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Volume 8 (1991)
- Issue 3 Pages 73-
- Issue 2 Pages 35-
- Issue 1 Pages 1-
Volume 8, Issue 1
Displaying 1-4 of 4 articles from this issue
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Toru YANAGISAWA1991 Volume 8 Issue 1 Pages 1-4
Published: 1991
Released on J-STAGE: August 27, 2012
JOURNAL FREE ACCESSDownload PDF (3660K) -
Eiichi SATO, Hiroshi ISOBE, Shingo KIMURA, Arimitsu SHIKODA, Kei TAKAH ...1991 Volume 8 Issue 1 Pages 7-17
Published: 1991
Released on J-STAGE: August 27, 2012
JOURNAL FREE ACCESSThe diagnostic soft flash x-ray generators and their applications to high-speed radiography are described. Each flash x-ray generator consisted of the following essential components: a high-voltage power supply, a high-voltage pulser, a high-speed impulse switching system, and an x-ray tube. The flash x-ray generators may be used for peak tube voltages of 40 to 150kV and the peak currents of less than 5OkA. The exposure times were less than 50μs, and the x-ray qualities were primarily determined by the peak voltages of the x-ray tube. The repetitive rate was determined by the capacity of the main discharge condenser, the charged voltage, and the current capacity of the high-voltage power supply; its value was less than 50Hz. But, when a flash x-ray generator with an energy storage condenser was employed, the repetitive rate can be increased up to 100Hz. Various kinds of high-speed radiography, e. g., the delayed radiography and the stroboscopic radiography, could be performed by controlling the following radiographic conditions: the x-ray intensity, the x-ray quality, the exposure time, the delay time, and the repetitive rate.View full abstractDownload PDF (6190K) -
Katsumi NIWA, Shinya HIROTA, Kouji YAMAMOTO, Nobuya OKAWA1991 Volume 8 Issue 1 Pages 18-22
Published: 1991
Released on J-STAGE: August 27, 2012
JOURNAL FREE ACCESSThe purpose of this study was to clarify the influence of the tube voltage on the graininess of nonscreen x-ray film. The tube voltage was set at 10 kV intervals from 40kv to 90kV. Total filtration used was 27mm as the aluminium equivalent. Ag-particle size was determined microscopically by easuring the length on the x-axis of the particle image incorporated in the memory one-dimensionally. In order to compare with the film graininess only, the particle size when x-ray film was exposed to visible ray from a fluorescent lamp was also determined. ULTRA speed film manufactured by Kodak Co. was used in this experiment.
Results obtained were as follows: Among 104 particle sizes thus determined, there were about 9 particles of 10μm in size from visible ray. On the other hand, approximately 30 particles were confirmed with 90kV,27mm Al filtration. When these particles were observed microscopically, it was revealed that the greater part of Ag-particles were identical irrespective of the tube voltage. However, a large mass of Ag-particle was found to be formed when the tube voltage was high.
In the case of nonscreen x-ray film, the film was directly sensitized with x-ray. It was also estimated that the mass formation of Ag-particles may be attributable to the scattered ray (photoelectron)from first interacted Ag-particle.View full abstractDownload PDF (1693K) -
Seihaku HIGUCHI1991 Volume 8 Issue 1 Pages 23-28
Published: 1991
Released on J-STAGE: August 27, 2012
JOURNAL FREE ACCESSAn arithmetic coding is well known as a powerful and an interesting data compression techniques from information theoretic viewpoints. For the practical use, some fundamental problems such as an error propagation and an application to multi-valued images instead of mono-chromatic images have been remained unsolved. In order to apply this technique for the multi-valued images, a simplified and a feasible processing method have to be developed.
In this paper, in order to adopt the specified statistical properties of the images, Markov source model was formulated to express the correlation value between the digits in binary expression of brightness. That is, statistical properties of lower order digits in the binary expression are modified with dependent on both the brightness of higher order digits and the brightness of neighboring pixels. Simulation studies were carried out for SIDBA images and X-ray image to show the effectiveness of our approach.View full abstractDownload PDF (1961K)
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