using the filter at a charging voltage of 100 kV.
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.
The tungsten plasma flash x-ray generator is useful in order to perform high-speed enhanced K-edge angiography using cone beams because Kα rays from the tungsten target are absorbed effectively by gadolinium-based contrast media. 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 characteristic x-ray intensities of tungsten Kα lines increased. Using an ytterbium oxide filter, the Kα lines were clean, and hardly any Kβ lines and bremsstrahlung rays were detected. The x-ray pulse widths were approximately 60 ns, and the time-integrated x-ray intensity had a value of approximately 50 μGy at 1.0 m from the x-ray source with a charging voltage of 80 kV. Angiography was performed using a film-less computed radiography system and gadolinium-based contrast media. In angiography of non-living animals, we observed fine blood vessels of approximately 100 μm with high contrasts.
A microfocus x-ray tube is useful in order to perform magnification digital radiography including phase-contrast effect. The 100-μm-focus x-ray generator consists of a main controller for regulating the tube voltage and current and a tube unit with a high-voltage circuit and a fixed anode x-ray tube. The maximum tube voltage, current, and electric power were 105 kV, 0.5 mA, and 50 W, respectively. Using a 3-mm-thick aluminum filter, the x-ray intensity was 26.0 μGy/s at 1.0 m from the source with a tube voltage of 60 kV and a current of 0.50 mA. Because the peak photon energy was approximately 38 keV using the filter with a tube voltage of 60 kV, the bremsstrahlung x-rays were absorbed effectively by iodine-based contrast media with an iodine K-edge of 33.2 keV. Magnification angiography including phase-contrast effect was performed by three-time magnification imaging with a computed radiography system using iodine-based microspheres 15 μm in diameter. In angiography of non-living animals, we observed fine blood vessels of approximately 100 μm with high contrasts.
The cerium-target x-ray tube is useful for performing cone beam K-edge angiography, because K-series characteristic x-rays from the cerium target are absorbed effectively by iodine-based contrast media. The x-ray generator consists of a main controller and a unit with a high-voltage circuit and a fixed anode x-ray tube. 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 are 65 kV and 0.4 mA, respectively, and the focal-spot sizes are 1.3×0.9 mm. Cerium K-series characteristic x-rays are left, using a 3.0-mm-thick aluminum filter, and the x-ray intensity is 19.9 µGy/s at 1.0 m from the source with a tube voltage of 60 kV and a current of 0.40 mA. Angiography is performed with a computed radiography system using iodine-based microspheres 15 µm in diameter. In angiography of nonliving animals, we observe fine blood vessels of approximately 100 µm with high contrasts.
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 K 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 are 90 kV and 0.8 kA, respectively. The x-ray pulse widths are approximately 80 ns, and the instantaneous number of generator-produced K photons is approximately 4×107photons/cm2 per pulse at 0.3 m from the source 3.0 mm in diameter.
The tantalum plasma flash x-ray generator is useful in order to perform high-speed K-edge angiography using cone beams because Kα rays from the tantalum target are absorbed effectively by gadolinium-based contrast media. 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. When the charging voltage was increased, the K-series characteristic x-ray intensities of tantalum increased. The K lines were clean and intense, and hardly any bremsstrahlung rays were detected. The x-ray pulse widths were approximately 100 ns, and the time-integrated x-ray intensity had a value of approximately 300 μGy at 1.0 m from the x-ray source with a charging voltage of 80 kV. Angiography was performed using a film-less computed radiography (CR) system and gadolinium-based contrast media. In angiography of non-living animals, we observed fine blood vessels of approximately 100 μm with high contrasts.
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 K rays are produced using a 10-µm-thick nickel filter. At a charging voltage of 50 kV, the maximum 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 K intensities substantially increase. The K 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 µC/kg at 1.0 m from the x-ray source with a charging voltage of 50 kV.
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.
Energy-selective high-speed radiography utilizing a kilohertz-range stroboscopic x-ray generator and its application to high-speed angiography are described. This generator consists of the following major components: a main controller, a condenser unit with a Cockcroft-Walton circuit, and an x-ray tube unit in conjunction with a grid controller. The main condenser of about 500 nF in the unit is charged up to 100 kV by the circuit, and the electric charges in the condenser are discharged to the triode by the grid control circuit. Although the tube voltage decreased during the discharging for generating x rays, the maximum value was equal to the initial charging voltage of the main condenser. The maximum tube current and the repetition rate were approximately 0.5 A and 32 kHz, respectively. The x-ray pulse width ranged from 0.01 to 1.0 ms, and the maximum shot number had a value of 32. At a charging voltage of 80 kV and a width of 1.0 ms, the x-ray intensities obtained without filtering, using an aluminum filter, and using a barium sulfate filter were 14.8, 5.48 and 5.05 μGy per pulse, respectively, at 1.0 m, and the dimensions of the focal spot had values of 3.5×3.5 mm. Angiography was performed using both the aluminum and the barium sulfate filters at a charging voltage of 60 kV.
High-voltage condensers in a polarity-inversion two-stage Marx surge generator are charged from -50 to -70 kV using a power supply, and the electric charges in the condensers are discharged to an x-ray tube after closing the gap switches in the surge generator using 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 copper Kα lines are produced using a 10-μm-thick nickel 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. The peak tube voltage increased with increasing charging voltage. At a charging voltage of -70 kV, the peak tube voltage and current were 140 kV and 0.8 kA, respectively. The pulse widths were approximately 30 ns, and the maximum dimension of the x-ray source was 3.0 mm in diameter. The number of generator-produced Kα photons was approximately 2.5x106 photons/cm2 at 0.5 m per pulse.
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 molybdenum 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 16 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. The x-ray pulse widths were approximately 600 ns, and the time-integrated x-ray intensity had a value of approximately 65 μC/kg at 1.0 m from the x-ray source with a charging voltage of 50 kV.
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.
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.
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.
The cerium target plasma flash x-ray generator is useful in order 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 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 cerium 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 10 μC/kg at 1.0 m from the x-ray source with a charging voltage of 80 kV. In the angiography, we employed a film-less computed radiography (CR) system and iodine-based microspheres.
The cerium-target x-ray tube is useful in order to perform cone beam K-edge angiography 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 and a unit with a high-voltage circuit and a fixed anode x-ray tube. 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 1.3×0.9 mm. Cerium K-series characteristic x rays were left using a 3.0 mm-thick aluminum filter, and the x-ray intensity was 0.59 μC/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 15 μm in diameter. In angiography of non-living animals, we observed fine blood vessels of approximately 100 μm with high contrasts.
The development of an extremely soft x-ray generator with a tungsten-target tube and its applications to radiography and disinfection are described. This generator consists of a high-voltage power supply, a filament power supply, and an x-ray tube. Negative high voltages are applied to the cathode electrode in the x-ray tube, and the tube voltage and current are regulated by the input of a transformer and the filament voltage, respectively. The x-ray tube is a glass-enclosed double-focus diode with a tungsten target and a 0.2 mm-thick beryllium window. The maximum tube voltage and electric power were 60 kV and 400 W, respectively. The focal-spot sizes were 4×4 (large) and 1×1 mm (small), respectively. Extremely soft radiography was performed with a computed radiography system, and we observed fine blood vessels of about 100 μm with high contrasts. Using this generator, we performed the disinfection achieved with extremely soft x rays.
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