| Co-Investigator(Kenkyū-buntansha) |
MARUOKA Shin Tohoku University, School of Medicine, Professor, 医学部, 教授 (90173947)
ZUGUCHI Masayoshi Tohoku University, School of Medicine, Professor, 医学部, 教授 (20172075)
OHISHI Mikio Tohoku University, School of Medicine, Professor, 医学部, 教授 (20004921)
HONMA Noriyasu Tohoku University, School of Medicine, Associate Professor, 医学部, 助教授 (30282023)
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| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2003: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2002: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2001: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
The, x-ray tube used in the conventional medical x-ray generator is a hot cathode diode using thermionic emission, while we have developed a flash x-ray generator with a cold cathode diode driven by field emission. The flash x rays are produced by the high energy vacuum discharge, and the generator consists of a DC high-voltage power supply, a high voltage condenser, a cold cathode x-ray tube, an air gap switch, a trigger pulse generator, and a vacuum pump. The x-ray tube is composed of an anode (target), cathode, and trigger electrodes. In this field emission tube, the anode and cathode electrodes can be changed, and the space between the anode and cathode electrodes is controlled in order to obtain optimum x-ray intensity. In addition, the space between the cathode and trigger electrodes should be decreased as much as possible to decrease the trigger voltage. In the tube, conical anode (1200) and cathode (500) electrodes are employed, and their elements are tungsten and carbon (graphite), respectively. The vacuum pump evacuates air from the tube with a pressure of 6.65 x 10^<-3> Pa, and the pulse width and the maximum tube current were approximately 300 ns and 40 kA, respectively, with a charging voltage of 80 kV. In order to measure the dimensions of the focal spot, we employed a pinhole camera, and the dimension varied with changes in the electrode angles and the spaces between electrodes. In high speed radiography, we obtained stop motion images of various objects including plastic bullets and water flows. In summary, the flash x-ray generator developed in the research is useful to perform high speed radiographies of children or disabled persons, because the generator produces extremely short x-ray pulses.
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