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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.
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